Earth's atmosphere is divided into five main layers(Primary layers):
|Exosphere||700 to 10,000 km||
Outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere).
The exosphere merges with the emptiness of outer space, where there is no atmosphere.
The exosphere contains most of the satellites orbiting Earth.
|Thermosphere||80 to 700 km||
It is also referred to as the exobase.
The lower part of the thermosphere, from 80 to 550 kilometres (50 to 342 mi) above Earth's surface, contains the ionosphere.
This atmospheric layer undergoes a gradual increase in temperature with height.
The temperature of this layer can rise as high as 1500 °C.
This layer is completely cloudless and free of water vapor.
Aurora borealis and Aurora australis are occasionally seen in the thermosphere.
The International Space Station orbits in this layer, between 320 and 380 km (200 and 240 mi).
|Mesosphere||50 to 80 km||
It is the coldest place on Earth and has an average temperature around −85 °C (−120 °F; 190 K).
Highest clouds in the atmosphere are found in this layer.
The mesosphere is also the layer where most meteors burn up upon atmospheric entrance.
It is too high above Earth to be accessible to aircraft and balloons, and too low to permit orbital spacecraft.
The mesosphere is mainly accessed by sounding rockets.
|Stratosphere||12 to 50 km||
The atmospheric pressure at the top of the stratosphere is roughly 1/1000 the pressure at sea level.
It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations of that gas.
The temperatures rises with increasing altitude, caused by the absorption of ultraviolet radiation (UV) radiation from the Sun by the ozone layer, which restricts turbulence and mixing.
The stratospheric temperature profile creates very stable atmospheric conditions, so the stratosphere lacks the weather-producing air turbulence that is so prevalent in the troposphere. Consequently, the stratosphere is almost completely free of clouds and other forms of weather.
However, polar stratospheric or nacreous clouds are occasionally seen in the lower part of this layer of the atmosphere where the air is coldest.
This is the highest layer that can be accessed by jet-powered aircraft.
|Troposphere||0 to 12 km||
The troposphere is the lowest layer of Earth's atmosphere.
Temperature declines with increasing altitude in the troposphere because the troposphere is mostly heated through energy transfer from the surface. Thus, the lowest part of the troposphere (i.e. Earth's surface) is typically the warmest section of the troposphere.
The troposphere contains roughly 80% of the mass of Earth's atmosphere.
The troposphere is denser than all its overlying atmospheric layers because a larger atmospheric weight sits on top of the troposphere and causes it to be most severely compressed.
Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (18,000 ft) of the troposphere.
It has basically all the weather-associated cloud genus types generated by active wind circulation, although very tall cumulonimbus thunder clouds can penetrate the tropopause from below and rise into the lower part of the stratosphere.
Most conventional aviation activity takes place in the troposphere, and it is the only layer that can be accessed by propeller-driven aircraft.
Ozone concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere.
Extent: 15–35 km
Thickness varies seasonally and geographically.
About 90% of the ozone in Earth's atmosphere is contained in the stratosphere.
The layer is ionized by solar radiation.
This layer is responsible for auroras.
During daytime hours, it stretches from 50 to 1,000 km and includes the mesosphere, thermosphere, and parts of the exosphere. However, ionization in the mesosphere largely ceases during the night, so auroras are normally seen only in the thermosphere and lower exosphere.
The ionosphere forms the inner edge of the magnetosphere. It has practical importance because it influences, radio propagation on Earth.