Everything about The Stratosphere totally explained
The
stratosphere is the second major layer of
Earth's atmosphere, just above the
troposphere, and below the
mesosphere. It is
stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler higher up and warmer farther down. The border of the troposphere and stratosphere, the
tropopause, is marked by where this inversion begins, which in terms of
atmospheric thermodynamics is the
equilibrium level. The stratosphere is situated between about 10 km (6 miles) and 50 km (31 miles)
altitude above the surface at moderate latitudes, while at the
poles it starts at about 8 km (5 miles) altitude.
The stratosphere is layered in temperature because it's heated from above by absorption of
ultraviolet radiation from the
Sun. Within this layer, temperature increases as altitude increases (see
temperature inversion); the top of the stratosphere has a temperature of about 270
K (−3
°C or 26.6
°F), just slightly below the freezing point of water. This top is called the
stratopause, above which temperature again decreases with height. The vertical
stratification, with warmer layers above and cooler layers below, makes the stratosphere
dynamically stable: there's no regular
convection and associated
turbulence in this part of the atmosphere. The heating is caused by an
ozone layer that absorbs solar
ultraviolet radiation, heating the upper layers of the stratosphere. The base of the stratosphere occurs where heating by
conduction from above and heating by convection from below (through the troposphere) balance out; hence, the stratosphere begins at lower altitudes near the poles due to the lower ground
temperature there.
Commercial
airliners typically cruise at an altitude near 10 km in temperate latitudes, in the lower reaches of the stratosphere. They do this to stay above any hard weather. This is to avoid atmospheric
turbulence from the
convection in the
troposphere. Turbulence experienced in the cruise phase of flight is often caused by
convective overshoot from the troposphere below. Similarly, most
gliders soar on thermal
plumes that rise through the troposphere above warm patches of ground; these plumes end at the base of the stratosphere, setting a limit to how high gliders can fly in most parts of the world. (Some gliders do fly higher, using
ridge lift from mountain ranges to lift them into the stratosphere.)
The stratosphere is a region of intense interactions among radiative,
dynamical, and chemical processes, in which horizontal mixing of gaseous components proceeds much more rapidly than vertical mixing.
An interesting feature of stratospheric circulation is the
quasi-Biennial Oscillation (QBO) in the tropical latitudes, which is driven by
gravity waves that are convectively generated in the
troposphere. The QBO induces a
secondary circulation that's important for the global stratospheric transport of tracers such as
ozone or
water vapor.
In northern hemispheric winter,
sudden stratospheric warmings can often be observed which are caused by the absorption of
Rossby waves in the stratosphere.
Further Information
Get more info on 'Stratosphere'.
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