The Earth's atmosphere can be divided into five main layers based on altitude: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
1. Troposphere: This is the lowest layer of the atmosphere, extending from the Earth's surface up to approximately 8-15 kilometers (depending on the location). The composition of gases in the troposphere is mostly nitrogen (approximately 78%) and oxygen (approximately 21%), with small amounts of other gases such as carbon dioxide, water vapor, and trace amounts of various pollutants. As altitude increases within the troposphere, the temperature generally decreases at an average rate of about 6.5 degrees Celsius per kilometer.
2. Stratosphere: Above the troposphere, the stratosphere extends from about 15 to 50 kilometers in altitude. Here, the composition is similar to the troposphere, with most of the gases being nitrogen and oxygen. However, the stratosphere is notable for a layer of ozone (O3) located approximately 20-30 kilometers above the surface, which plays a crucial role in absorbing and blocking harmful ultraviolet (UV) radiation from the Sun. Unlike the troposphere, temperature generally increases with altitude in the stratosphere due to the presence of ozone.
3. Mesosphere: The mesosphere lies between the altitudes of 50 and 85 kilometers above the Earth's surface. It contains predominantly molecular nitrogen and oxygen, with some carbon dioxide and water vapor at very low levels. In this layer, the temperature decreases with increasing altitude, reaching extremely low temperatures, often dropping below -90 degrees Celsius. The mesosphere is also where meteors burn up upon entry into the Earth's atmosphere.
4. Thermosphere: Starting at around 85 kilometers and extending to about 600 kilometers, the thermosphere is characterized by extremely low gas densities. Although the composition remains similar to the previous layers, with nitrogen and oxygen being the primary components, the density of molecules is so low that individual particles rarely collide. Consequently, despite the low density, the temperature in this layer increases significantly with altitude. In the upper thermosphere, temperatures can reach around 2,500 degrees Celsius due to the absorption of high-energy solar radiation.
5. Exosphere: The exosphere is the outermost layer of the Earth's atmosphere, beginning around 600 kilometers and extending to thousands of kilometers or more. In this layer, the density of gas molecules is extremely low, so much so that individual particles can escape into space. The composition consists primarily of hydrogen and helium, along with trace amounts of other gases. Due to minimal molecular collisions, the temperature in the exosphere continues to increase, but the actual temperature is difficult to determine, as it mostly refers to the energy of the particles rather than the ambient temperature.
Overall, the different atmospheric layers exhibit variations in gas composition, temperature changes with altitude, and unique characteristics that play a crucial role in weather patterns, climate, and the protection of life on Earth.
Analyse the different compositions and structure of the atmosphere by referring to the altitude, composition of the gas and changes in the atmospheric temperature
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