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ATMOSPHERE
Lesson 2 - Page 1

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AIR PRESSURE

Air has weight and exerts pressure when contained. Air weighs more than five quadrillion tons, but yet we can't see, smell, or feel it. Air is a powerful force on Earth exerting pressure on all organisms. Even when you take a breath of air into your lungs, you are changing the pressure. When you blow in air, you increase the molecules of gas; when you blow, you decrease the pressure. The pressure inside your body actually prevents the atmospheric pressure from squishing you. However, if we visited Jupiter, the surface pressure would squish us like a bug.

Astronauts that go into space or divers that go under the ocean must take pressurized air with them. If we climb a mountain that is too high, the air becomes less and less breathable. The downward force exerted by overlying air causes greater pressure at the bottom of the atmosphere. Air molecules are actually "squeezed" by the weight of the air above. The pressure is measured as101,325 Pascals which is called 1 atmosphere of pressure on the surface of the Earth. We can live at 1 atmosphere, but once it gets below (outer space) or higher (under the ocean) we have to create pressurized cabins to keep our pressure at 1 atmosphere, so we donít "pop."


Divers use pressurized tanks to breathe
  


Astronauts required pressurized air 
for their entire body

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