Hadley cell
Hadley cell is a term from meteorology that describes a model of a circulation pattern within the troposphere between the subtropical high pressure belt and the equator . The Hadley cell was named after George Hadley who published this hypothesis in 1735.
Because the sun is constantly close to the zenith in the equatorial region (67 ° –90 ° angle of incidence), the air masses close to the ground warm up here the most. The warmed air loses its density (expands) and rises, creating a pronounced, earth-encompassing low pressure channel.
When ascending, the air cools with increasing altitude. At the tropopause , around 18 kilometers above sea level, it flows north and south due to the comparatively high air pressure. The air cools down further and loses altitude. Due to the incoming air masses, the air pressure increases near the ground, and the subtropical high pressure belt is formed . From here, the air follows the pressure gradient and flows back into the low pressure trough near the equator, in the area of the zenith of the sun. The air masses that meet there from north and south form the intertropical convergence zone (ITC), which forces the air to rise again. A large-scale air cycle is formed.
The resulting winds close to the ground are known as trade winds .
See also
swell
- G. Hadley: Concerning the cause of the general trade winds. In: Philosophical Transactions cvvx. Volume 39, 1735, pp. 58-62.
- Anne Dallmeyer: Hadley Cell. Meteorological seminar, 2006. ( mi.uni-hamburg.de ( Memento from February 1, 2012 in the Internet Archive ), PDF file; 137 kB)