Why Is It So Cold at the Top of Mountains and Snows?

Gemma in Sydney asks why it's so cold at the top of mountains and snows. The answer is because the air is slightly thinner as well. So basically the air pressure gets lower, the higher up you go. You've also got other effects like wind, but the sun still has a lot of power,. It still has potentially more power because I guess you are slightly closer to it.