How Many Layers Does the Earth’s Atmosphere Have and What are They Called
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere
The troposphere is the lowest layer of the atmosphere, and it is where we live. It extends up to 5 to 10 miles (8 to 15 km) above the surface. It is the densest layer, containing more than half the volume of total air. Most of the atmospheric water vapor and dust are found here. This means that all the weather that we experience occurs at this level, as clouds are formed here. In the troposphere, the temperature falls as we get higher up, and is the lowest at the tropopause that acts as the boundary between this layer and the next. this is where Earth’s jet stream (a narrow, fast, winding air current) is found as well. Lies just above the troposphere, extending up to 31 miles (50 km) high. It is the part of the atmosphere that contains the ozone layer, which is essential for our survival as it blocks the harmful UV rays of the Sun from reaching us. Unlike the troposphere, in this layer, the temperature increases as we go higher. Also, jet aircraft and weather balloons fly in this layer as there is less turbulence. The stratopause acts as the boundary between the stratosphere and the mesosphere. The mesosphere extends from just above the stratosphere to 53-62 miles (85-100 km) high. It is the coldest layer of the atmosphere, with the temperature dropping to its lowest at the boundary between the mesosphere and thermosphere, called the mesopause. Nothing is known about this layer except that meteoroids burn up here, preventing them from reaching the Earth’s surface. This layer extends from the mesopause to about 372 miles (600 km) high. It is the hottest layer of the atmosphere, but the air density is so low that the high temperature cannot be felt at all. Most of the thermosphere is actually considered part of outer space due to this low air density. This is where the Aurora Borealis and Aurora Australis occur. They are caused by collisions between charged particles from space and the air molecules in the thermosphere and can be seen as spectacular displays of light in the sky near the north and south poles respectively. The exosphere extends from the upper boundary of the thermosphere, between 310 and 620 miles (500 and 1,000 km). The exact altitude can vary based on solar activity. Its lower boundary is called exobase or exopause, and this is the altitude above which atmospheric temperature remains almost constant. The exosphere is the least dense layer of the atmosphere, comprised of mostly helium and hydrogen.
