Question

Causes of variation of air pressure

Answer 1

1) Variation with height or vertical variation:
The pressure depends on the density or mass of the air.  The density of air depends on its temperature.  Its composition and force of gravity. I t is observed that the density of air decreases with increase in  height  so the pressure also decreases with increase in height.

2) Horizontal variation of pressure:
The horizontal variation of atmospheric pressure depends on temperature, extent of water vapor, latitude and land and water relationship.

3. Diurnal variation:
At a given station the pressure show the two high and two lows. On normal pressure day two maxima i.e. one at 10 a.m. and another at 10 p.m. and two minimasi.e. one at 4 a.m. and another at 4 p.m. are observed.  Thus there is double oscillation caused by alternate heating and cooling of atmosphere.