Write two effects of air pressure

Air exerts pressure in all directions.  The pressure exerted by air is called the air pressure, which is the thrust exerted by air per unit area. 

Factors Affecting Air Pressure:

1. Temperature:  As the temperature increases, air expands because of which its density decreases which results in low pressure. On the other hand air shrinks due to low temperature because of which its density increases which creates high pressure.

2. Height from Sea Level: Air pressure is created due to weight of air therefore sea level has highest air pressure. As we move upward from sea level leaving behind the heavy gases at lower layers of atmosphere, air pressure decreases because the upper air is light and its density is low.

3. Moisture in Air (Humidity): Conversion of water from liquid state to gaseous state because of evaporation is known as atmospheric humidity. Water vapours are light in weight therefore they rise up and pressure of humid air decreases as compared to dry air. Amount of water vapours changes with time and place and because of this the pressure of air also varies.