Читать книгу Weather For Dummies - John D. Cox - Страница 56

Don’t look now, but waves of energy are radiating all around you. The fact is, everything that has a temperature above absolute zero (–459.67 degrees Fahrenheit/–273 degrees Celsius) is giving off at least some waves of radiation. Your body, for example. Even your Weather For Dummies book. This radiation is an important part of the process of turning the Sun’s energy into weather.

When it comes down from the Sun, however, most of the energy arrives as powerful short-wave radiation, including the spectrum of light that you can see, and this passes right through the atmosphere and strikes the surface of the Earth. Depending on the kind of surface it hits, it bounces back or is absorbed. It all depends on color and surface texture and other properties of the surface. Notice how hot a black asphalt parking lot gets on a summer afternoon, absorbing the heat, and yet, how quickly it cools, or radiates it away, overnight.

People who plan cities and buildings are studying these different heat-absorbing and radiating properties of materials to make downtowns and neighborhoods more energy-efficient and comfortable places to be.

In case you haven’t noticed, the energy that radiates back from the surface travels as long infrared waves, which you and I can’t see. Invisible it might be, but this form of radiation is more important than you might think. The atmosphere, which lets most of the incoming short-wave sunlight pass right through without absorbing it, catches a lot of the rebounding long-wave heat energy and keeps it around. This produces the so-called greenhouse effect that is discussed in detail in Chapter 14.