|Layers in the Earth's Atmosphere|
The atmosphere is made up of several gasses, but is 78.09% Nitrogen, 20.95% Oxygen, between 0.2 and 4% water vapour, plus tiny amounts of Carbon Dioxide, Ozone, Methane, argon, Helium and sulphur dioxide amongst others. The Earth's atmosphere contains several different layers that can be defined according to air temperature or chemical composition. The diagram below displays some of these layers in an average atmosphere. The atmosphere can be split into distinguishable layers, called the Troposphere, the Stratosphere, the Mesosphere and finally closest to space the Thermosphere. These zones are identifiable because of their characteristics properties in relation to temperature and pressure.
The zone in which we live is known as the Troposphere, and this zone influences our daily lives. It contains all of the elements vital to life, plus most of the water vapour in the atmosphere, most of the clouds dust and pollution. Much of the atmospheres “weather” occurs here too. On the diagram we can see that temperature decreases rapidly with increasing distance from the Earth’s surface. This decrease in temperature is the Environmental Lapse rate, which is approximately 6.4°C for every 1000m ascent. This is largely because the Earth is heated from the surface outwards, as it receives incoming solar radiation as UV rays which is converted to heat at the surface (if it is not absorbed by the atmosphere or reflected back out. In some places reflective losses can be great as some surfaces have very high Albedo, that is, the fraction of insolation reflected by a surface, ice and snow have very high albedos. Pressure also decreases with height in this zone, and the amount of Oxygen available decreases (which is why some mountaineers get altitude sickness when mountain climbing). This rate of cooling in the troposphere reasonably stable, but the cooling of different air masses is variable from place to place and from time to time however, and links in with other lapse rates and atmospheric stability.
In contrast to the troposphere, the stratosphere has an increase in temperature with height away from the Earth’s surface, largely due to the presence of a layer of Ozone. Ozone absorbs a lot of incoming solar radiation, and this causes the atmosphere to warm in the stratosphere. Ozone is O3 and is continually destroyed and reformed in this zone. Ozone also protects people on the surface, because it absorbs harmful UV rays that could cause cancers and problems for people’s cataracts. The Stratosphere does have winds, but these are light in the lower layers and increase in strength with height.
In this zone, temperatures fall rapidly with height from 60km a temperature of -5°C is recorded and this fall to -90°C at 80km up. This is largely due to the absence of any materials that can trap the incoming energy from the sun, water vapour, dust and Ozone.
The final layer is the Thermosphere, and this zone has an increase in temperature in height, up to 1500°C, because there is an increasing amount of atomic Oxygen which absorbs Insolation.
Between each of the zones we have Isothermal layers called pauses where temperature barely changes. These are respectively called the Tropopause, the Stratopause, and the Mesopause with increasing distance from the Earth’s surface.
1. Using the diagram
above describe the changes in temperature and pressure with increased
height in the atmosphere. Be sure to use the names of the different layers of the
atmosphere in your answer.
2. Using http://www.geog.ouc.bc.ca/physgeog/contents/7b.html add extra information to your answer.
3. Try to explain the vertical changes in temperature and pressure using Waugh "Geography: an integrated approach" page 188