Anonymous
Anonymous asked in Science & MathematicsEarth Sciences & Geology · 2 months ago

# How did air pressure happen?

And how did we all become accustomed to it?

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• Bill-M
Lv 7
2 months ago

Air pressure is caused by Gravity.  How did we become accustomed to it? Evolution.

• Anonymous
2 months ago

Air and other fluids such as water are made of loose freely moving molecules. In contrast, molecules in solid matter do not move around much. Molecules do not move at all in crystals such as diamond and ice. The air molecules move because of heat energy and other forces, such as gravity. The hotter the air molecules, the faster they move. Steam for example, can exert a lot of air pressure because the water vapor molecules are moving at high speed due to high temperature. When air molecules move, they exert pressure on anything that they touch. Birds can stay up in the air because they flap their wings and the air molecules exert more upward pressure on their body than the pressure that is exerted by the air molecules above them. Airplanes do the same. The air pressure under an airplane is greater than the air pressure on top of it because of the shape of its wings. When air moves past the wings, the shape of the wings force the air above the wing to travel a greater distance. That in turn reduces the pressure it can put on the the wing from above. As a result the wing is pushed upward.  Since humans evolved on land, we are used to having air pressure around our bodies at all times. The earth's gravity puts an attractive force on air molecules so they do not escape into outer space. When the air molecules are pulled towards the earth they exert pressure on everything on the surface of the earth.

• 2 months ago

Gravity holds the atmosphere to the Earth. And it holds an atmosphere to any other large enough planet, such as Venus, Saturn, Jupiter etc.

Likewise water or other substances in seas and oceans on planets.

Pressure is proportional to strength of gravity and depth below the "surface". It increases slowly in air, to roughly 1Kg per square centimetre for the full height of the Earth's atmosphere - but rapidly in water, roughly 1Kg per cm^2 per 10m depth, as water is around 830 times denser than air at sea level.

And, life evolved on Earth in the oceans and atmosphere as it was at the time - which was a very different gaseous mix to what it is now.

If the atmospheric pressure was much different, or the gas mix in it was significantly different, "we" - Homo Sapiens with this form - would not be here to discuss the subject.

• 2 months ago

Air pressure is a force, like gravity is a force. We evolved to deal with it. You learn air pressure really does matter when you get altitude sickness and all.you want to do is sleep because not enough oxygen is getting into your blood stream or to your brain. Oxygen deprivation is NOT FUN.

If Earth did not have a GLOBAL magnetic field it would lose most of its atmosphere and surface liquid water quickly because it is closer to the Sun and the solar wind has a higher velocity. Mars lost its global magnetic field slowly in terms of human lifetimes as its mantle cooled and solidified. Mars has about 1/3 of Earth's mass and a proportionally thinner crust and mantle so it cooled quicker than Earth has.