Tropopause
Topic: Atmosphere: Composition, Structure and Elements of Weather · NCERT: Class 11, Ch 7 "Composition and Structure of Atmosphere"
Meaning
The tropopause is the boundary zone between the troposphere below and the stratosphere above. Within it, temperature stays nearly constant with height. It is about −80°C over the equator and about −45°C over the poles. The equatorial tropopause is colder because it is much higher, at about 18 km compared with about 8 km at the poles. Strong rising air at the equator carries heat higher there. Jet streams, which are fast, narrow bands of wind high in the sky, blow near the tropopause.
Example
Over the equator, for example above Indonesia, tall thunderclouds rise to about 18 km. They flatten out at the very cold tropopause, at about −80°C. Over the Arctic, the same boundary lies at only about 8 km and is warmer, at about −45°C.
Don't confuse with
- Troposphere: this is the lowest layer, where temperature falls with height and all weather happens. The tropopause is only its top boundary.