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Planet Earth/4g. What are Clouds?

Clouds
On a summer day, clouds might float overhead, their passage only noticed if you take the time to observe them. Clouds come in all shapes and sizes, but their unique physical properties can be classified, and sky-gazers have come up with names based on the characteristics of clouds on Earth. The names are composed of Latin words, Nimbo- for rain, Alto- for high, Cumulus- for heap or mound, Strato- for flat, and Cirrus- for curl or wisp.

Cumulus clouds
These clouds are the classic white puffy, cotton-candy like clouds you observe on a late summer afternoon. The tops of the cloud are often rounded, as the cloud grows upward, with a flat base that may be a few hundred meters above the ground. In the late afternoon, cumulus clouds can grow larger forming a cumulus congestus, or towering cumulus. If enough moisture develops in a cumulus cloud, and it grows even bigger, and grayer, it can turn into a cumulonimbus cloud.

Cumulonimbus clouds
These clouds are towering giant clouds associated with thunderstorms. Climbing upward into the atmosphere more than 12 kilometers, these clouds can release huge amounts of rain, snow, hail, and are associated with lightning and thunder and even tornadoes. Near the top they will sometimes form anvil heads. Near the base they will form a grayish or bluish color, because of the super saturation of water vapor. Often rain or snow will fall beneath a cumulonimbus cloud. Evening summer thunderstorms are often a result of cumulonimbus clouds.

Stratocumulus clouds
These clouds resemble cumulus clouds that are flattened, and usually manifest in the sky in low groups or lines of clouds. These clouds lack much height, often due to stable air above which prevents upward growth. Rarely do these types of clouds produce rain or snow, and they tend to precede warming weather. Stratocumulus clouds often form lines or lenticular patterns in the sky.

Altocumulus clouds
These clouds resemble individual scattered globular patches in the sky, found higher up in the sky. These high patchy clouds do not often produce rain, but have been known to evolve into cumulonimbus clouds. Altocumulus clouds often speckle the sky, and can vary in thickness, with some being thin wispy clouds, while others thicker and more bulbous.

Cirrocumulus clouds
These clouds are high altitude clouds, that are found near the top of the troposphere, between 10 and 14 kilometers above the surface of the Earth. These clouds often contain more ice crystals than liquid water, and can produce snowflakes on cold days. They can form from the breakup of large clouds, like cumulonimbus clouds after a storm.

Cirrus clouds
These clouds form high in the troposphere, around 14 to 16 kilometers, and produce thin wispy clouds high in the sky. Cirrus clouds are composed of ice crystals that originate from the freezing of supercooled water droplets. They often appear transparent, like wedding veils high in the sky.

Stratus clouds
These clouds are very low flat and featureless clouds that roll across the sky during the beginning of a cold front. Often stratus clouds are gray and dark in color, but sometimes can be white. Foggy and low to the ground, these clouds will hug mountains and hills, and represent an extended period of colder weather with rain and snow. Most fog is classified as stratus clouds, which can form in the cooler morning hours or after rainstorms.

Nimbostratus clouds
These clouds are similar to stratus clouds, but are much thicker and darker, and are associated with cold fronts. Nimbostratus clouds are observed during significant rain and snow accumulations that follow a cold front, and often found in the sky on cold rainy or snowy days. These clouds often blanket the entire sky on cold rainy days, but only extend upward 2 to 4 kilometers. If the sky is completely covered in clouds, on a cloudy day, it is often a result of nimbostratus clouds.

Altostratus clouds
These clouds are similar to altocumulus clouds, but are thicker, and spread out over the sky at heights between 6 and 10 kilometers. They are not as wispy or transparent, and can cover much of the sky with clouds. Since they are higher in the sky, they tend not to be associated with rain or snow, but hang over the landscape as featureless clouds.

Unusual or Rare Cloud Formations
A number of strange cloud formations have been given names and described. The most iconic is likely the Lenticularis clouds, which resemble gigantic circular UFOs. They are a type of altocumulus cloud which are carved by wind into oval-like shapes high in the sky. Virga clouds are thin wispy clouds that drape down from rain clouds. Virga are caused by precipitation that falls from the underside of a cloud, often the moisture evaporates before it reaches the ground, although it can cause a light shower of rain or snow directly below its veil. Mackerel Sky is a sailor term for a sky filled with rows of small cirrocumulus or altocumulus clouds displaying a speckled pattern of clouds that look slightly like the scales of mackerel fish, caused by high altitude atmospheric winds. Mackerel Skies are often used by sailors to forecast rain, since they occur as barometric pressures fall, indicating a low-pressure system is developing. Nacreous clouds are only found in Arctic regions, and are high iridescent-colored clouds that form near the top of the Troposphere when the atmosphere is extremely cold. They are most often observed in cold and dry polar regions, and are formed from ice crystals high in the atmosphere. They are often referred to as polar stratospheric clouds, and are sought after by cloud watchers. Noctilucent clouds are scientifically interesting rare clouds that are found within the Mesosphere, at very high altitudes above Earth. They are often observed following a major volcanic eruption, and are thought to be caused by volcanic dust and water vapor that is injected into the high Mesosphere where they form wispy thin clouds best seen near sunset or sunrise. They have been observed after rocket launches, when particulates and water vapor are carried high into the atmosphere from the rockets as they combusted fuel during lift off. Mammatus clouds are pillow-like clouds that can form below cumulonimbus clouds, the term comes from the Latin word for breast or utter, mamma. Kelvin–Helmholtz clouds are caused by velocity differences between two layers of the atmosphere, which results in wave-like clouds that resemble crashing ocean waves. They are named after English physicist Lord Kelvin and German physicist Hermann von Helmholtz who both described the physics of these wave formations in the 1860s and 1870s. Arcus clouds are a rare kind of storm clouds that rolls across the sky. They are associated with cold fronts and thunderstorms, which cause the clouds to appear to roll over the landscape. They are known by other names, including Roll clouds, Shelf clouds, or Volutus clouds. Arcus clouds are related to the phenomena of rolling giant dust clouds called haboob, which comes from the Arabic term for blasting or drifting. Haboobs form where strong gushes of wind blow across an arid landscape lifting dust and particles into the air. They proceed thunderstorms and advancing lower pressure fronts, which bring strong winds. Haboobs can cause respiratory problems since these airborne dust particles can be breathed in by people trapped in these storms. Sun dogs, or parhelion are strange and rare atmospheric events that cause the sun to appear to have two bright spots that flank the sun on either side. These sun dogs are caused by ice crystals within cirrus or cirrostratus clouds reflecting a large halo around the sun around 22 degrees to either side. These Sun dogs can be particularly bright when the sky contains thin cirrus clouds which reflect the sunlight passing through them.

How clouds form, moisture in the atmosphere
Clouds are intricately intertwined with the phases of water in the atmosphere; liquid water, water vapor, and ice/snow. Changes in the temperature and pressure near the surface of the Earth, in the Troposphere, can result in the formation of any of these phases through the process of evaporation (liquid → gas), condensation (gas → liquid), and precipitation (gas → liquid or solid). Liquid water is converted to a gas through evaporation, which occurs when excited molecules escape from a heated source of water and move into the air as water vapor. When the number of water molecules evaporating matches the number of water molecules condensing the air is considered saturated in relationship to water vapor. Saturated air is air that is at the maximum level of its possible concentration of water vapor at a given temperature and pressure. When air becomes oversaturated with water vapor, water will condense into liquid and can be seen as visible clouds in the sky. Imagine a jet engine on an airplane flying at a set altitude, with no change in air pressure. Air passing through the jet engine will be heated by the engines resulting in an undersaturation of water vapor in the passing air through the engine’s exhaust, as the heated air now has the capacity to contain more molecules of water. The surrounding water molecules will rush into this undersaturated air, but as the air begins to cool several seconds after the jet engine and its heat has passed, the air will become oversaturated in respect to water vapor, and the water vapor will condense into a line of clouds in the sky. These contrails etch a path across the sky, leading to manmade clouds visible from Earth’s surface. If the air is already oversaturated in respect to water vapor, and the jet engine passes through a cloud of condensing water, the passing jet engine can heat the air, increasing the saturation of water vapor, and cause the cloud to disappear. These events can form fallstreak holes or trails through natural forming clouds.

Clouds form anytime the temperature or pressure of the air moves from saturation to oversaturation, with oversaturation of water vapor resulting in the condensation of liquid water and the formation of clouds in the sky.

Dalton's law
On the morning of July 26, 1844, when the elderly John Dalton recorded his meteorological observations for the day, he wrote shakily 60 for the temperature inside his apartment, 71 for the temperature outside, 30.18 for the barometer reading, SW 1 for a gentle southwest wind direction, and the observation, Little Rain. 60, 71, 30.18 SW 1, Little Rain. It was the last entry in a series of over 200,000 weather recordings that John Dalton had first begun in 1787, when he was only 21 years old, although with more earnest in 1794. Now, an old man, his entire life was recorded by the weather observed each day of his long life, a total of 57 years of weather observations. When he died the next day of a stroke, thousands of people across Manchester, England, came to his funeral. He was famous, not for his diligent record he kept of the weather or his small shabby apartment, and his stoic life as a life-long bachelor, John Dalton was well respected because of his keen understanding of the relationship between gas and pressure, and the discovery that atoms or molecules of gas contain masses of differing sizes. Today, atmospheric scientists know him for developing Dalton's law, which states that total pressure exerted by a mixture of gasses is equal to the sum of the partial pressures of each individual gas within the mixture. For example, in air at sea level, under 101.3 kPa of pressure, Nitrogen will exert 78.1 kPa of pressure, Oxygen 20.9 kPa of pressure, Argon 0.97 kPa, water somewhere around 1.28 kPa, and carbon dioxide 0.05 kPa, in direct relationship to the percentage of each gas within the mixture of gasses found within normal air at sea level.

