Many gases are found in the atmoshere but it can be considered to be composed of mainly nitrogen and oxygen. An estimate of the composition of the atmosphere is given in the following table:. Other rare gases are hydrogen, helium and ozone. Besides water vapour, dust particles, smoke, salts and other impurities are also present in the air, in varying quantities. The bottom of the stratosphere is around 10 km 6. The top of the stratosphere occurs at an altitude of 50 km 31 miles.
The height of the bottom of the stratosphere varies with latitude and with the seasons. The lower boundary of the stratosphere can be as high as 20 km 12 miles or 65, feet near the equator and as low as 7 km 4 miles or 23, feet at the poles in winter. The lower boundary of the stratosphere is called the tropopause; the upper boundary is called the stratopause. Ozone, an unusual type of oxygen molecule that is relatively abundant in the stratosphere, heats this layer as it absorbs energy from incoming ultraviolet radiation from the Sun.
Temperatures rise as one moves upward through the stratosphere. This is exactly the opposite of the behavior in the troposphere in which we live, where temperatures drop with increasing altitude. Because of this temperature stratification, there is little convection and mixing in the stratosphere, so the layers of air there are quite stable.
Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below.
The stratosphere is very dry; air there contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere. Tropospheric ozone is an ozone gas that occurs in the troposphere in trace amounts. The average concentration of ozone in the troposphere is ppb when considering the volume. However, the polluted area of the atmosphere contains about ppb. The ozone layer exists between 10 to 50 kilometres above Earth, in the atmosphere where the stratosphere occurs.
Therefore, we can find the least amount of ozone in this area. When considering the creation of the tropospheric ozone, it is formed from the chemical reaction between oxides of nitrogen and volatile organic compounds at the ground layer of the atmosphere.
This reaction takes place in the presence of sunlight to form ozone gas. The concentration of ozone gas increases as the height above sea level increases. The maximum concentration occurs at the tropopause. It is the boundary between the stratosphere and troposphere. Although the ozone layer is very important to us, the ozone gas in the troposphere is considered a greenhouse gas that can contribute to global warming. The key difference between stratospheric ozone and tropospheric ozone is that stratospheric ozone concentration is very high, whereas tropospheric ozone concentration is low.
Moreover, we can distinguish stratospheric ozone from tropospheric ozone by observing the formation of the ozone gas.
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