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Several layers can be distinguished in the atmosphere based on characteristics such as temperature and composition, namely the troposphere, stratosphere, mesosphere, thermosphere (formally the ionosphere) and exosphere. Air composition, temperature and atmospheric pressure vary with altitude.
As a result, it is the least-understood part of the atmosphere, resulting in the humorous moniker ignorosphere. [20] [21] The presence of red sprites and blue jets (electrical discharges or lightning within the lower mesosphere), noctilucent clouds, and density shears within this poorly understood layer are of current scientific interest.
Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are not to scale. The stratosphere (/ ˈ s t r æ t ə ˌ s f ɪər,-t oʊ-/) is the second-lowest layer of the atmosphere of Earth, located above the troposphere and below the mesosphere.
The heterosphere is the layer of an atmosphere where gases are separated out by molecular diffusion with increasing altitude such that lighter species become more abundant relative to heavier species. The heavier molecules and atoms tend to be present in the lower layers of the heterosphere while the lighter ones are present higher up.
The layer has the largest concentration of nitrogen. The atmosphere of the Earth is in five layers: (i) the exosphere at 600+ km; (ii) the thermosphere at 600 km; (iii) the mesosphere at 95–120 km; (iv) the stratosphere at 50–60 km; and (v) the troposphere at 8–15 km.
The layers are to scale. From the Earth's surface to the top of the stratosphere (50km) is just under 1% of Earth's radius. The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision ...
The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.
The troposphere is the lowest layer of the atmosphere. This extends from the planetary surface to the bottom of the stratosphere. The troposphere contains 75–80% of the mass of the atmosphere, [9] and is the atmospheric layer wherein the weather occurs; the height of the troposphere varies between 17 km at the equator and 7.0 km at the poles.