Why is it colder higher up a mountain?
You can think of it using the ideal gas law: PV = nRT. Pressure x Volume = number of moles x molar gas constant x temperature P is lower, n and R are constants, therefore T is lower. Basically, temperature is a measure of how fast something can transfer heat away from itself. As you go up a mountain, the air gets less dense, ie there’s fewer particles whizzing about and fewer particles can transfer less energy than more particles. There’s another reason to do with the greenhouse effect. We get warmed up by heat coming from the Sun and heat radiated back out by the Earth. Greenhouse gases in the troposphere catch a lot of the heat going out from the Earth (which is mainly in the infrared, so CO2, methane, water vapour etc catch it) whilst gases at the top of the atmosphere catch some of the light coming from the Sun (eg ozone takes out a chunk of the ultraviolet). As you go up the mountain, you’re leaving the region where the most heat is trapped by the greenhouse effect and you’re not
