What Causes Atmospheric Pressure?

The weight that the atmosphere exerts as it pushes downward causes atmospheric pressure. This pressure in the Earth’s atmosphere affects the weather.

The atmosphere is a thin blanket of gases that surrounds the Earth. The Earth’s atmosphere comprises nitrogen, oxygen and various trace gases. There are four layers in the atmosphere, each of a different temperature: troposphere, stratosphere, mesosphere and thermosphere.

Definition of atmospheric pressure

Atmospheric pressure is the force exerted over the Earth resulting from gravity pulling down on the molecules in the air. The unit of measurement is inches of mercury, or inHg. Atmospheric pressure determines the weather, which occurs in the troposphere. The atmospheric pressure in the troposphere is between 29.92 inHg and 5.92 inHg, according to the University Corporation of Atmospheric Research.

Atmospheric pressure and the weather

High atmospheric pressure exerts a strong force on the air, which causes it to flatten and drop downward. This high pressure results in calm weather and blue skies, as explained by North Carolina State University. Both temperature and moisture affect atmospheric pressure, so if the air in the atmosphere is warm and moist, it is less dense and travels upward. This low-pressure system can result in the formation of clouds followed by rain.