On a bright, cool day, most people perceive the sun's rays as feeling good on their skin. By nature, many of us even make an effort to stay out in the sun to bronze our bodies. The sun is 93 million miles away from the Earth and its energy travels to us in moving waves called radiation. That energy takes the form of heat, light, and other energy as well.
Visible sunlight allows us to see the world around us. But there is invisible sunlight as well. These rays can not be seen. Some can be felt as heat, but the ones that can't be felt are called ultraviolet rays. These are the culprits that cause changes to happen to our skin, like wrinkles, tans and even cancer. When a person wears sunscreen, they are protecting themselves from these ultraviolet rays.
A protective blanket of gases, the atmosphere, surrounds our planet. It provides us with the air we breathe, and it protects us from the full blast of the sun's radiation. Way up in the part of the atmosphere, called the stratosphere, a layer of gas filters out most of the sun's damaging ultraviolet rays. This layer of gas is called ozone and is located about five miles to 25 miles above the surface of the Earth. (Bright, 1991).
Only about one-millionth of our atmosphere is made up of ozone. But it has a tremendously important job. Ozonecan absorb, or soak up, the part of sunlight called ultraviolet radiation. Some ultraviolet radiation still gets through, but not enough to do serious damage to Earth. If all of those dangerous rays got through, life as we know it would be impossible.
But there is a significant pending problem in the ozone layer. Each year, a large hole appears in it. It is not an actual hle, but a thinning in the layer that shows up on satellite pictures. The "hole" is located over Antarctica. It covers an area about the size of the United States. Experiments done in Antarctica show that the hole in the ozone layer appears to let in twice as much ultraviolet radiation ans normal, according to measurements researchers made there. Over the whole Earth, the ozone layer has been depleted, or weakened, by an average of about two percent, scientists say. (Fisher, 1990).
Experts are concerned that extra radiation getting through to Earth's surface could lead to problems in the future. During the next century, extra ultraviolet radiation could cause millions of new cases of skin cancer. Scientists say that synthetic chemicals called chlorofluorocarbons are responsible for eating the hole in the ozone lyare. Chlorofluorocarbons, called CFCs, are industrial chemicals used in air conditioners, spray cans, foam food containers, and other things.
Once CFCs get into the atmosphere, they meet up with other chemicals that are already there. During Antarctica's long, dark winter, the lower temperatures in the stratosphere cause ice crystals to form in the air. When the sun reappears in October, it acts on the ice crystals and starts complex chemical reactions between ozone and CFCs. When the chemical reaction happens, the ozone breaks down.
During the 1990's, worldwide use of CFCs was expected to be cut in half. Fifty