Air Pressure

You will be surprised to know that air above us presses us with a great force on our bodies. However, we don't even feel it.

This is because the air presses us from all directions and our body exerts a counter pressure.

    Air pressure is defined as the pressure exerted by the weight of air on the earth's surface .As we go up the layers of atmosphere, the pressure falls rapidly. The air pressure is highest at sea leval and decreases with height. 

Horizontally the distribution of air pressure is influenced by temperature of air at a given place.In areas where temperature is high the air gets heated and rises. This creates a low - pressure area. Low pressure is associated with cloudy skies and wet weather.

In areas having lower temperature, the air is cold.It is therefore heavy air sinks and creates a high pressure area.

High pressure is associated with clear and sunny skies.

The air always moves from high pressure areas to low pressure areas.

On the moon there is no air and hence no air pressure.

Astronauts have to wear special protective space suits filled with air when they go to the moon.If they did not wear these space suits,the counter pressure exerted by the body of the astronauts would make the blood vessels burst.The astronauts would bleed.