on earth, we have the poles being very cold and mostly frozen, while the equator is very warm and humid. i would like to know specifically what causes this. i know it is partially because of their exposure to the sun, but i'd like to know some of the details and factors involved. i'd also like to know if the process could be reversed, as in the poles would be warm or at least moderate temperature, while the equator of the planet was frozen? if so, how and why?