Temperature is controlled by the mechanism behind the Ideal Gas Law PV = NRT
P, N and R are constants over time at any particular location in the atmosphere, so the law boils down to two important atmospheric facts:
- Temperature increases with pressure as you descend through the troposphere
- Temperature at any location in the troposphere is proportional to the height of the troposphere above it
The bottom of the Grand Canyon is much warmer than the top, because the atmospheric pressure is higher at the bottom.
The sun shines on the surface of the earth, which in turn emits longwave radiation. This LW radiation is absorbed by greenhouse gases in the troposphere, which maintain their warmth and keep the troposphere from collapsing. Without the energy coming from the sun and the greenhouse gases, the troposphere would shrink and the temperature would be quite cold. During the winter the troposphere does shrink and temperatures go down, because there is less LW radiation being absorbed by greenhouse gases in the troposphere during the winter.
The surface of Venus is very hot because Venus has a tall, high pressure troposphere. It is not hot because of the high CO2 concentration. CO2 absorption saturates even at very low concentrations, so adding more CO2 has very little effect on temperature.
Wikipedia has an article attacking me for stating this most basic and fundamental science – which escapes some of the most famous climate “experts.”
