18B Special Zones in the Atmosphere
There are a few zones in the atmosphere that are pretty special. They do some very important things for the earth and help improve our ability to put dominion into practice. Their presence suggests that God designed them as features of a very good earth. Let's take a look at them.
18.6 Ozone Layer We started this chapter mentioning smog in large cities around the world. A lot of this smog contains a gas called ozone. It's actually a kind of oxygen, but you couldn't breathe it for long. Ozone in small amounts causes lung irritation and breathing problems. In high concentrations, it can kill. But did you know that high up in the stratosphere there is a layer of ozone? There, it actually helps life! This region is called the ozone layer. It extends from about 20 km (12 mi) to 50 km (31 mi) above the earth's surface but it is densest in the middle of this band. An ozone molecule (0,) has three atoms of oxygen bonded together.
This is different from an ordinary oxygen molecule, which has just two atoms of oxygen (02). When an ordinary oxygen molecule in the stratosphere absorbs high-energy ultraviolet light from the sun, it breaks apart. Each of these lone atoms immediately joins another oxygen molecule to form ozone. Ozone is even more efficient than oxygen molecules at absorbing ultraviolet energy. Certain kinds of ultraviolet radiation are quite dangerous to life. They can kill single-celled organisms, and can cause cancers and other abnormalities in most animals and humans. The ozone layer is vital for living things because it shields them from much of the sun's harmful ultraviolet light. It converts this energy to heat. This is why the stratosphere is warmer than the troposphere below it (see Figure 18-10 on page 432).
When space probes began examining the earth's atmosphere in the early stages of the space program, they discovered a broad hole in the ozone layer over the South Pole. Scientists became concerned, as it seemed to be growing wider. Further research showed that the ozone layer over the rest of the world was thinning too. This could become a problem for all life on Earth. Read the facet on the next page to find out more about the ozone hole and our efforts to correct this problem.