This means that if water vapor is added to a gas, the total pressure of the gas will increase. Saturation pressure of water vapor is the maximum water vapor capacity at any given temperature for a mixture of gasses. If the added water vapor is more than the saturation pressure of water vapor, then the gas will begin to condense, appearing as liquid water, with molecules moving from the gas to liquid phase. The vapor pressure cannot be higher than this maximum capacity, so any gas that is higher than the saturation pressure, will result in the condensation of water. However, air can be under-saturated. Relative humidity is the ratio of the water vapor pressure in air, with respect to the saturation water vapor pressure, or maximum capacity of the air to hold water vapor.

If relative humidity is 100%, then condensation of water vapor will occur. However, if the relative humidity is only 15%, then the air is undersaturated in respect to water vapor. The saturation pressure of water vapor is dependent on the temperature, the higher the temperature the more water vapor the air can hold, for example a recording of atmospheric gas at 40 degrees Celsius with 95% relative humidity, will have a considerable larger total amount of water vapor, than atmospheric gas at 0 degrees Celsius with 95% relative humidity. This relationship results in sticky, muggy, hot weather, in places with an abundance of liquid water, while cold regions will be drier. Hot places, like arid deserts that lack a source of liquid water, such as deserts in the interior of continents, will often be highly undersaturated in respect to water vapor, with very low humidity, such as 5 to 25% common. Note that when relative humidity reaches 100% condensation occurs, and clouds, precipitation, or fog will form. Note that when temperatures drop, the saturation water vapor pressure will change, resulting in a rise in relative humidity without changing the amount of water vapor in the air. If this cooling air reaches a relative humidity of 100%, condensation will occur and clouds will form, this is referred to as the dew point.

Adiabatic Lapse Rate
The best way to think about the Adiabatic Lapse rate is to think of it as a track, forcing air or any material under different pressures and temperatures to follow a very specific passage with altitude. Adiabatic Lapse is a result of how temperature and pressure are related. You may have observed how a canister of compressed air will cool, even growing ice crystals on its surface when gas inside the canister is released. While increasing the pressure inside a tire, the tire will grow hot from the increase in air pressure. When air expands it cools, when air is compressed it heats up. Imagine hot air rising, as it rises the air expands, resulting in the air cooling down as it rises. Imagine cold air sinking, as it is compressed with more pressure, the air will warm. This process is an adiabatic process, which means that air moving between elevations will follow a narrow path along temperature and altitude. This Adiabatic Lapse is 10 degrees Celsius colder every 1 kilometer of altitude (10°C/km). Above an area of Earth’s surface that is 30 degrees Celsius, the air 3 kilometers above will be 0 degrees Celsius. If that air mass moves closer to the Earth, dropping to an altitude of 2 kilometers above Earth, the temperature of the air mass will increase by 20 degrees Celsius. It is important to note that the adiabatic lapse rate is a physical condition of the motion and expansion/contraction of air under different pressures, and not caused by the temperature profile of the Earth. If there was no temperature differences between the layers of the atmosphere, any air that rises and expands would cool, and any air that sinks and contracts would warm.

This Adiabatic Lapse is called the dry adiabatic lapse rate because we assume the air is dry, and below the Saturation pressure of water vapor. However, if the air is cooling as it rises, the air will reach a point where it will be unable to hold as much water vapor and eventually, with enough altitude and cooling, the saturation pressure of water vapor will be reached, and condensation will occur, at which point clouds will form. Clouds form at high altitudes because the air mass cools below the saturation pressure of water vapor for the concentration of water vapor within the rising air mass. If these air masses are moving upward, they will often cross this point forming clouds in the sky. If air moves swiftly higher, and carry a large amount of water vapor, the condensation of this water vapor with height will result in the possibility of significant precipitation of rain or snow. The moist adiabatic lapse rate is slightly less with an average of 6 degrees Celsius colder for every 1 kilometer of altitude (6°C/km). The Adiabatic Lapse Rate is the reason that clouds rarely form near the surface of the Earth, but often higher in the sky. Understanding the rising and falling of air, and changes in pressures observed from the surface of the Earth using a barometer is necessary for knowledgeable insight into the nature of wind on Earth and understand weather forecasting.

Clouds and Climate Change
As global temperatures in the troposphere have been rising over the last century with rising carbon dioxide and other greenhouse gasses, scientists have hypothesized that the world will become cloudier over time. Any addition of global cloud cover would increase the albedo of the Earth resulting in more sunlight reflected back into space. This would act like a negative feedback and cool the planet. Satellites launched into space, such as instruments aboard NASA’s Terra and Aqua satellites, as well as older satellites like NOAA’s High-Resolution Infrared Radiometer Sounder (HIRS) have been measuring the Earth’s cloud cover. Results since 1978 show that Earth’s cloud cover has not trended upward nor downward, but appears to vary yearly within a narrow range. Slight changes observed seem to reflect enhanced atmospheric circulation, but no net increase in cloud cover since observations begun in the late 1970s.

title: Planet Earth/4g. What are Clouds?


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Badminton/Comparisons with other racquet sports

In some ways, badminton is way better than tennis, as it requires more agility (arguably), stamina, and accuracy.

Tennis, on the other hand, is a faster game, and requires more strength.

See the following table:

 * |Tennis     |Badminton |

 * Strength|👍         |👎        |

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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A-level Mathematics/CIE/Pure Mathematics 2/Integration

Power Rule
The power rule for differentiation states that:

$$\dfrac{d}{dx} x^n = nx^{n-1}$$

The reverse of this is $$\int nx^{n-1} dx = x^n + c$$, which can be written as $$\int x^n dx = \frac{x^{n+1}}{n+1} + c$$

This is the power rule for integration.

Exponentials & Logarithms
Regarding the derivatives of exponentials and logarithms, we know that:

 * $$\dfrac{d}{dx} e^x = e^x$$
 * $$\dfrac{d}{dx} \ln x = \frac{1}{x}$$

Reversing these, we get:

 * $$\int e^x = e^x + c$$
 * $$\int \frac{1}{x} = \ln |x|$$

The natural logarithm takes a modulus input so that it can handle negative numbers.

Note that similar rules apply to any linear expressions that may be composed with these functions:

 * $$\int e^{ax+b} = \frac{1}{a}e^{ax+b} + c$$
 * $$\int \frac{1}{ax+b} = \frac{1}{a}\ln|ax+b|$$

Trigonometric Functions
The derivatives of the trigonometric functions are:

 * $$\dfrac{d}{dx} \sin x = \cos x$$
 * $$\dfrac{d}{dx} \cos x = -\sin x$$
 * $$\dfrac{d}{dx} \tan x = \sec^2 x$$
 * $$\dfrac{d}{dx} \tan^{-1} x = \frac{1}{1+x^2}$$

Thus, the corresponding integrals are:

 * $$\int \cos x = \sin x + c$$
 * $$\int \sin x = -\cos x + c$$
 * $$\int \sec^2 x = \tan x + c$$
 * $$\int \frac{1}{1+x^2} = \tan^{-1} x + c$$

As with exponentials and logarithms, this applies to linear expressions that are composed with trigonometric functions:

 * $$\int \cos (ax+b) = \frac{1}{a}\sin(ax+b) + c$$
 * $$\int \sin (ax+b) = -\frac{1}{a}\cos(ax+b) + c$$
 * $$\int \sec^2 (ax+b) = \frac{1}{a}\tan(ax+b) + c$$
 * $$\int \frac{1}{1+(ax+b)^2} = \frac{1}{a}\tan^{-1}(ax+b) + c$$

Using Trigonometry when Integrating
Sometimes, it is useful to use trigonometric identities when finding the integral of an expression.

e.g. Find the integral $$\int 4\cos^2 x dx$$.

$$\begin{align} \cos 2x &= 2\cos^2 x - 1 \quad\text{Double Angle Identity} \\ \cos^2 x &= \frac{\cos 2x - 1}{2} \\ \int 4\cos^2 x dx &= \int 4\frac{\cos 2x - 1}{2} dx \\ &= \int \cos 2x - 1 dx \\ &= \frac{1}{2}\sin 2x - x + c \end{align}$$

Trapezium Rule

The trapezium rule states that the area under a curve can be approximated by finding the sum of the areas of trapeziums. The area of a trapezium is given by $$A = \frac{B+b}{2}h$$ Where $$B$$ is the length of the longer side, $$b$$ is the length of the shorter side, and $$h$$ is the length of the perpendicular distance between the sides.

In the context of the trapezium rule, each trapezium's perpendicular distance $$h$$ is a constant $$\Delta x$$: the width of each trapezium. The lengths of the sides are given by points on a curve. Thus, for a curve $$f(x)$$ approximated using trapeziums, each trapezium has an area $$A_i = \frac{f(x_i)+f(x_{i+1})}{2}\Delta x$$.

The area under the curve between the bounds $$a$$ and $$b$$ is the sum of the trapeziums' areas: $$A = \sum_{x=a}^b \frac{f(x)+f(x+\Delta x)}{2}\Delta x$$.

