Читать книгу Weather For Dummies - John D. Cox - Страница 62

The closer together the rays of sunshine, the more intense the energy. This idea helps explain why the energy from the Sun is weaker when it shines on the polar regions of Earth than at the Equator. These regions remain cold even though the Arctic and Antarctica, at the North and South Poles, get many hours of daily sunshine during the summers in the Northern and Southern Hemispheres. It has to do with the angle at which the sunlight strikes.

Try this at home. Notice how much brighter a flashlight’s beam is when it is shining directly at a surface and how quickly it fades when you spread the beam out at a greater angle and over a bigger area.

Everybody notices this effect of the sunshine between the different seasons, of course. Unless they live in the Tropics, the region of the world along the Equator, where the Sun is more or less directly overhead all year long. For most of the world, the winter Sun that comes glancing in at a low angle is a pretty weak sister to the summer Sun that spends a lot of time directly overhead. Figure 3-7 illustrates the point. The next section of this chapter explains the cause of this seasonal angle.