Here's why:

* Angle of Incidence: Solar radiation hits the Earth at a more oblique angle at the poles compared to the equator. This means the same amount of energy is spread over a larger area, resulting in less intense radiation.

* Longer Path through Atmosphere: Sunlight has to travel through more of the Earth's atmosphere at higher latitudes. This increases the chance of scattering and absorption, further reducing the intensity of the radiation reaching the surface.

* Polar Night: During the winter solstice, the poles experience 24 hours of darkness, receiving no direct sunlight at all.

In contrast, the equator (0 degrees latitude) receives the most direct radiation because the sun's rays hit it at a near-perpendicular angle.