Why is the temperature between different layers of atmosphere constant?
It has to do with the way solar radiations interfere with the air molecules. In the exosphere, there isn’t enough air molecules to really differentiate from vacuum. But in the thermosphere, UV radiation polarize molecules. This is the largest part of our atmosphere. Under that, in the mesosphere, the temperature sinks with altitude but not in the stratosphere, where the air is so thin that it lays in layers, the warmer one above because warmer air is lighter. In the troposphere, where we live, the temperature sinks with altitude, of course. One could think that warm air rises and stay there, as in the stratosphere but here, the adiabatic cooling of a lesser pressure aloft cools it down. The troposhere is higher at the equator than the pole. That is simply because, at equal pressure, a column of wamer air is lighter than one of cold air. But there is also another reason; the tropopause, or the top of the troposphere is much colder over equator than the poles.
