# Why do high altitudes have larger diurnal temperature variation than lower altitudes?

It seems like the lack of atmosphere should not be playing a role in the diurnal temperature variation because that's what makes it colder. Mountains are not that dry, usually.

• It may be better to ask this over at earthscience.stackexchange.com – Isopycnal Oscillation Sep 3 '15 at 5:48
• You have to take radiation cooling and heating into account. The temperature of free space is given by the radiation that's in it, which moves at the speed of light, i.e. without matter a volume of space with dimension $L$ "cools and heats up" on a timescale that is given by $L/c$. Throw matter in there and now you have much slower heating and cooling because the effective speed of light is much, much smaller as photons are absorbed and re-emitted many times before they can escape to the vacuum. – CuriousOne Sep 3 '15 at 13:49