Because $$\Delta x$$ is constant, the expression for the area can be written $$A = \frac{f(a) + 2f(a+\Delta x) + 2f(a+2\Delta x) + \dots + 2f(b - \Delta x) + (b)}{2} \Delta x$$, which can be simplified to $$A = \left(\frac{f(a) + f(b)}{2} + f(a+\Delta x) + f(a+2\Delta x) + \dots + f(b - \Delta x)\right)\Delta x$$

Thus, the trapezium rule states:

$$\int_a^b f(x) dx \approx \left(\frac{f(a) + f(b)}{2} + f(a+\Delta x) + f(a+2\Delta x) + \dots + f(b - \Delta x)\right)\Delta x$$

Trapezium Rule Worked Example
Q. Use the trapezium rule with 4 intervals to estimate the value of $\int_{0}^{4} 2\sqrt{4x-x^{2}}~dx$, giving your answer correct to 2 decimal places.

A.

$a=0$, $b=4$ , and $h=1$

$$\int_{0}^{4}2\sqrt{4x-x^2}~dx\approx\frac{h}{2}\left[y_0+y_4+2\left(y_1+y_2+y_{3}\right)\right] $$

$$\approx\frac{1}{2}[0+0+2(2\sqrt{3}+4+2\sqrt{3})] $$

$$\approx4\sqrt{3}+4 $$

$$\approx10.93 $$ (to 2 decimal places)


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Wikibooks:Reading room/Proposals/2020/February

Maintenance
I have long felt the usefulness of page Maintenance is limited by the fact that, although it lists lots of kinds of tasks one might undertake, it doesn't actively tell you which of those sorts of tasks actually has a queue of items waiting to be taken care of; to find that out you'd have to check them all one-at-a-time. A different approach is used at en.wn, where a template called (for partly historical reasons) votings/sorted lists all the task-queues that are non-empty, and how long each queue is. (Actually it's more sophisticated than that: the queues are sorted into three sets listed on separate lines according to theme (news production, community discussions, admin tasks); most of the empty queues are also listed but moved to the end of the list and greyed out; and some of the queues when nonempty are shaded in various colors to draw attention to them.)

I'm thinking we might enhance the usefulness of Maintenance by adding some such dynamic list up at/near the top. --Pi zero (discuss • contribs) 15:55, 4 February 2020 (UTC)

 * Hi Pi zero well yes that sounds like a definite improvement. I'd be interested to see what you could come up with. -- Jules (Mrjulesd) 12:31, 5 February 2020 (UTC)

 * I've been thinking about how this might be done. Some queue sizes can be determined using magic word , but others have no associated category.  Such as Special:Uncategorizedpages.  I was hoping to parse its contents using evalx, but the wiki platform does not allow these special pages to be transcluded. --Pi zero (discuss • contribs) 13:23, 5 February 2020 (UTC)


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Selected Essays/Climate Change

Climate Change refers to a statistically significant variation in either the general state of the climate or in its variability, persisting for an extended period, typically decades or longer.

Change in climate may be due to natural internal processes or external factors, due to persistent changes in the composition of the atmosphere, or in land use brought by humans. short-term fluctuations like El-Nino, represent variation in climate for short temporary periods. On a longer time scale, changes in ocean heat circulation pattern may result in a stronger impact on climate. Variations in Earth's orbit lead to differences in the distribution of sunlight reaching the Earth in different seasons and at different places on Earth. The solar intensity is also known to affect global climate.

Volcanic eruptions are also considered to be significant in affecting Earth's climate, especially those which emit large quantities of So2 into the stratosphere. This is due to the optical properties of So2 and sulphate aerosols. They absorb or scatter solar radiation, creating a haze of sulphuric acid. Other than volcanoes, the movement of tectonic plates affects the global and local pattern of climate. Anthropogenic factors relate to human activities which include burning of fossil fuels, ozone depleting causes, and deforestation. Due to industrialization and urbanisation, presently, the global atmospheric concentration of carbon-dioxide has increased to 393,69 parts per million (ppm). These could lead to impact on freshwater availability, oceanic acidification, food production, flooding of coastal areas and increased number of water borne diseases associated with extreme weather events.

Glaciers are one of the most sensitive indicators of climate change. Their size is determined by the input of snow and their melting output. Due to rising global temperatures, their size shrinks, leading to escalation of sea levels. The ice on Arctic Ocean is also melting rapidly, which is another proof of climate change. Due to climate change, the distribution and density of vegetation may also be affected. The increase in temperature will lead to early onset of flowering and fruiting, which will affect the life cycles of animals dependent on them. One example is the destruction of rainforests of Europe and America, 300 million years ago. These forests fragmented into isolated ‘islands’ leading to the extinction of many plant and animal species.

India is facing the challenge of sustaining its rapid economic growth while dealing with the global threat of climate change. This threat emanates from accumulated greenhouse gas emissions, generated through long-term industrial growth and high consumption lifestyles. Presently, India is among the top 10 emitters of Greenhouse Gases in the world. However, it is in India’s interest to ensure that the world moves towards a low carbon future. With changes in key climate variables, namely temperature, precipitation and humidity, crucial sectors like agriculture and rural development are likely to be affected in a major way. As a developing country, India is closely tied to natural resources and agriculture, and water and forestry are climate-sensitive.

To combat climate change, India’s National Action Plan for Climate Change (NAPCC) aims to achieve national growth objectives, along with enhancing ecological sustainability that leads to further mitigation of greenhouse gas emissions. NAPCC endeavours to deploy appropriate technologies, for both adaptation and mitigation of greenhouse gases and to promote sustainable development.

NAPCC also plans to extend international cooperation for research, development, sharing and transfer of technologies enabled by additional funding. India is a member of the United Nations Framework convention and intends to cooperate with the same on Climate Change. The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty produced at the United Nations conference on Environment and Development (UNCED), and is greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

The 2011 Annual Conference of the Parties was hosted by Durban, South Africa, from 28 November to 9 December, 2011. In 2012, Earth Summit took place in Rio de Janeiro to secure renewed political commitment to sustainable development; to assess progress towards internationally agreed goals on sustainable development and to address new and emerging challenges. The Summit focused on two specific themes – a green economy in the context of poverty eradication and an institutional framework for sustainable development.

We, as individuals also can contribute towards lessening our impact on the climate by modifying our transportation modes, energy consumption, eating habits and waste utilization. Short distances can be covered by walking or cycling or even car-pooling. In place of the conventional light bulbs, LEDs can be used. Electrical appliances should be switched off when not in use.

Our tiny carbon footprint also affects the big picture of climate change. Even though, we might feel that our lifestyle is a small factor, but the choices that we make in our day-to-day life can play a major role in slowing down climate change. Let us all strive for a ‘Cleaner and Greener’ Earth.

title: Selected Essays/Climate Change


text: Category:Book:Selected Essays

title: Category:Book:Selected Essays


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Linux Basics/The structure of Linux

 * Basically it's CLI
 * like DOS and Windows's command prompt
 * There are graphical user interfaces too (GUI)

Filesystem

 * There are no letters at disks, like in DOS/Windows -> Everything is under /
 * It mounts (connects) the external storages
 * Nowadays Windows is also capable of it
 * The /etc/fstab file contains the automatical mount point of partitions and settings associated with them.
 * or  commands, latter one lists the partitions.
 * Under /mnt we can find the mounted mediums (but that's not true mostly because in modern partitions the automatically mounted mediums like flash drives usually get mounted to /media, but that's true that /mnt is created to mount partitions there)

FAT-table contains entries for every cluster on a continuous area of the medium. Every entry contains the next cluster's number in a file or the EOF (end of file), unused disk space and the specially reserved space of the disk. It only can do soft-link.

EXT filesystem: It uses inode(Index node) table. In inode there are the files' description and the place of the data blocks, without filename. There is only one inode for each file. Files with bigger size may contain multiple catalog-entries, which contains the filename. Inode contains the name, description, creation date, permissions, owner(UID), group(GID), and how many links are attached to it. (so it can do much more than FAT) It can do soft-link and hard-link, which is one of the biggest advantage of EXT file system to FAT.

 * Soft-link: shortcut, if the original gets deleted, then it deletes itself, or it says error that it doesn't find the executable.
 * Hard-link: A copy of the file, but if we change the original one, then the content of the copy changes, but the file will only disappear eventually, if all the copies are deleted.

Properties of filesystem

 * It attaches permissions separately to every file
 * It limits permission to the owner or groups
 * Read, write, execute permissions

File managers

 * mc (Midnight Commander) - CLI - it's based on Norton Commander
 * Gnome Commander - GUI
 * and the graphical file managers that you get with the Desktop Environment you use: thunar, nautilus, rox-filer, dolphin, pcmanfm, stb. (https://www.tecmint.com/top-best-lightweight-linux-file-managers/)
 * File managing: operations with files

Kernel
Kernel = system core, the "soul" of the OS

Tasks of it: handling peripherals, handling filesystem, implementing directory structure, taking control of processor

Types of kernels:

 * Monolithic: The kernel consists of one unbreakable unit module. It's common for older Linuxes (older than 2.0) and UNIX systems.
 * Hybrid: like Windows – permissions can be set. Hybrid kernels are basically microkernels in which some "not important" code parts have been moved from user level (userspace) to kernel level (kernelspace) using fewer abstractions to run faster.
 * Microkernel: Kernel is in multiple small programs, not in one big module.
 * Modular: The modular kernel tries to fix the monolithic kernel's problems. Parts of the kernel - physical and logical - and modules created by this, which are mostly drivers can be loaded into memory. It saves the size of the kernel, but both together becomes bigger and bigger (its size is relative though, it depends how many drivers do you want to add, complete kernels are mostly around 100 MB or above, but if you are minimalist, it can be under 10 MB). We put modern Linux systems under the modular term (to be punctual, Linux kernel is monolithic modular). The kernel modules can be found in /lib/modules/kernel-version folder.

