Greenhouse Effect .
On a bright, cool day, most people notice the sun's rays as feeling good on.
their skin. By nature, many of us even try to stay on the sunny side of the street.
while walking. The sun is 93 million miles away from earth and its energy travels.
to us in moving waves called radiation. The energy becomes heat, light and other.
energy too.
Visible sunlight allows us to see the world around us, but there is invisible.
sunlight, too. These rays can't be seen, but some can be felt as heat. They are.
called ultraviolet rays, and they are what changes the appearance of the skin, like.
wrinkles and even cancer. .
I discovered a blanket of gases known as the atmosphere surrounding our.
planet. It is what provides us with the air we breathe, and it protects us from the.
full blast of the sun's radiation. Way up there in the part of the atmosphere called.
the stratosphere, a layer of gas called ozone, filters out most of the sun's damaging.
ultraviolet rays. This happens about five miles to 25 miles above the surface of.
Earth (Bright 14-15). .
Only about one- millionth of our atmosphere is made up of ozone. But it.
has an important job. Ozone can absorb the part of the sunlight called ultraviolet radiation. Some ultraviolet radiation still gets through, but not enough to do.
serious damage to Earth. Because if it got through, life as we know it would be.
impossible. .
But there is a serious problem in the ozone layer. Each year, a large hole.
appears in it. It isn't an actual hole, like a hole in a pocket, but a layer getting.
thinner as it shows up on the satellite pictures. The "hole" is right over Antarctica,.
covering an area about the size of the United States. Experiments done in.
Antartica show that the hole in the ozone layer appears to let in twice as much.
ultraviolet radiation as normal, according to measurements researchers made there.
