Why does the troposphere have the greatest air pressure

The more air above a level and hence the more weight of air above a level , the greater the squeezing effect or compression. Since air density is the number of air molecules in a given space volume , air density is typically greatest at the surface or sea level where it is squeezed by the weight of the entire atmosphere above and decreases as we move up in the atmosphere because the weight of air above becomes less and hence there is less of a squeezing effect See Figure Z.

Atmospheric air pressure results from the Earth's gravitational pull on the overlying air. Without gravity holding the atmosphere just above the ground surface, air molecules would spread out, and the gas pressure would be close to zero.

The weight of the atmosphere acts as a force upon the underlying surface of the Earth. The amount of force excerted over an area of surface is called atmospheric pressure or air pressure. Near sea level, the average air pressure is about In this class we will use the unit millibars mb to specify air pressure.

At sea level the average air pressure is mb. Another way to think of this is that the total weight of all the air above sea levels weighs enough to cause mb of air pressure.

Since the air a gas is a fluid, the pressure force acts in all directions, not just downward. Related questions How does atmospheric pressure affect evaporation? How do you calculate atmospheric pressure at an altitude?

What causes hydrostatic pressure in blood vessels? How is hydrostatic pressure created? How does atmospheric pressure change in the troposphere? Sea level is the mean boundary level between the sea and the atmosphere. At this point the sea level pressure the weight the atmosphere puts on any point on Earth that has the level the sea does is mb.

Lessons and Modules Introduction to Clouds Atmospheric Pressure The Earth's atmosphere is divided into four layers that begin at sea level and extend to a height of about km miles. Red columns indicate atmospheric pressure. That's why the cabins of high-flying jet aircraft are pressurized. The layer immediately above the troposphere is called the stratosphere. The boundary between the troposphere and the stratosphere is called the "tropopause".

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