Place of kernel: It's in the /boot folder, and there are soft-links to vmlinuz and initrd in the root.

Filesystems
At filesystems arrays have huge role in Linux.

Virtual filesystems (for the system)

 * SMBFS, SSHFS, NFS, etc.

Supported filesystems:

 * ext2, ext3, ext4 (own filesystem of Linux)
 * ReiserFS, Btrfs, ZFS, XFS
 * FAT32, NTFS
 * stb.

Directory structure

 * Hierarchical
 * directories (folders)
 * files

Single-level directory: Commodore floppy; magnetic tape

 * Path
 * Root: /
 * e.g.: /home/joe/myfile.txt
 * Connected (mounted) media
 * e.g. /mnt/usb
 * Mounting:
 * (if we want to use CD-ROM)
 * , where -ta indicates automatic detection of the media's type.
 * The sda,sdb, sdc… indicates the HDD,SSDs, and modern distros mount them to /media/[partition name].
 * Unmount / disconnect:

Main folders

 * /bin, /sbin
 * executable, binary files (only admin can run sbin programs), no file extension needed
 * /boot
 * system startup files: GRUB, LILO, kernel (/boot/vmlinuz)
 * /cdrom, /media, /mnt
 * media mounting: USB, Floppy, CD/DVD
 * /dev
 * we can reach the devices through files e.g.: /dev/dsp (soundcard) /dev/cdrom (CD) /dev/sda2 (first HDD/SSD's 2nd partition)
 * /etc
 * configuration file
 * sysadmin has only access to it
 * global configuration folder
 * /home
 * users' folder
 * user's files
 * settings, configuration files, folders
 * for eg.: /home/peter /home/peter/documents
 * /lib
 * shared objects, libraries
 * like DLL files in Windows
 * kernel modules
 * /lost+found
 * damaged files
 * recoverables
 * /proc
 * currently running operations - numbered by files and information of the system(processor, memory etc)
 * example command (processor information):
 * /tmp
 * location of temporary files
 * both system and user level
 * /usr
 * location of user files
 * programok installed programs
 * libraries
 * sources (kernel): /usr/src
 * documentations: /usr/share/doc, /usr/doc
 * icons, and so on.
 * /var
 * collection of services
 * cache(temporary storage): /var/cache
 * log files: /var/log/maillog
 * email accounts (mailbox): /var/mail/root
 * www folder: the default webpage folder of apache (/var/www)

Users

 * system administrator: root
 * users: „root” user creates them basically
 * users can be grouped
 * permissions can be given in the filesystem
 * e.g.:
 * The first user has also root permissions (which you set in the installation) - but this depends on distribution, e.g. Debian users have no root permission by default, and there is no sudo.

title: Linux Basics/The structure of Linux


text:
Linux Basics/Graphical interfaces

X Window System does the job for graphical display under Linux. We also call X Window System as X or X11. Its GUI is very plain, but it's a graphical server, so it gives home to many desktop environments and window managers. Login can be on graphical interface:XDM(X Desktop Management), GDM, LightDM, SDDM etc. Every operating system has its own graphical package manager, like Synaptic under Debian-based systems, Fedora has dnfdragora, Arch has Pamac or Octopi, etc.

Important Desktop Environments and their logos: There is also Cinnamon and MATE which can be mentioned, they're both Gnome-derivatives. (Arch wiki has all the Desktop Enviroments explained) You can choose which you want to install under Linux, customization has no limits.

Composite Window Managers e.g.: Compiz, Compton, Xfwm, Marco, KWin.

The Window Manager does the job for window operations (minimize, maximize, move etc), compositor does the effects, like at minimizing the window slowly vanishes etc.

You can change the Window Manager and Desktop Environment under operation (but when you install them, you may have to quit from the current DE and re-login to see the changes)

title: Linux Basics/Graphical interfaces


text:
Talk:End-user Computer Security/Main content/Some measures that are primarily physical

Metal boxes or containers (such as briefcases) lined with metal foil, have the potential of shielding malware RF communications
After performing some experiments, completely wrapping a mobile phone in metal foil does indeed appear to block mobile-network, WiFi, and Bluetooth communications to and from a mobile phone. However, if there are some slight gaps in the wrapping, there is the chance that the blocking might fail. Anyway, with such principles certain metal boxes might be automatically capable of performing such shielding. For metal boxes that have the gaps just mentioned, covering over those gaps with metal foil (such as cheap aluminium foil used for cooking), might provide sufficient shielding to make the whole box a shield for the contents of the box. Likewise, lining containers such as briefcases with metal foil has the potential of turning the containers into shielded containers.

Perhaps such information should be integrated into this chapter, perhaps under the "Metal boxes", "Padlock-able laptop bag", and "Combination lock briefcase" sections. If doing so, linking to the "Wireless Communications" chapter may be a good idea—see the note here.

When using planar materials, unrepeatable-pattern principle can be better if...
With respect to the "Perhaps the simplest and best idea" subsection of the §"Tamper-evident security-system ideas" under §"Exploiting unrepeatable patterns for tamper evidence" of this chapter 5 (labelled "Some measures that are primarily physical"), it can be better to use transparent or mesh materials, and then to layer such materials on top of each other. The non-opaqueness and the layering, induce unrepeatable patterns in security photographs taken, that have stronger unrepeatability. For example, why not layer several layers of translucent shell-suit material?

Additionally, if you use a material that makes use of a variety of colours that is on the material in a haphazard fashion, this can result in greater unrepeatability. If you further choose unusual colours, and maybe some metallic colours (like silver), shimmer colours, and/or iridescent colours (like the appearance of the underside of CDs), this can result in even greater unrepeatability. The use of holographic materials and/or irregularly textured/bumpy materials might result in even more unrepeatability. These things can perhaps be induced by the simple application of a variety of art paints in a particular way.

Unrepeatable-pattern principle can be better if a special type of photography is used....
Using X rays or T rays for the security photography recording the unrepeatable patterns can be better where patterns have a 3D aspect. An adversary may think that the only pattern to duplicate is the one that is visible. But if you use X rays or T rays, the recorded pattern may be at some depth that only you know, making it even harder for an adversary to repeat the material configuration such that the repeated configuration also repeats the same X ray or T ray patterns.

Also, even without a 3D aspect in the unrepeatability patterns, other electromagnetic photography can be used for potentially improved security. For example, could RF distortion induced by some unrepeatable-pattern configuration be captured as security images?

These ideas link to the ideas present in §"Measuring physical properties for authentication" in the "Broad security principles" chapter.

Potentially better terminology to use, and other potential improvements, for §⟪Specifically for goods in physical transit⟫
A web-page on the puri.sm website uses the term 'anti-interdiction' to describe measures aimed at preventing and/or detecting MITM (man-in-the-middle) attacks during the transit process. It might be worthwhile using this terminology in this section to align better to the terms used in the "secure computing" community. There is also potentially useful info at the web-page that perhaps can be added to this book, and in particular to this section.

