Why does summer sunshine have more UVB than winter?

The correct choice highlights that the sun's angle in the sky is higher during the summer months compared to winter. This higher angle means that sunlight, including ultraviolet B (UVB) radiation, has a more direct path through the Earth’s atmosphere. As a result, UVB rays are less dispersed and absorbed by the atmosphere, leading to an increase in the amount of UVB radiation that reaches the Earth's surface during summer.

In contrast, during winter, the sun is lower in the sky, which causes sunlight to strike the Earth at a shallower angle. This results in more atmospheric scattering and absorption of the UVB rays before they reach the surface, thus decreasing the levels of UVB radiation available in winter.

Understanding this concept is crucial for recognizing how environmental factors influence UV exposure, which is important for making informed choices about tanning and skin protection year-round.