What is the definition of ozon layer?

Answer 1

Brief answer:

The ozone layer is a thin layer of ozone that protects the earth from dangerous ultraviolet light. When the layer is thin or damaged this ultraviolet radiation can cause eye cataracts, skin cancers and damage to crops.

More detail:

The ozone layer is a region high in the stratosphere, containing ozone (a form of oxygen) that filters out most of the Sun's dangerous ultraviolet rays (UV-B). This UV-B could otherwise be absorbed by the DNA in all surface dwelling life on Earth. Ultraviolet radiation can cause cataracts, cancer, and mutation. It can also reduce crop yields, and damage arable land.

The ozone is located between 4 and 10 miles above the surface of the Earth (lower near the poles), with the highest ozone concentrations in a region that is variously called the lower stratosphere, the tropopause, or simply the "ozone layer".

Ozone itself is a triatomic molecule, composed of three oxygen atoms that bonded, unlike the oxygen we breathe, which are diatomic molecules, meaning two oxygen atoms. The "ozone layer" contains more than 90% of the earth's ozone. Ozone is a corrosive, light blue gas with a smell something like burning electrical wiring. The atmosphere at this altitude is still about 78% nitrogen, 21% oxygen, and the peak ozone concentration is about 9 ppm (or 0.0009%). Other things (water vapor, carbon dioxide, argon, and so on) are present there in small concentrations too.

The ozone layer has been depleted during the 20th century by chlorofluorocarbons (CFCs) and halogens. When the damage to the ozone layer became clear during the 1970s the Montreal Protocol, an international treaty to limit their production was set up, and came into force in 1989. Despite this phasing out, ozone levels in the stratosphere are still low and scientists predict they will not recover until 2050.

An ozone hole also periodically forms, since ozone is unstable. The word "hole" is somewhat misleading. This is actually a diminished concentration of ozone due to the lack of sunlight and not a complete absence. An ozone hole forms over a pole, then later closes, once each year at the pole that is not receiving UV-C light from the Sun. The southern polar hole is larger than the northern polar hole, due to the polarity of Earth's magnetic field. Chlorofluorocarbons (CFCs) make the hole larger, last longer, and contain less ozone, which is only an indication of the general "health" of the ozone layer. The hole itself forms in areas that are receiving no UV-B from the Sun either, so there are no lifeforms at risk from our Sun directly "beneath the hole," but every surface organism is at risk from a thinned ozone layer.

If you took all the ozone in an entire column from the ground to infinity, and compressed it to STP (standard temperature and pressure, or 0°C at 1 atmosphere pressure) it would be a layer about 3 mm thick. There is less than 1/3 as much in the Antarctic "ozone hole" when it is winter there.

Answer 2

Ozone layer is a layer in atmosphere. It protects us from the harmful UV rays of the sun.

Answer 3

The ozone layer is pool of ozone molecules. They are present in the atmosphere.