Name: Weather and Climate
Uploaded: 2019-07-19
Duration: 5 min 54 s
Description: Have you ever used the words weather and climate interchangeably? But is it the same? Watch this video to find out.

Question

What is meant by atmospheric pressure? Which factor determines the horizontal distribution of pressure?

Accepted Answer

Force exerted by the weight of air on the Earth's surface is called atmospheric pressure. Air has weight, so it exerts a force, i.e., pressure on the Earth's surface. On the moon, there is no air and hence no air pressure. The air is dense near the surface at sea level, and hence pressure is highest here. As the air thins out with an increase of altitude, pressure decreases with height.

Horizontally, the distribution of air pressure is influenced by the temperature of the air at a given place. In areas of high temperature, when the air warms up, it becomes lighter due to expansion. The warm air weighs less than cool air, which means that warm air presses down on the Earth's surface lesser than cool air. It creates low pressure.

When the temperature is low, cooling of the air contracts it, and makes it heavier. The heavy air sinks toward the Earth, exerting more force. This increased force creates high pressure. As the air descends, no clouds are formed. So, clear skies and fair weather are characteristic of high-pressure areas.

What is meant by atmospheric pressure? Which factor determines the horizontal distribution of pressure?

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