rising air. The equatorial regions of the Hadley cells are characterized by high
humidity, high clouds, and heavy rains. The monthly average temperatures are
around 90°F (32°C) at sea level, and there is no winter. The vegetation is tropical
rainforest. Temperature variation from day to night (diurnal) is greater than from
season to season.
Figure 2.8 The Hadley, Ferrel, and Polar cellsSubtropical regions of the Hadley cell are characterized by low relative
humidity, little cloud formation, high ocean evaporation due to low humidity,
and many of the world’s deserts. The climate is characterized by warm to hot
summers and mild winters.
The tropical wet and dry (or savanna) climate has a dry season more than
two months long. Annual losses of water through evaporation in this region
exceed annual water gains from precipitation.