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Layers of the Earth’s Atmosphere

The atmosphere of the earth is the layer of gases (commonly called air) that surrounds the earth and creates an inhabitable environment, maintains temperature, causes weather, and protects its inhabitants from solar radiation.

How Many Layers Does the Earth’s Atmosphere Have and What are They Called

Layers of the Atmosphere

Scientists divide the atmosphere into 5 different layers based on factors like air pressure and density. The names of these layers, in order of lowest to highest, are:

  1. Troposphere
  2. Stratosphere
  3. Mesosphere
  4. Thermosphere
  5. Exosphere  

1. Troposphere

Temperature: 62°F (17°C) around the lowest point  to -60°F (-51°C) near the top

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.

2. Stratosphere

Temperature: -60°F (-51°C) near the tropopause to 5°F (-15°C) near the next layer

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.

3. Mesosphere

Temperature: Ranges from 32°F (0°C) to -130°F (-90°C), the lowest temperature found on Earth

The mesosphere extends from just above the stratosphere to 53 miles (85 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. Not much is known about this layer except that meteoroids burn up here, which prevents them from reaching the Earth’s surface.

4. Thermosphere

Temperature: 932°F (500°C) to 3,632°F (2,000°C) – depends on how hot the sun is

The thermosphere 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.

5. Exosphere

Temperature: Up to 2,700°F (1,500°C)

The exosphere extends from the thermosphere to about 6,200 miles (10,000 km) and is the upper limit of the atmosphere. 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.

FAQs

Q1. What layer of the atmosphere do satellites orbit the earth?

Ans. The thermosphere is where satellites and space stations, like the International Space Station, orbit the Earth.

Q2. Airplanes fly in what layer of the atmosphere?

Ans. Airplanes and other commercial aircraft fly in the troposphere.

Q3. At what height does outer space start?

Ans. The Kármán line, at 62 miles (100 km) above the surface, is often said to be the point at which outer space starts.

Q4. What is the ionosphere and where does it lie in the atmosphere?

Ans. The ionosphere is a layer of charged particles (ions) that stretches from 48 km above the surface to around 965 km. It stretches over the mesosphere, most of the thermosphere, and some parts of the stratosphere. It is important for radio communications and is responsible for auroras. Its size varies with daytime and nighttime.

References:

  1. Earth’s Atmosphere: Composition, Climate & Weather – Space.com
  2. Earth’s Atmospheric Layers – NASA.gov
  3. Layers of the Atmosphere – NIWA.co.nz
  4. The Earth’s Ionosphere – Solar-center.stanford.edu
  5. Layers of Earth’s Atmosphere – Scied.ucar.edu

Article was last reviewed on Thursday, November 26, 2020

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