Earth’s climate (Part 1)

Earth’s climate depends on many factors, starting from the region, instantaneous atmospherical conditions, seasons. We can distinguish different type of climate, depending on the intensity of the sunshine, temperature,  wind,  precipitation,  evaporation, the frequency of storms and seasonal data.

The Sunshine or Solar Radiations

The sunshine is not uniform in the earth’s surface. The equatorial belt benefits from important solar radiations all year while other regions close from poles benefit from important differences of radiation between winter and summer. As for poles, they experience permanent cold climate. Along the equator, the land is warm, but the further you go from the equator, the most intense the variations of temperature are going to be.

General Atmospheric Circulation

The important heat that prevails along the equator means that the air is warming up and dilates then rise to lead itself to poles. Then, a part of that air return back to equator according to the process of circulation named Hadley cell. The subtropical belt is an important high-pressure cell from which the winds head toward poles passing by more temperate latitudes. However, Cold and dense air coming from poles is also passing by these latitudes to lead itself to the equator. The collision of these fronts with masses of tropical air in temperate areas gives birth to cyclones.


Subtropical Belt
Subtropical Belt

Type of climate

Among the various climate classifications that have been proposed, the most popular one has been developed by Wladimir Koppen which globally distributed the different climates in 5 classes: A, B, C, D and E. A, C and D designate humid climates, A being the hottest and situated in the tropics, C corresponding to the climate in warm temperate regions. D regroups cold climates which have regular snowfall during winter. Arid climates, both tropical and temperate are classified in B and E includes climates in polar and glacial regions. For further information about classes of climate, click here.


Tropical Humid climates

The climate of type A covers a zone situated between 25 degrees north latitude and 25 degrees south latitude. These tropic and humid climates are characterized by an important pluviometry and high temperature all year. Regions further from the equator are characterized by hot summer and cold winter. The Southeast Asian tropical climate is a typical climate of type A. It is characterized by very rainy seasons preceded and followed by months of drought. In vast regions of India and Southeast Asia, most of the rainfall is between June and September while particularly drought months are between March and May.


Desert Climates

Desert climates concern the subtropical and temperate zones and are, according to Koppen, of type B. These regions are characterized by very drought temperature and rare rainfall. Hot deserts are found in subtropical regions, in a region starting from North Africa(Sahara) and Middl East going up to the West side of India (Thar desert). Koppen also added the Austalian desert to that list. These deserts exhibit large daily temperature differences: it can be very hot during the day, and relatively cold during the night

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