Why is there air? - How does it stay near the surface of the earth?

Answer 1

Air stays near the surface of earth because air has mass too. So its Earths gravity that keeps air near the surface. As for the question why does earth have air, do you mean how did air form on earth? First of all air consits 78% nitrogen 21% oxygen and 1% nobel gases (helium, neon, argon, krypton, and xenon) and less then 1% of it being carbon dioxide, water vapor, and miscilanious crap. The origin of earths atmosphere is not fully understood but it is believed oxygen entered the atmosphere through the action of prehistoric cyanobacteria that broke down carbon dioxide through processes similer to photosynthasis. http://en.wikipedia.org/wiki/Air. As for nitrogen and nobel gases came as a by product of the nuclear reaction of our sun during our planets formation.

Answer 2

There is air because it has mass. The denser something is the lower it will go. Earth's gravity causes the gases to stay in the sky. The sky looks vast, but it is very thin compared to the mass of the earth. Kind of like the thickness of paper on a 12'' globe. Since our moon is so small it cannot hold an atmosphere. That is why it is a big shiny rock in the sky.
Venus looks pretty when viewed from a telescope, but it is not a good vacation spot. The poisonous gases are under a lot of pressure and have trapped a lot of heat from the sun, making it hotter than Mercury.

Answer 3

Earths original atmosphere was probably lost to space due to the T-Tauri wind: intense solar wind created when the sun ignited. A second atmosphere was created probably by a combination of volcanic outgassing and meteor impact. Early life was able to break down the original carbon dioxide-rich atmosphere, producing oxygen. When the oxygen content of the atmosphere grew large enough, it basically killed almost all of the existing life on earth. Some lifeforms were able to utilize this destructive gas and life on earth took off in new directions. And like what every one else has mentioned, it stays put due to gravity. If the earth was less massive like Mars, the suns energy would cause the atmosphere to bleed into space. If we were a bit more massive the atmosphere would be thicker, the temperatures hotter, and thanks to the greenhouse effect we would resemble the hell planet venus.

Answer 4

I am going to address the one point no other answerer mentioned. The reason the Earth has air is because of the Earth's magnetic field. On smaller bodies, such as Mars or the moon, that do not have magnetic fields, electro-magnetic radiation from the sun strips away the atmosphere. The heavy sulfur dioxide atmosphere of Venus (which I believe lacks a magnetic field) is probably due to large amounts of sulfur reacting to oxygen on the surface of the planet.

Answer 5

Bill Cosby answered the first question in one his early comedy albums.

Air stays near the surface due to GRAVITY.

There is air because certain chemical compounds produced by the earth, its seas, plants & animals are gases. These gases form air.

Answer 6

There are forms of matter like solid, liquid and gaseous. Air is gaseous. Air is attracted to to the earth through gravity.

The moon has 1/6 the gravitational pull of the earth and it also doesn't have any air.

Answer 7

The gases in our atmosphere are produced by chemical reactions on Earth. Gravity holds these gases close to Eart, creating our atmosphere.