Desert: A desert is an arid region characterized by extremely high or low temperatures, low rainfall and scarce vegetation. Water supports life, giving our earth the name ‘living planet’. It is very difficult to live in a place where there is no water to drink, no grass to feed the cattle and no water for the growth of grass. Hence the need to conserve water cannot be overemphasized.
It is a wonder that people who live in the deserts have learnt to have cope up with extremely harsh climates. Desert is either as hot as fire or as cold as ice.
Hence, depending on the temperature, we can find hot deserts or cold deserts. People inhabit these lands wherever little water is available to practice agriculture.
The Sahara desert covers a large part of North Africa. It has the following features:
The climate of the Sahara desert is scorching hot and parch dry. It has a short rainy season. Since the sky is cloudless and clear, the rate of water evaporation is greater than the rate of water accumulation. Hence there is water scarcity. The temperatures are as high as 50C. This heats up the sand and the bare rocks; which in turn heat up their surroundings. The nights may be freezing cold with temperatures nearing zero degrees Celsius.
Flora: Vegetation in the Sahara desert includes cactus, date palms and acacia. We can find oasis in some places.
Fauna: The animal species found here are camels, hyenas, jackals, foxes, scorpions and many varieties of snakes and lizards.
The Sahara desert has been inhabited by different groups of people who are engaged in different activities. Among them are the Bedouins and the Tuaregs. These groups are nomadic tribes. They wear heavy robes to protect them from the harsh climate i.e. dust storms and hot winds.
The tribes are engaged in animal rearing. Animals such as sheep, goats, camels and horses are reared for the following purposes:
Growing date palms and agriculture: The oasis in the Sahara and Nile valley in Egypt supports settled population. Since water is available, people grow date palms. Other crops that are grown include rice, wheat barley and beans. Egyptian cotton that is famous worldwide is grown in Egypt.
Oasis: In the depressions (which are formed when the wind blows away the sands) where underground water reaches the surface; oasis is formed. These areas are fertile. People may settle around these water bodies. People may grow date palms and other crops. Sometimes the oasis may be abnormally large.
The discovery of oil is constantly transforming the Sahara desert. The discovery of oil has been made in Algeria, Libya and Egypt. Other important minerals found in this area include iron, phosphorus, manganese and uranium.
The changes due to business development and infrastructural development are also seen in this area.
Under a baking sun, a weary traveller trudges across a seemingly never-ending expanse of desert. Looking up, he suddenly spots something in the distance: a sparkling lake. He rubs his eyes. It’s still there. Picking up the pace in glee he strides ahead… only for the water to melt into thin air.
You might think our traveller was hallucinating, but mirages are a naturally-occurring optical illusion. In cartoons, a mirage is often depicted as a peaceful, lush oasis lying in the shade of swaying palm trees, but in reality it is much more likely to look like a pool of water. The illusion results from the way in which light is refracted (bent) through air at different temperatures. Cold air is denser than warm air, and therefore has a greater refractive index. This means that as light passes down from cool to hot air, it gets bent upwards towards the denser air and away from the ground. To your eyes, these distorted rays seem to be coming from the ground, so you perceive a refracted image of the sky on the ground. This looks just like a reflection on the surface of a pool of water, which can easily cause confusion.
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