How did the earth's atmosphere evolve?

Answer 1

The center of the earth is hot due to radioactive decay of long lived isotopes such as Uranium 235 and Potassium 40, and the insulating effect of all the iron and rock over-top of it. It gets so hot in fact that the iron down there melts and starts to rise, this sets up convection currents that form get cycling cells kind of like (only slightly so) bubbles in a boiling pot of water. These cycling cells of hot iron are what produce the earth's magnetic field.

These moving current of magma tend to push the surface rock around in slowly moving plates, these plates of moving rock are what the continents are on and therefore we have continental drift. The upwelling magma at the mid-Atlantic ridge and elsewhere produce chains of under=water volcanos that bring fresh elements to the ocean water that support life.

The leading edge of the moving continents buckle up and produce mountains on the land. These get eroded by weather and return nutrients to the sea.

Answer 2

A brief answer: early Earth's atmosphere was much more dense and in different composition than current one; the most important difference was the lack of oxygen and much less nitrogen - all of the oxygen and most of the nitrogen were produced after the emerging of life. As the primordial gases got blown by the solar radiation, the early Earth's atmosphere lost the major portion of its mass, but frequently got replenished by new gases and vapors from the volcanic eruptions.

Let a geologist post a long detailed answer.

Meteorites that hit the earth in its early stages produced nitrogen, making it the most available gas in the world. Nitrogen now makes up most of our air.

Answer 3

The Earth did not evolve. The things ON it did.

Answer 4

people did not evolve