Glenn Dedrick, age 13, of Charlotte, N.C., for his question:
HOW THICK IS THE OZONE LAYER?
Recently we heard reports that man made pollutants may cause changes in the ozone layer. Changes in this region of the upper atmosphere might be disastrous to all plants and animals on the earth. For the slim ozone layer aloft acts as a planetary umbrella to shield us from deadly ultraviolet radiation that reaches the upper atmosphere from the sun.
A vertical diagram of the earth's atmosphere, from the surface to the top, looks as simple as ABC. The different layers of air are shown as neat bands, separated by level lines. But diagrams are intended to be simplified pictures. In this case, the simplification tends to be overdone. The airy layers above our heads may be higher above the equator than they are above the poles. They also tend to merge into each other, and possibly the hazy boundaries between them change from time to time and place to place.
For these reasons, we cannot be very precise about the exact depth of the ozone layer. All we can say is that it begins at more or less 12 miles above the surface, most likely somewhat lower over the polar regions and higher above the equator. From this hazy beginning it extends upward to perhaps 17 miles above the planet. Hence its approximate depth is about five miles.
The weathery troposphere extends from the surface to a height of from about five to 10 miles. Above this is the stratosphere, favorite realm of the highflying jets. Within the stratosphere are regions where certain gases are more concentrated. One is the thin sulphate layer, and above it is the ozone layer.
The ozone molecule contains three atoms of oxygen. The third atom is loosely attached and prone to break away to combine with other substances. Hence, ozone is rated as a chemically active gas. This enables it to react with ultraviolet radiation, which reaches the upper atmosphere with other higher power solar energies.
Ultraviolet rays penetrate soft tissues with no trouble at all, where they are fatal to the living cells of plants and animals. That slim ozone layer way above our heads has an enormous responsibility. Without its protective umbrella, all life on earth would perish. Hence, certainly we do not want anything to happen to it.