Research around “main idea” sub-section.
  Photo of pattern bits and pieces that tended to form patterns not readily destroyed enough in the opening of the security container
 * In respect to the adding of shredded optical discs such that light-refraction distortions are added to the unrepeatable-pattern material, I found it to be not so effective, probably because refraction distortion/deformation wasn’t strong enough. Iridescence effect (“rainbow” effect) from shredded discs, was probably considered not significant enough in light of the effects obtained from the combination of transparent pieces, colour-tinted semi-transparent pieces, and reflective pieces.
 * Adding colour-tinted semi-transparent bits to the mix is likely important for increasing pattern complexity, and for making it harder to duplicate the pattern. If the bits can be shaped so as also to create visual deformations/distortions (like the refractive distortions of a glass sphere), then this would probably improve security even more. Have tried creating colour-tinted transparent bits using sugar and water heated up into a kind of gel that afterwards cools to become solid. Certainly it works in terms of creating such semi-transparent coloured bits, but such bits end-up being sticky, which is undesirable—it means that the security patterns tend not to be disturbed upon removing the secured item from the container (because the bits stick together). If the solution turns into caramel then the stickiness is not there, but then there is invariably a brown tint, which is undesirable from a “colour variety” point of view. Recipe used was approximately: mix together 2 level teaspoons of white sugar, a little paint (for the colour tinting), some water, and a small bit of oil; place in microwave for one minute, and then drop hot liquid on to an oiled surface to create several separate ‘islands’ of the liquid; leave to cool. To overcome final stickiness, I did try coating with varnish, and some other things, but mostly it didn’t seem to work. I thought that perhaps the sugar blobs were sticky on the outside due to the presence of water, so I tried placing them under the grill in an attempt to remove the water from the outside, but it didn’t work to remove the stickiness.
 * Crystals of sugar are not sticky, so how about trying out the making of coloured transparent sugar crystals? Could perhaps work but not sure how to make them. Are copper sulphate crystals made through electrolysis? Could that possibly indicate a path forward?
 * Shattered glass/plastic coated with coloured varnish might be cheaper and easier to make than trying to make colour-tinted sugar blobs. Could perhaps use old CD cases, bubble-wrap pieces, or old spectacles. CD cases seemed inappropriate probably because of its rigidity, and because the shapes produced tended to interlock rather than tumble; such characteristics probably meant that patterns were not easily destroyed upon taking out the secured item (such easy destruction is desirable). Broken glass/plastic from spectacles likewise would probably have the same problem. The friction between bubble-wrap pieces also tends to prevent the security patterns from easily being destroyed. Light pieces also have a tendency of not easily tumbling nor moving; probably the weight of rice grains means that the grains much more easily tumble and move around. Material that tumbles rather than material with friction, interlocking shapes, or a very light weight, is desirable. Rice appears to be such material but it is not transparent and any semi-transparency in it is both quite low and unyielding to being able to bear a variety of coloured tints.
 * Coloured jelly broken up into bits and pieces might work when the item being secured only needs to be secure for a short while, perhaps up to a couple of weeks. The wobbly and flexible nature of jelly means that patterns can perhaps be more unrepeatable and more easily destroyed. By mixing paint in with the jelly, different tints can be created, thereby increasing the pattern complexity and pattern unrepeatability. However, after having left some gelatine jelly solution for a long time, it smelt quite rank, so perhaps jelly would only work for a short while (as just mentioned). Ideally, the bits shouldn’t decay. In this regard, plastic that doesn’t degrade easily, which would otherwise be thrown out, would seem to be good material.
 * If some of the particles/pieces are metallic, and the submerged item is magnetic, then perhaps the removal of the submerged item would more likely result in disturbance of the unrepeatable patterns. Alternatively, static-electricity attraction can be used instead for similar effects.
 * A lubricant or teflon-like spray (maybe furniture-polish spray or WD40) could perhaps be used to make bits very slippery so that they do things like tumble very easily, ensuring that the patterns are destroyed more easily when trying to get to the secured item. Did try furniture polish but it didn’t work with paper-like bits. Think I may also have tried WD40 but again it probably didn’t work with such paper-like bits. If instead WD40 (or some other lubricant) were applied to rice, that might be more effective, that might make the rice tumble more easily.
 * Perhaps adding hair or string, multicoloured by use of differently coloured paints, could increase the pattern complexity and unrepeatability. I have managed to do this for string. String seems to retain its shape quite easily. It probably would be good if the shape of the material sprung into another one upon disturbance—maybe in this regard, fairly-stiff nylon or hair could be better.
 * Perhaps multicoloured rice would work well. But once again, because of the lack of transparency in rice, rice probably wouldn’t be so effective.
 * In order to add a coloured tint to transparent plastic wrapping-type material, paint can be used. However, such plastic that already has a tint may be preferable, as such plastics seem to be more transparent (certain “assorted chocolates” sweet wrappers work well, such boxes of chocolates may also furnish one with good reflective foil having a variety of coloured tints). Have been trying to add tints with paints, and am finding that often the transparency is impaired, probably because of the composition of the paints I am using—they’re not specifically designed for transparent effects I suppose, special paints for transparency would likely be better (maybe glass paints?) Did think about using diluted acrylic paint, built-up using several layers, but probably the transparency issue would still be there with such a method—the paints I am using are probably just not designed for creating transparency effects. Diluting with varnish or water has made painted areas lumpy and streaky, both when the paint has been acrylic paint, and when the paint has been oil paint. Diluting/thinning with white spirit (or turpentine) perhaps could help but I think the same transparency issue would still likely exist with such methods. I have tried diluting oil paints with oil but still can’t achieve the good colour-tinted semi-transparency effect I desire; such diluted oil paint also takes a long time to dry.
 * Perhaps precision in terms of camera positions and angles, is not needed in respect of the security-image photographs. Instead, a video that rotates its viewport all the way round the item, first in the longitudinal direction, and then secondly in the latitudinal direction, can possibly be used. Such videoing may also be a better way to make sure that the entire surface of the container is visually recorded. To effect such a video, rather than rotating the camera, one could possibly have a smartphone camera fixed on a table surface, pointing upwards, with the container rotating above the camera. Closing curtains and using the mobile phone’s flash would probably both be good things to do in respect of reflections from the unrepeatable-pattern material that would otherwise vary in relation to differences in the scene lighting.
 * A sealable transparent flexible pouch may be better for security as more pattern destruction would likely take place after taking out the secured item from such a container. Tinging the pouch with random burn marks, along with deforming it in random ways, might make the bag/pouch itself unrepeatable. If the bag can then be sealed shut (perhaps with glue) such that the bag itself constitutes an opened-evidence mechanism, that could provide even more security. Gluing the container shut can also result in extra security by the greater disturbance of the unrepeatable-pattern material inside the container. Such extra security comes about from the principle of there being greater pattern disturbance in the contents, during the opening of the container. Not all set-ups perhaps would have such a principle in play, and maybe special effort would be needed in the designing of the container to ensure such a principle would apply to the relevant set-up.
 * What if an adversary uses a glue to recreate the precise security patterns, and the glue has the property of evaporating without trace and without disturbance of the precisely recreated patterns? Perhaps using vaseline mixed with differently-coloured paints in the patterns would mitigate against such an attack. The inside surfaces of a transparent pouch could be lined randomly and unevenly with such multicoloured vaseline. After filling the pouch to the brim and beyond with bits, and then closing the pouch tight shut, the bits would disturb the random lining of the multicoloured vaseline. Upon retrieving the secured item, probably the lining patterns would be slightly destroyed, and furthermore, upon trying to reseal the pouch such that it looked like it had never been opened, the lining patterns would likely change even more. Tamper evidence would thereby be induced through such pattern changes in the multicoloured vaseline lining. I did consider whether toothpaste, purely paints on their own, or ultrasound gel mixed with paints, could be used instead of the vaseline-paints mixture just mentioned. Both toothpaste and paints on their own would likely dry out to become hard, making them unsuitable. Ultrasound gel with paint mixed-in works in the short term (over a couple of days) apart from the action of gravity over time, which can destroy the patterns. Vaseline mixed with paints seems to be the best and so far, from experiments, has seemed to have worked over the course of fourteen days (from 17.9.2020 till 30.9.2020)—the patterns seem to have not changed at all. At the end of the testing period, the vaseline was still soft and pliant, meaning that the security patterns formed by the vaseline could still easily be destroyed by disturbance—therefore it was still good for creating tamper evidence after disturbance.
 * After experimentation, I have found there is a problem when the security-pattern material is mostly coloured paper and the like, in that the patterns are not being adequately destroyed during the opening process. Having a ‘splurge’ effect, such that the contents ‘splurge’ out of the container upon opening, probably would improve things. Squeezing the unrepeatable-pattern material into the container, theoretically would beneficially work for creating such a ‘splurging’ effect. But I am having difficulty achieving this. Have tried squeezing (and compressing) pieces from flexible plastic material (such as plastic bags). They do indeed readily expand from a compressed state when the pieces are each on their own, but when you compress a whole bunch of pieces together the expansion rate is not so great—they resist expansion owing to the weight, and inertia of all the pieces together. The contents simply do not ‘splurge’ out; instead, they are just slowly expanding only a little. Adding compressed metal springs in the container could help to achieve the desired effect—a bit like a jack-in-the-box toy. I have tried using a small metal spring from an old pen for this, to improve the “splurging” effect. Closing the container with the spring adequately compressed and adequately positioned, seems to be difficult, and I found it difficult to improve things with the spring from the pen. More broadly, any material having springy (a kind of elasticity) attributes may help to achieve this mechanism. I have tried old kitchen sponges greatly compressed, but the “splurging” effect was just not much improved—still slow. If the container were stretchable and if when the item(s) were secured, the pouch became stretched, that could help facilitate the ‘splurging’ effect. Have tried gluing elastic bands to the inside of such a pouch in order to simulate such stretchability, but the super glue I used wouldn’t work for the sticking of such surfaces—using glue-gun glue might be better . Also have tried using elastic bands around the outside of a see-through pouch, but that has also not improved things much either. Stretched elasticity that has a stronger strength to return to its unstretched state, could improve things, but I’m slightly unsure as to how to create such stretched elasticity in the container, such that the container remains stretched during the time items are secured in the container. Maybe compressed rubber (such as exists in a compressed rubber ball) and/or transparent balloons might be capable of creating such elasticity. Anyway, so far, any ‘splurging’ mechanism I’ve managed to foster, has simply not been strong enough. One of the other problems appears to be that the security-pattern bits I am using have too much friction (maybe they are even a little sticky), and are quite light in terms of weight. Probably largely because of this, the patterns are tending not to be destroyed as much as I would like. Heavier bits like raw rice grains, probably would be better. Rice additionally has a tumbling effect, which is desirable, and I suppose rice can be coated with a lubricant to accentuate the “tumblity” of the grains. Perhaps I could instead try coloured rice in a see-through bag that is rolled-up, where hopefully the unrolling process (which is perhaps needed to get to the secured item[s]) inevitably destroys the patterns to a sufficient-enough degree. But then rice is not much transparent, perhaps meaning resultant patterns aren’t as complex as is required for the security protocol to work sufficiently. Additionally, rolling-up the bag means the surface area making up the pattern images in the security photos is reduced, meaning the patterns are not as complex as they are with bags not rolled-up. Raw rice grains appear to be sometimes semi-transparent; perhaps extremely strong light shone through the grains could create a strong-enough transparency effect in the rice for complex-enough security patterns to be induced. At present, these problems have been significant enough to make me feel as though I have to ‘go back to the drawing board’ with my ideas—it is very much necessary that the unrepeatable security patterns are readily destroyed upon opening the container.
 * If securing just one item, it is better to split up the item into several parts (if possible), where each part is submerged separately in the unrepeatable-pattern material, with the parts spaced apart. This generally improves security because retrieving all the parts then causes more pattern disturbance. If doing such, boxing the parts with radiation-shielded boxes might be a good idea so that adversaries are not then able, through the use of non-invasive scanning equipment, to figure out easily which boxes contain parts vulnerable to tampering attacks. If an adversary were able to do such, they would then possibly be able to tamper with just the key part, and then place the part back into the container without disturbing much the rest of the pattern mix. If on the other hand, they weren’t able to do such, there would be an increased chance that they would have to open every single box, thus resulting in greater security pattern disturbance, which would therefore provide a generally better system of tamper evidence.

