Turbopause
Encyclopedia
The turbopause marks the altitude in the Earth's atmosphere
below which turbulent mixing
dominates. The region below the turbopause is known as the homosphere, where the chemical constituents are well mixed and display identical height distributions; in other words, the chemical composition of the atmosphere remains constant in this region for chemical species which have long mean residence times. Highly reactive chemicals tend to exhibit great concentration variability throughout the atmosphere, whereas unreactive species will exhibit more homogeneous concentrations. The region above the turbopause is the heterosphere, where molecular diffusion
dominates and the chemical composition of the atmosphere varies according to chemical species.
The turbopause lies near the mesopause
, at the intersection of the mesosphere
and the thermosphere
, at an altitude of roughly 100 km.
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
below which turbulent mixing
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
dominates. The region below the turbopause is known as the homosphere, where the chemical constituents are well mixed and display identical height distributions; in other words, the chemical composition of the atmosphere remains constant in this region for chemical species which have long mean residence times. Highly reactive chemicals tend to exhibit great concentration variability throughout the atmosphere, whereas unreactive species will exhibit more homogeneous concentrations. The region above the turbopause is the heterosphere, where molecular diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
dominates and the chemical composition of the atmosphere varies according to chemical species.
The turbopause lies near the mesopause
Mesopause
The mesopause is the temperature minimum at the boundary between the mesosphere and the thermosphere atmospheric regions. Due to the lack of solar heating and very strong radiative cooling from carbon dioxide, the mesopause is the coldest place on Earth with temperatures as low as -100°C...
, at the intersection of the mesosphere
Mesosphere
The mesosphere is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere. In the mesosphere temperature decreases with increasing height. The upper boundary of the mesosphere is the mesopause, which can be the coldest naturally occurring...
and the thermosphere
Thermosphere
The thermosphere is the biggest of all the layers of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. The International Space Station has a stable orbit within the middle of the thermosphere, between...
, at an altitude of roughly 100 km.