The Earth's atmosphere is divided into five primary layers, each characterized by distinct properties, behaviors, and composition. Here’s a brief overview of each layer:
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Troposphere:
- Altitude: Extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles), varying with latitude and weather conditions.
- Properties: The troposphere contains approximately 75% of the atmosphere's mass and most of the water vapor, which is essential for weather formation. Temperature generally decreases with altitude in this layer, with the lowest temperatures occurring at the tropopause (the boundary between the troposphere and the stratosphere). Weather phenomena, clouds, and winds all occur in this layer.
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Stratosphere:
- Altitude: Extends from the tropopause (about 10 to 15 km) up to about 50 kilometers (31 miles) above the Earth's surface.
- Properties: The stratosphere is characterized by a temperature inversion, meaning temperature increases with altitude. This is due to the presence of the ozone layer, which absorbs and scatters ultraviolet solar radiation. The stratosphere is relatively stable and does not experience the turbulent weather phenomena found in the troposphere.
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Mesosphere:
- Altitude: Ranges from about 50 kilometers (31 miles) to 85 kilometers (53 miles).
- Properties: Temperatures in the mesosphere decrease with altitude, reaching the coldest temperatures in the Earth's atmosphere (as low as -90°C or -130°F at the mesopause). This layer is where most meteors burn up upon entering the Earth's atmosphere, and it contains few molecules, leading to very low air pressure.
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Thermosphere:
- Altitude: Extends from about 85 kilometers (53 miles) to between 500 and 1,000 kilometers (310 to 620 miles).
- Properties: In the thermosphere, temperatures increase significantly with altitude, reaching up to 2,500°C (4,500°F) or more, due to the absorption of intense solar radiation. Despite these high temperatures, the air is extremely thin, and you wouldn't feel hot here as a result. The thermosphere is also where the auroras occur, and it contains the ionosphere, a region crucial for radio communication.
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Exosphere:
- Altitude: Extends from around 600 kilometers (370 miles) to roughly 10,000 kilometers (6,200 miles).
- Properties: The exosphere is the outermost layer of the Earth's atmosphere, where atmospheric particles are so sparse that they can travel hundreds of kilometers without colliding with one another. The temperature is difficult to define due to low particle density, but it can be considered very high. This layer gradually fades into the vacuum of space and is where satellites orbit the Earth.
Each layer plays a critical role in protecting life on Earth and contributing to various atmospheric and climatic processes.
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