==== Research around “Speculating stronger security again with unrepeatable-pattern principle” sub-section. ====
 * Did consider whether a glass of water with coloured oils on its surface, kept completely motionless, could be used for keeping a water-proofed memory stick submerged in it (as a tamper-evident mechanism). A person would photograph the surface patterns, and the photos generated would then be the security-pattern photos. However, when I tried using oil paints for the oils on the surface, it didn’t work—the patterns changed regardless of disturbance to the liquid. Also tried candle wax, but that too didn’t work (probably also tried wax mixed with oil, with the same unsuccessful outcome). Instead of coloured oils, I tried pencil-shaving fragments (probably on top of a film of oil on the water’s surface) but that too didn’t appear to work. A suspension of coloured fragments in a transparent liquid could work well but then the fragments would have to be motionless. How about the oil salad dressing bottles that I think you might see in restaurants? Do they have bits suspended in the oil? Could that perhaps be used? Skin on milk could perhaps be used, if it is easily destroyed when trying to get to the contents. If skin could be created for all inside sides of a transparent container, that could be really good.

Research around “Perhaps the simplest and best idea” sub-section.
After experimenting with crumpling plastic bags, I have realised that such material is too shape retentive—the crumples tend not to be destroyed easily. The same may well be true also of shell-suit material. In light of such undesirable properties, I have instead employed the use of silk and silk-like fabrics for such unrepeatable-patterns security. So far, over the course of weeks, it is proving to be effective. One issue is that the fabrics can easily move if they are not secured in place—I have managed to secure them successfully in place, by tucking the fabrics under and between items in the secured area, such that they are pinned, in some fashion, in place. For making sure the patterns haven't changed, I take two photos each with the flash on. The first photo is the historic record of how the patterns should be, and the second is a "latest" photo which enables a check to be made on whether the patterns have changed since the time of the first (historic) photo. By simply switching back and forth between these two photos on my digital camera (which could also be done on a conventional computer), I am able to detect easily, just through standard human vision, whether the patterns are enough the same to conclude that no intrusion into the secured area has occurred. The use of the flash means that I mostly don't need to worry about other light sources disturbing the security images. Using reflective un-patterned silk might be better than other materials: with the flash on, photography can capture a kind of topographical mapping of the subtle "hills and valleys' in the reflective un-patterned silk, which can make the security patterns stronger.

I speculate that using a clear plastic/glass sheet to go in front of, or around a secured area where this kind of unrepeatable-patterns security is employed, could be a good idea. Its purpose would be twofold: 1) it could stop people from accidentally disturbing the security patterns (especially if the sheet is screwed-in place); 2) if fabrics are pinned just by the force of the sheet, somewhat haphazardly behind the sheet, this may result in stronger security patterns that are more easily disturbed when getting to the secured area (such getting would involve the removal of the plastic/glass sheet, and so probably would also cause the 'tumbling down' of the fabrics—with related security-patterns destruction— to some extent). Such an idea could be applied to a briefcase or similar container, where the container is made partly transparent or a transparent container is specifically acquired. It could also perhaps be applied to glass display cabinets.

Research around new ideas not yet in the book.

 * The electrical resistances measured between random point pairs could perhaps provide configuration information that would provide an alternative to the use of security-pattern images (the main method that has been researched thus far). The unrepeatable-pattern material would then be made up of bits and pieces of electrical conductors, perhaps of materials of varied resistances, and perhaps together with some electrically-insulating bits and pieces. Such security could be much stronger than the application of the unrepeatable-pattern principle to visual images (such application being what has so far been investigated).

