The atmospheric pressure:
With the name of atmospheric pressure in a point, we designated the “weight” of the air column that is over that point (until the atmosphere finishes). This value as it is possible to be understood is very difficult to make specific because the density of the air falls with the height (affecting therefore to the mass and consequently to the weight), in addition to varying with the meteorological conditionses.
A measurement of the atmospheric pressure “standardized” in some “Stable” conditions and to an equal height to the sea level settled down therefore. One settled down that the measurement of standard atmospheric pressure in these 101325 conditions was of Pascales (Pa) that are equivalent to 1 atmosphere or 1013.25 millibars.
In this Web you will find measures of measured atmospheric pressure in surface, that is to say, is affected by the height and thus we see as in a period with stable conditions, a weather station that is to more height than another one registers values of pressure smaller than the one than is to smaller height.
It is the instrument of which we used to realise the measurement of the atmospheric pressure. There are barometers of different types.
Torricelli inventói the mercury barometer in 1643 that consisted of one columnade mercury of 860 mm closed on the other hand superio and opened by the inferior but within a Cuba of the same liquid. Mercury of Cuba is exhibited to the atmospheric pressure that resists to the weight of the mercury column that will raise or lower based on the value of this pressure.
Perhaps another variant of barometer and on that they have been implemented variant conforms has advanced the technology is the “Aneroid Barometer” that it consists of a capsule closed with flexible walls in whose interior the emptiness has been realised. The variation of the atmospheric pressure when exposing this capsule to the same cause that the walls inwards flexionen in major or measured minor. The measurement of this flexion or movement of the walls of this capsule, offers a possibility to us of measuring the pressure. From this type of barometer they are possible to be implemented infinity of systems and materials that facilitate the measurement of that flexion of the walls of the capsule.