Troposphere
Written by Tega Jessa
The troposphere is the lowest part of the Earth's atmosphere. It gets its name from the Greek word Tropos which mean mixing. That is a perfect description for the troposphere. As the closest part of the atmosphere to the earth it is subject to the mixing caused by the friction between air and the Earth surface. The zone where this happens in the troposphere is called the planetary boundary layer.
The majority of the clouds and water vapor in the atmosphere occurs in the troposphere. The are several reasons for why this happens. One is dust. The friction of moving air over the surface of the Earth kicks up a lot of dust. Clouds form around these particles of dirt in the atmosphere. Without them precipitation such as rain or snow also would not be able to form. The water vapor come from the evaporation of water from the Earth's surface which starts the water cycle that helps purify the world's waters.
The troposphere is also very warm, especially in comparison to the higher levels of the atmosphere. This is due the heat produced by the surface of the Earth. It happens in a pretty round about way. The Earth which on average has a low reflection ratio, absorbs a lot of sunlight and this solar energy is transformed into heat that rises back up transfered by air as it rises through convection and the evaporation of water vapor. This is what makes the troposphere warm. However, there is a limit to the heating effect. There is a region between the troposphere and the stratosphere where the temperature abruptly drops. This region is the boundary between the two levels of the atmosphere and it called the tropopause.
Despite its importance to life on Earth it is quite a thin shell when compared with the rest of the atmosphere. The troposphere is only 11 km in middle latitudes, 12 in tropical regions, and 7 at the poles. The planetary boundary layer where most life lives is even small being just 2 km above sea level.
The troposphere is important because it is one of the key parts of the atmosphere that maintain the Earth's natural thermostat allowing for life to exist. It also host the water cycle and pressure systems which help purify and deliver water to most regions of the earth. So as you can see the troposphere does a great deal to help maintain the Earth.
If you enjoyed this article there are others on Universe Today that you will enjoy. There is a great article about cloud types. There is also a great article about the composition of the Earth's atmosphere
There are also some great resources on the web. There is a great article about the troposphere on the UCAR.edu site. There is also a great article on this site.
You can also check out Astronomy Cast. Episode 151 is on the atmosphere.
Filed under: Astronomy
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