Why is it warmer at the equator than in the temperate zones?

This is quite easily explainable physical effect. The main source of heat on Earth is solar radiation. At the equator, the sun’s rays fall at right angles, i.e. perpendicular, which means that the area on which each ray falls is minimal. This means that each part of this surface will be heated more, because it will have a high average temperature that a sunbeam can transmit to the earth. The opposite situation is in the temperate zones, in which the sun’s rays fall obliquely, which means that the area of ​​influence is smaller and heating is not so active.