The Stratospheric Ozone Layer

• UVA. This group of UV radiation with wavelengths from 320-400 nm produced by the sun and is not absorbed by ozone. This range of wavelengths just shorter than visible violet light.
• UVB. This group of UV radiation with wavelengths from 280-320 nm produced in the sun. UVB is some kind, ultraviolet rays from the sun (sun), which has a number of harmful consequences, particularly effectively to DNA damage. This is the cause melanoma and other skin cancers. This also relates to damage to some materials, crops and marine organisms. The ozone layer protects the earth from most of the UVB rays coming from the sun. It is always important to protect yourself against UVB, even in the absence of the ozone layer by wearing hats, sunglasses, and sunscreen. However, these measures will become more important as ozone depletion worsens. UVC. This group UV radiation wavelength less than 280 nm. Although extremely dangerous, it is fully absorbed by ozone and normal oxygen (O2).

The troposphere is the region of the atmosphere closest to the earth and extends from the surface to 10 km in height, although the height depends on the latitude. Almost all weather occurs in the troposphere. Everest-the highest mountain on earth, is only 8.8 km temperatures decrease with height in the troposphere. As warm air rises, it cools, falling back to earth. This process, known as convection, means that there are huge flows of air, which combine in the troposphere very effectively.

Ozone is a gas composed of three atoms of oxygen, as is known bluish gas, which is harmful to breathe. Almost 90% of the earth's ozone resides in the stratosphere, and is called the ozone layer. Ozone absorbs a group of UVB that is particularly harmful to living organisms. The ozone layer prevents the majority of the UVB rays reach the earth's surface.

The ozone layer is a region of the stratosphere containing major part of the atmospheric ozone. The ozone layer is approximately 15-40 km above the earth's surface in the stratosphere. The ozone layer is located between 2 and 5 mm thick in the stratosphere at normal temperature and pressure, and its concentration varies depending on the season, time of day and location. The concentration is greatest at an altitude of about 25 km near the equator and at the height of 16 km near the poles. The ozone comes mostly from photodisassociation oxygen UV radiation of very short wavelength (i.e., 200 m).

Column ozone ozone between earth's surface and space. Levels of ozone can be described in several ways. One of the most common measures the amount of ozone in a vertical column of air. In Dobson units (DU) is a measure of the destruction of the ozone layer, which is described in the following paragraph. Other measures include partial pressure, density, concentration of ozone, and can represent either the destruction of the ozone layer, or the amount of ozone at a certain height.

Unit Dobson (DU) is a measure of column ozone levels. If 100 DU ozone were brought to the surface of the earth, it would form a layer thickness of 1 mm In the tropics, the levels of ozone usually between 250 and 300 DU year round. In temperate regions, seasonal variations can produce large variations in the levels of ozone. For example, measurements in St. Petersburg recorded ozone levels as high as 475 DU and as low as 300 DU (Wayne, 1991). These changes occur even in the absence of the ozone layer. Depletion of the ozone layer means the reduction of ozone is below the normal level after accounting for seasonal cycles and other natural effects. DU is convenient to measure total ozone, occupying a column overhead. If the ozone layer over the United States have been condensed 0 C and 1 ATM pressure, it would be about 3 mm thick. So, 0.01 mm thick 0 C and 1 ATM defined as 1 DU; it makes the ozone layer above the measures of the United States, about 300 DU. In absolute terms, 1 DU about 2.7 x 1016 mol/cm2 (Wayne, 1991). In total, there are about 3 billion tons, or 3 x 1015 g, ozone in the earth's atmosphere; about 90% in the stratosphere. In absolute terms, ozone is distributed 1012 mole/cm3 at 15 km, rising to almost 1013 25 km, then falls to 1011 45 km, and in relative terms, ozone covers approximately 0.5 parts per million by volume (ppmv) 15 km, an increase of about 8 ppmv, about 35 km) and drop up to 3 ppmv 45 km (Wayne, 1991).

In the past, ozone measurements were made from the earth using a precisely calibrated Dobson instrument and, more recently, other types. Fluctuations of concentration was very large, depending on the season and the seasonal activities of the weather due to changes in solar activity, some of which were obviously stochastic nature, that the cause of yet unexplained...