 Photo of transparent plastic pouch filled mostly with transparent or semi-transparent pieces of fabric-like plastic material, with light being shone from the underside into the pouch —looks like an X ray, doesn’t it?
 * Somewhat similar to the measuring of electrical resistances, is shining a light through a transparent container and capturing the image created on the other side, which could perhaps simply be the shadow cast. Such images could provide strong security, and could even be implemented in addition to implementing the conventional image security so far discussed in this research, with both implementations in operation for the same security container.
 * Rather than the unrepeatable-pattern material filling all the empty space in the security container, I have developed a new idea that involves lining an inflated balloon with unrepeatable patterns. A transparent balloon ought to be used, so that the lining patterns are visible from the outside when the balloon is inflated. The lining patterns can be formed in the same way as already mentioned for the creation of lining patterns for certain other situations, by creating multi-coloured vaseline (using paints mixed into vaseline), and then creating random patterns on the inside lining of the balloon before it gets inflated. To make the application of the multi-coloured vaseline easier, you might be able to turn the uninflated balloon inside out, apply the vaseline, and then turn it back to its normal form where it is no longer inside out. The item to be secured would need to be placed inside the balloon, probably before inflating—might need to stretch the balloon opening to get the item into the balloon. Once the balloon has been inflated, hopefully the multicoloured-vaseline patterns (the security patterns) would be formed on the inside lining of the balloon, and become photographable. The balloon would have to be sealed in such a manner that any possible air leakage would not unduly destroy the patterns during the time the item was secured. For such sealing, you could perhaps use some well-suited glue (maybe glue-gun glue ). With such a set-up, it probably would be very hard not to destroy unnoticeably the balloon-lining security patterns in the process of performing any tampering to the secured item (inside the inflated balloon). Trying to recreate deceptively the security patterns in the same set-up, would also likely be hard. Therefore, such a set-up perhaps would constitute quite an effective tamper-evident system. Instead of using multi-coloured vaseline, multi-coloured hot wax could perhaps be used, where the wax would be poured before inflating, and then the balloon would be quickly inflated shortly after such pouring; the wax would cool to form the security patterns on the inside lining of the inflated balloon. Alternatively, PVC glue mixed with different paint colours could be used to line the balloon; once the PVC glue dries on the inflated balloon, there would then hopefully be a coloured pattern lining, that upon deflation would be destroyed. Confetti balloons, or the mechanism behind such balloons, where the confetti is "activated" so that it sticks to the lining of the balloon, might also work; after inflating such balloons, it appears creating an electrostatic charge on the balloons by rubbing them on some wool (maybe also on your head might work), makes the confetti stick on the inside of the balloon; such patterns might be hard to replicate, and also easily destroyed through a small change in the volume of air in the balloon. Recent experiments have indicated certain types of torn-up plastic wrapping material (like from plastic bags), as well as hair, are capable of sticking—like the confetti of confetti balloons—to the inner balloon lining using electrostatic attraction, for several days, in fixed unchanging positions, regardless of the natural gravitational attractions that would otherwise move them. Figuring out the plastic materials amenable to such electrostatic "position fixing" might not be so simple, so am first going to experiment more with just human hair (could be cheap source of material... just cut your own hair?) Upon reflection, if applying multicoloured vaseline patterns to the inner lining of a transparent balloon, there doesn't seem to be much of a reason not to also fill the empty space in the balloon with other "conventional" unrepeatable-pattern material. Such would seem to increase generally the security deriving from unrepeatable patterns in the set-up. If doing such, it might be a good idea not to fill the balloon to the brim with such material, so that there is likely greater "fluidity" in the stuffing (in contrast to if it were ram-packed with the material), and so greater ease for security pattern destruction as part of the mechanism for detecting tampering. However, if not enough material is put in the balloon, then the patterns could be destroyed regardless of tampering, so need to make sure not too little material is added. Something not addressed thus far, is how to get the item to be secured, into the balloon. For small items, such as certain memory sticks, such items may fit through the 'blowing-up' nozzle relatively easily. But for larger items, it may not be possible to insert them into the balloon in the same way. One possible option perhaps is to slit the balloon open at the bulbous part of the balloon, insert the item to be secured into the balloon, and then glue the slit closed such that the balloon can then still be blown-up in the conventional way—such would be a bit like performing a surgical operation on the balloon. The kind of glue used would probably be important—perhaps glue-gun glue would work for this . Another thing to bear in mind, is that if the balloon is blown-up so that it is very close to its maximum capacity, this might provide greater tamper evidence due to it being very sensitive to bursting (such bursting perhaps perceived as causing 'mayhem' of sorts in terms of destroying the security patterns).  Instead of using inflated balloons, inflated bubble-gum bubbles could perhaps be used to improve security. Once such a bubble is burst, blowing-up a bubble with the same patterns as the burst bubble, is likely practically impossible. Not sure how such bubble-gum bubbles would actually be practically effected, as such bubbles would likely tend to be quite delicate—perhaps requires greater thought and research in order to make such a mechanism practically possible.  It seems that opaque balloons can sometimes be used, just by shining a strong torch light (such as maybe a smartphone torch light) through an inflated balloon in order to reveal the inner-lining security patterns. The patterns must be capable of being revealed in this way, and so the substance used for making the patterns, may need to be partially transparent. Also, the balloon not being empty, may undermine the security if it be the case that the torch light can't get sufficiently through the balloon. Being able to use "ordinary" opaque balloons that are likely more common, may be especially good for budgetary reasons. Could also be good for security, as the patterns aren't normally compromised to adversaries if they simply pass by—the patterns are not visible to casual passers-by, a strong torch light is required to make the patterns visible.
 * The unrepeatable-pattern material could be formed from multi-coloured iron filings in water. The transparent container would be wrapped completely with transparent magnets. The multicoloured iron filings would then be attracted to the panels of the container in a random way. Once the filings become settled into their ongoing fixed positions stuck to the outer walls of the container, photos of the outside of the container would then be able to be taken, such photos being of the security patterns visible from the outside of the container. To get to the container’s contents, hopefully the outside magnets would have to be moved, and that would hopefully noticeably destroy the security patterns. This security method is perhaps prone to the attack where both the iron filings are glued to the container to repeat a particular pattern, and the glue used ends-up dissolving in the water to leave no trace that glue was ever used. On another note, a water-cooling PC case that is transparent, might be able to be adapted such that it constitutes the basis of the security container of this security method.
 * Electrostatic or magnetic attraction could perhaps be used in conjunction with some suitably-fine material, such as perhaps hair in the way it is affected by electrostatic charges. But gluing the material, in such a way that the glue evaporates, might be capable of defeating such security. If the electrostatic or magnetic charges could be randomly distributed, and then somehow set-up to be lost upon opening the container, then maybe that would be able to overcome such attacks (since the specific charge distribution would perhaps then not be able to be reused or recreated for any hoax). Cling film might be material easily capable of having randomly-distributed electrostatic charges (the distribution may even be "naturally" created). You could, for example, instead of draping storage boxes with cloth, drape them with cling film having short cut strands of hair randomly positioned on the underside of the cling film (other underside materials that might also be used are the material formed by small pieces of plastic-bag material, dust, and talcum powder [perhaps multicoloured using paints or otherwise], when the material is capable of electrostatic attraction [in the case of dust and talcum powder, good security might also be possible without electrostatic attraction]). The hair material would hopefully stay in position due to the electrostatic charges in the cling film, and also hopefully be easily moved by slight physical disturbances such as those perhaps made by intruders. Adversaries wouldn't be able to spray a conventional kind of glue to keep the hairs in place, because the hairs would be on the underside of the cling film (where any spray cans or like dispensers should find it hard to reach). The physical shape of the cling film, perhaps slightly crumpled, maybe also slightly warped, would also lend to making it hard to deceptively recreate the same security patterns—the cling-film shape, in addition to the hair arrangement, would also make-up the security patterns. It might be that the randomly-distributed charge in the cling film is easily modified through slight physical disturbances; if this be the case, such property would make this method even more secure.
 * How about having a memory stick wrapped-in cellophane left in a transparent container of water, where moss or algae is allowed to grow all over it. Perhaps taking the stick out would invariably noticeably destroy the moss/algae patterns such that they could not unnoticeably be repaired. Reproducing the moss/algae patterns would perhaps be practically impossible because of the way the moss/algae grows. Perhaps the only problem would be how to freeze the moss/algae patterns such that they stopped changing. Could a microscope perhaps be used to make sure the patterns hadn’t undergone tampering?
 * Perhaps the container could be some kind of irregularly-shaped electrical capacitor storing charge. Some random action could somehow disturb the charge into an unrepeatable pattern. A “photograph” of the charge could then be taken as the security photo (maybe of the EM fields?) Opening the container invariably disrupts the charge and consequently also the security image. The random nature of the pattern perhaps means that it is hard to reproduce artificially. Cling film might be good for keeping a randomly-distributed electrical charge (it may even be naturally able to have such distribution). Such distribution might also be capable of being easily lost.
 * Can cracks in transparent glass be repaired such that it is unnoticeable that the cracks were ever there? If not, then maybe glass could be used somehow. Encasing in molten glass might be capable of providing a tamper-evident solution. Instead of glass, perhaps plastic could be used, such as perhaps acrylic plastic. Transparent acrylic can be bent by using standard heating equipment meant for such bending; such heating equipment appears likely to be inexpensive as well as easy to use ; according to https://plasticsheetsshop.co.uk/how-to-bend-perspex/, acrylic can be bent using a hairdryer, an adjustable paint burner or a convection oven (if you don't have the standard equipment) . It may be possible to use plastics other than acrylic, that are more readily available. For example, it might be possible to recycle the transparent or semi-transparent plastic found in old CD/DVD cases (am assuming that such plastic is not classed as acrylic) for this security mechanism. The Wikihow "How to Melt Plastic" article indicates that household plastic can sometimes be melted in a kitchen oven, with a heat gun, or with household nail polish remover (acetone). Bending acrylic completely around the item to be secured, both in the latitudinal and longitudinal directions, might work. Rather than using completely transparent acrylic plastic, if “fleck glitter” acrylic plastic were instead used, it would perhaps be then capable of providing unrepeatable patterns without requiring any extra work (if it were the case that the “fleck glitter” patterns were of a random nature in the acrylic). "Fleck glitter" acrylic plastic appears to be currently relatively expensive; instead, it would seem just painting the inner sides with glitter nail-varnish polish should work; brief research seems to indicate that unbending the plastic through heat would likely melt the "nail-varnish polish" patterns, and therefore this would seem to add to the tamper-evidence mechanism. But then how to prevent the bent plastic from being unbent, and then bent back again, in an unnoticeable way? Perhaps painting the bent acrylic with some material that noticeably changes when heated-up could overcome such an attack (glitter nail-varnish polish might work) . Then any heater used to unbend the material would destroy such patterns. Perhaps simply using a file on the bent acrylic would work. The filed acrylic would hopefully create a rough texture with a pattern hard to reproduce/imitate precisely, especially in combination with the “fleck glitter” patterns. Heating the acrylic would then hopefully melt the rough texture created using the file, and so destroy the security patterns formed through the filing. Either some types of thin acrylic, or all types of thin acrylic, appear likely to shatter; I've gathered this from the comments of others; such easy shattering could add to the tamper-evident mechanism.  This idea works along the hypothesised principle of it being difficult to conceal unnoticeably cracks and topological cuts in transparent glass/plastic. It is considered that this might not be true (for example) with glue-gun glue: it could be possible to cut a solid piece of glue-gun glue in two, and then bond them together (through slight melting of their ends) so that there is hardly any evidence that the piece was ever cut in two. This idea could mean that tamper-evident mechanisms that rely solely on glue-gun glue, might be able to be circumvented through such cutting and re-bonding. Adding a swirl of contrasting colours (perhaps using paint) to the glue-gun glue, as well as adding glitter (glue sticks are actually available that already have glitter in them) could improve things, but still, it might be that even with such measures, such tamper evident mechanisms would still be able to be circumvented in the just-mentioned way. One possible way to overcome such defects and weaknesses, is to mix wax in with the glue-gun glue (maybe multicoloured wax) so that the wax regions and the glue regions in the conglomerate, have boundaries escaping easy encapsulation. Such a mechanism would rely on the fact that wax has a lower melting point to the glue-gun glue. Adversaries trying to do any topological cutting and then re-bonding, would probably then have a rather tough time concealing such cuts because the melting and re-bonding process would be hard to control as a consequence of the wax becoming runny in the melting of the glue.
 * Rather than a rigid container that simply has a lid, a special container that falls apart completely when it is opened perhaps would improve security, because there would then likely be greater destruction of the security patterns. Something like a house of cards where if one of the cards at the bottom is taken out, the whole structure collapses. Or perhaps like a cardboard box that easily collapses to cardboard only existing in one plane, from a 3D box to a 2D cut-out for the box. Using hinges might be useful in the construction of such containers. Following this same idea of a container falling apart, some material that when it develops a crack, cracks all over the place such that the whole structure disintegrates to some extent, could also improve security along a similar vein—a bit like an egg shell but maybe more fragile. Certain kinds of extremely fragile glass perhaps have such properties.
 * Transparent hair gel might have been suitable, but then it might be possible, with very sophisticated equipment, to lift out a section of the gel, and then put it back-in, without any disturbance to the security patterns occurring.
 * In respect of inducing a greater destruction of security patterns during the retrieval of secured items, perhaps having the item to be secured placed in liquid, where a buoyant layer of solid bits is trapped beneath the secured item, and a sinking layer of solid bits is trapped above the secured item, could work. The natural tendency is for the sinking layer to go to the bottom, and the other layer to the top, but for the security device the layers are in some sense in the opposite places to “where they want to be”. When secured as such, there is a natural tension between the layer of bits “wanting” to go up, and the layer of bits “wanting” to go down. Removing the secured item perhaps invariably causes such disturbance that both layers get disturbed with the layer wanting to go down, to some extent (perhaps completely) going down, and the opposite with the other layer. The security patterns then would thereby be destroyed, hopefully more than with other methods, and perhaps even in a total way. Such a set-up would perhaps solve the recent problem I’ve been experiencing concerning the security patterns not being sufficiently destroyed. The theories behind the sedimentation of sea beds, and the use of centrifuges, seem applicable here.
 * If it is possible to surround items to be secured with long-lasting bubbles that keep their positions, then that could perhaps be a very secure unrepeatable-patterns tamper-evident mechanism. Getting to the secured item would invariably destroy or at least alter the configuration of the bubbles. Bubbles with long lifetimes seem possible (see http://www.recordholders.org/en/list/soapbubbles.html). Instead of bubbles, a kind of honeycomb-like architecture formed by the soapy material of bubbles, within the cavity between a secured item and the outer casing of a transparent rigid plastic box, might may also work.
 * A plastic box containing some fragrance that is lost just a few seconds after opening the box, could perhaps provide security. To overcome the potential attack of an adversary deceptively putting the same fragrance back into the box, a very unique fragrance could perhaps be used. Such a mechanism would probably thwart the attack where there is the inducement of a different "air" composition in the opening of the box through the use of laboratory conditions, contrived so as to try to circumvent the security mechanism. For example, such attacks perhaps would work where colour-changing chemicals form part of the security mechanism, and where colour changing doesn't occur when the box contents is exposed to pure nitrogen (instead of air). The problem with using a unique fragrance is how to make it such that an adversary is unable to duplicate it. Anyway, this idea exploits the nature of gasses, and that once a container of gas is opened even for a very short amount of time, it's likely very difficult to prevent at least a bit of it escaping. This general security idea of using gases in such ways, appears to be important, and perhaps can be adapted for a variety of security mechanisms.
 * Another potential way to use balloon or similar stretchable material, is to stretch the rubber-like material so that it is stretched under tension completely around an item to be secured, with cut short strands of human hair randomly placed underneath the material to cover the entire surface of the item with visibility of the hairs on the other side of the stretched material, and so that the material is closed (perhaps tied) so that it persists in a stretched and unchanging state around the item to be secured. It's a bit like putting the item to be secured in stretched tights (perhaps). The hair placements, visible even though underneath the stretched stretchable material, would constitute the security patterns. Short strands of hair perhaps constitutes good unrepeatable-pattern material because of its nature of being easily changed by slight things in combination with also having some persistence in respect of its positioning. Because the stretchable material is stretched around the item to be secured, trying to get to the secured item would likely inevitably make part of the material un-stretch and such un-stretching would likely disturb the security patterns. Trying to recreate the same patterns would likely be extremely difficult because of the conflicting forces between the unstretchable yet flexible hair and the stretchable material (such conflicts existing particularly whilst the stretchable material is being stretched to completely go around the item to be secured). Also, repairing cuts and tears in the stretched material, made by adversaries in order to get to the secured item, would likely be hard to conceal, and also of itself, might cause significant security-pattern disturbance (and so increase the level of tamper evidence).

