Why are the earth’s polar regions cooler than the earth’s tropical (equatorial) regions? They receive less radiation from the sun, due to their orientation relative to incoming sunlight.
They are farther away from the sun, so they don’t heat up as much.
They are cooled by the polar ice caps.
Winds tend to be stronger near the poles, leading to a cooling effect.

They receive less radiation from the sun, due to their orientation relative to incoming sunlight.

Explanation:

Earth has multiple different climate zones, roughly arranged by latitude. The difference in climates comes because of multiple factors, but the most important one is the Sun and the sunlight of it. Because Earth has a rounded shape, different parts of it receive different amounts of sunlight.

If we compare the tropical and polar regions as two contrasting regions, we can see huge differences. The tropical regions are warm or hot all year round, while the polar regions are very cold throughout all of the year. The tropical regions though receive sunlight at a much more direct angle, thus the sunlight is much more concentrated and heats up the region. The polar regions receive sunlight at a very low angle, so they are dispersing over a very wide area so they can not warm up the region.