What happens with the temperature when you climb mt Kosciuszko every 100 km?

The air temperature decreases as you climb higher in altitude. On average, the temperature decreases by 6.5°C for every 1000m increase in altitude. This is because the air at higher altitudes is less dense, so it can hold less heat. Additionally, the higher you climb, the closer you get to the tropopause, which is the boundary between the troposphere and the stratosphere. The troposphere is the lowest layer of the atmosphere, and it is where we live. The stratosphere is the layer above the troposphere, and it is where the air is much colder.