Misc. notes

 * External link to research on home-made tamper-evident security seals for kids and adults alike


text:
Planet Earth/4h. What Makes Wind?

High pressure → low pressure
Wind is fundamentally the flow of air from high pressure to low pressure across the surface of the Earth. Weather reports often discuss barometric readings, indicating regions of the Earth experiencing high or low pressures at any point in time. Air rushes toward low pressures, so regions experiencing low pressure readings on barometers are going to be windier than regions experiencing high atmospheric pressures. These pressure gradients result in much of the weather experienced on the surface of the Earth. Weather reports will often highlight high pressure and low-pressure regions on a weather map to indicate the barometric recordings taken from various weather stations. Lines of equal atmosphere pressure are draw on weather maps to indicate isobars. Isobars are lines of equal atmospheric pressure where there is no change in pressure readings. Theoretically, air masses will typically flow from high pressure to low pressure regions perpendicular to isobars, but are also influenced by the rotation of the Earth’s orbit; Coriolis force. Closely spaced isobars indicate a very high-pressure gradient, and will produce the strongest winds, while widely spaced isobars will produce weaker winds, due to a gentler pressure gradient. Meteorologists map barometric readings from a wide network of weather stations to generate maps of isobars to identify developing strong wind storms.

Geostrophic wind
A geostrophic wind is the theoretical wind resulting from an exact balance between the pressure gradient force and the Coriolis force, called a geostrophic balance. The geostrophic wind is initially directed perpendicular to isobar lines, but with motion also dependent on the Coriolis force, the wind turns resulting in geostrophic wind following directions that are parallel with isobars as they flow toward low air pressure zones. Geostrophic winds occur higher in the troposphere, where friction and changing elevations due to topography and terrain do not interfere with the motion of air in the atmosphere. There are different ways to measure wind direction and wind speed. Weather vanes often mounted to roofs pivot on a rod to indicate prevailing wind direction. Wind direction is expressed in terms of the direction it originates from, so westerly wind, is wind that blows west to east, while northerly wind is wind that blows north to south. Wind socks are also used to indicate wind direction and relative wind speed, since they are more visible from a long distance, they are used at airports and helipads. Weather stations often have an anemometer, which are rotating propellers or cups that can determine wind speed more accurately.

Wind speeds, and the Beaufort Scale
On Earth wind speeds average about 10 miles per hour (16 km/hr), when they are often described as either calm or a gentle breeze. Record high wind speeds on Earth have exceeded 200 miles per hour (322 km/hr), with strong wind storms ranging from 31 miles per hour (50 km/hr) to 73 miles per hour (117 km/hr). Higher wind speeds between 75 miles per hour to values over 200 miles per hour are observed during powerful hurricanes and tornadoes, which cause considerable damage. The Beaufort scale is a scale of wind speeds used by sailors that range from 0 to 17, with values 12 and above indicative of high wind speeds observed in cyclones, and other storms. The scale is 0-Calm, 1-Light air, 2-Light breeze, 3-Gentle breeze, 4-Moderate breeze, 5- Fresh breeze, 6-Strong breeze, 7-Moderate gale, 8-Fresh gale, 9-Strong gale, 10-Whole gale, and 12-Storm, with 12 through 17 indicating cyclone strength winds. Upward winds are a result of heated air masses rising, causing low pressure directly below the rising air. Air moving into this low-pressure space below rising air, results in observed high winds. Likewise, downward winds are a result of cooling air masses sinking, causing high pressure directly below the sinking air. These motions result in convergent and divergent flows, or anticyclones or cyclones. Winds will form a spiral motion due to the Coriolis effect. In the Northern Hemisphere inflowing low-pressure systems (cyclones) will spiral counterclockwise, while outflowing high pressure systems (anticyclones) will spiral clockwise. This is similar to the flow of liquid water in drain experiments conducted in large kiddie pools. Both cyclones and anticyclones can be either large or small, but with low-pressure cyclones wind converges and form large storms that produce significant accumulations of rain and snow. This precipitation results because air rushes upward through the spiraling cyclone cools as it expands crossing the saturation pressure of water vapor, resulting in rain or snow falling. In anticyclones, air will diverge from the center of the high-pressure system which dries the surface of the Earth because the air is undersaturated in respect to water vapor. High pressure anticyclones do not result in rain or snow, but often represent clear and dry weather, and are associated with heat waves during the hot summer.

As low-pressure systems, cyclones, because of their significant accumulations of rain and snows as well as high wind speeds, frequently cause damage. Supercells are cumulonimbus clouds that cause wind to rise within a thunder cloud formation, producing a mesocyclone (a middle-sized cyclone). Frequently these storms will result in tornadoes, whirlwinds, and dust devils, as they move across the landscape. Larger cyclones are given local names depending on where they form. Hurricane is a term used for large cyclones in the North Atlantic Ocean (and sometimes in the Northeast Pacific), while Typhoon is used for large cyclones in the Northwest Pacific Ocean, along the coasts of Asia and Japan. In the Indian Ocean these storms are referred to as simply tropical cyclones.

The Effect of Topography
Topography, such as mountains, valleys and canyons can result in unique interactions between winds and the terrain, resulting in friction and changes in flow. One of the most important effects happens during orographic lifting of air masses over large mountain ranges. This particularly affects the climates, as mountains can restrict the movement of large air masses. Rain shadows result when moist air over ocean basins rises over mountains top. The adiabatic lapse rate results in the air expanding and cooling, with cloud formation and rain as the saturation pressure of water vapor is reached. These slopes of the mountains facing ocean waters can become very wet from the frequent rainstorms and cloud coverage. The Pacific Northwest is particularly lush because of the rain shadow effect, however these air masses as they pass over the mountain range will sink, due to adiabatic lapse rates the air will condense and heat, resulting in undersaturated air in respect to water vapor on the far side. These dry winds result in sides of the mountains that are significantly drier than mountains facing ocean basins. These dry winds are called Chinook “Snow eater” winds in North America or Föhn winds in Europe, which are undersaturated and warmed by their decent from neighboring mountains. These winds melt and evaporate snow from the drier side of mountain slopes.

Wasatch winds occur in Utah, caused by dry westerly winds blowing from the anticyclones or high-pressure zones that develop in the dry Great Basin Desert into narrow canyons along the Wasatch Mountain front. These are more globally referred to as a jet-effect winds, and they can reach high speeds in mountain canyons.

title: Planet Earth/4h. What Makes Wind?