What has the greatest impact on the temperature of the earths atmosphere?

Answer 1

carbon dioxide contributes to a greenhouse effect.

The sun has the greatest impact on the earths atmosphere. The sun heats the air, the oceans and the ground. The oceans and the ground store the heat and release it into the air even at night when the sun isn't around.

The heat of the sun makes ocean water evaporate. The water vapor condenses into clouds which eventually results in rain which water our crops, make plants grow gibing us food and feeding animals which also feeds us (if you eat animal parts).

The heat of the sun warms air in the warmer regions nearer to the equator. The warm air rises. At the polar regions (north and south) the colder air descendsa and moves south to replace the rising warm air which heads to the poles to replace the cold air descending. The air reaching the equatorial regions warms up and rises. The warm air reaching the poles gets colder and descends.

That combined with the rotation of the earth results in wind carrying clouds from over the ocean to the land areas where we need the rain.

There a 1958 video describing this with nice animation. It is extremely informative although a bit dated as much science work in those days was done manually since there were no computers available to automate the process. It is called "The Unchained Goddess". (It has nothing to do with religion). It is available at YouTube. I Haven't been able to put a link to it here but you can search for it there.

Answer 2

The green house effect has the greatest impact on the temperature of the earth atmosphere. Accumulation of carbon-dioxide and some other gases is responsible to a greater extent for rise in the temperature.