Читать книгу Weather For Dummies - John D. Cox - Страница 54

The atmosphere is always in the process of converting the Sun’s energy from one form to another and moving it from place to place. Behind all the motion, and commotion, is a complicated exchange of energy between the atmosphere and the Earth. Things are out of balance, and the system is trying to even them out. Weather is the name we give to the atmosphere’s turbulent efforts to balance the cold with the hot, the dry with the wet. The atmosphere deflects more of the Sun’s radiation than it absorbs, and Earth’s surface has a solar energy surplus. This exchange process is what keeps the atmosphere from becoming unbearably cold and the ground you and I stand on from getting unbearably hot.

Through heat-transfer processes that weather scientists call conduction and convection, the radiation surplus is continually moving from the surface up into the atmosphere. The heat is conducted directly from the surface to the thin layer of atmosphere above it. You might say that the convection process takes it from there, mixing it through winds and other weather processes among the higher layers of atmosphere.

While weather watchers like you and I focus on the sky, on the rays of the Sun beating down on us and on the rain or snow falling from the clouds, a weather scientist sees things as part of an energy transfer that is moving from the ground up. A winter storm at the seam between two air masses, which this chapter’s previous section, “News from the Fronts,” is about and Chapter 8 describes more fully, is transferring energy from the surface to the atmosphere. So is a summer thunderstorm, which Chapter 10 describes. And so is an autumn hurricane, which Chapter 7 details. Through conduction and convection, they are all moving one form of heat or another from a warmer region to a cooler one.

Later in this chapter, the section, “The Big Picture” explains why the atmosphere never succeeds at this process of balancing the Sun’s energy around the world. Figure 3-4 shows what happens to the radiation from the Sun striking Earth.

FIGURE 3-4: Here’s what happens to the radiation from the Sun once it reaches the atmosphere.