The Earth's atmosphere can be roughly divided into five layers.
The troposphere extends from the surface up to a height of about 7 to 20 km (4 to 12 miles). The air pressure decreases with altitude as there is less weight of air above to compress the air underneath.
The air temperature in the troposphere decreases with altitude, at an average rate of about 6.5°C for every kilometre (3.6°F per 1000 feet). At sea level, the average temperature is about 15°C (59°F) while, at the top of the troposphere, the temperature can be as low as -55°C (-67°F) depending on latitude, season, and weather patterns.
The troposphere also contains most of the Earth's water vapour, which produces clouds that reflect both solar radiation back into space, and heat radiation from the Earth's surface, while also transporting prodigious amounts of water and heat over most of the Earth's surface. All of Earth's weather occurs in the troposphere including winds, storms, and frontal systems.
The stratosphere is the second layer of Earth's atmosphere, extending from the troposphere from 7 to 50 km (or 4 to 31 miles). The air temperature increases with altitude, due to the presence of ozone (an unstable molecule of oxygen with three oxygen atoms rather than the normal two), which is created by ultraviolet radiation from the sun. This process absorbs the radiation and heats the surrounding air.
The air pressure is lower than in the troposphere, but it remains relatively constant with altitude. There are very few clouds and they are typically found at high altitudes where temperatures are very low.
The stratosphere is relatively stable, with little mixing between its different layers. This makes it a good location for high-altitude weather balloons and other atmospheric sensors.
The stratosphere contains powerful, high-speed winds known as the stratospheric jet streams, which can impact weather patterns in the troposphere below. They are used, or avoided, by aircraft as they can add or subtract an hour on a transatlantic flight time.
The mesosphere (between 50 and 85 km) is the third layer of the atmosphere. Located above the stratosphere, it is the coldest region of Earth's atmosphere, with temperatures (as low as -100°C) decreasing with altitude. Most meteors, entering the atmosphere, burn up in this layer.
The thermosphere (85 to 600 km) is the fourth layer of the atmosphere, directly above the mesosphere. It contains most of the ionosphere, where ultraviolet solar radiation knocks electrons off molecules creating positively charged ions. This shields life on the Earth's surface from much damaging solar radiation and also acts as radio frequency reflector that permits very long distance radio communications.
Absorbing solar radiation makes the ionosphere very hot with temperatures (increasing with altitude) reaching up to 2,500 degrees C. But the thin atmosphere does not feel warm. The International Space Station and many low Earth orbit satellites are located in the thermosphere.
The exosphere (600 km and above) is the outermost layer; directly above the thermosphere. The atmosphere is very cold and thin, consisting mainly of the lighter gases hydrogen and helium, but they are very spread out so that molecules rarely collide
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Atmospheric
Non-FictionThe eruption of Tonga's underwater volcano, in January 2022, vaporized 150 million tons of seawater and shot a geyser of super heated steam through the stratosphere. The water vapour, a strong greenhouse gas, may increase global temperatures for at...
