Answer:
Earth's surface receives different amounts of solar radiation because it is curved.
Explanation:
Earth, like all planets, is curved, or rather it has a round shape. More specifically, Earth has a generalized elliptic shape, though if we go into detail then it is a geoide. Such a shape means that not all parts of the planet can get the same amounts of solar radiation because of the different angles at which the sunlight falls on the surface.
The areas that are located around the equator are the ones that receive solar radiation at direct or close to direct angle throughout all of the year. This is results in a large concentration of the rays and the surface hits up. On the other hand, around the poles, the solar radiation that is received comes at very low angles. This results in a wide dispersal of the rays so the surface doesn't heat up enough and that is why the temperatures are always low.