For its position with respect to the Equator Africa is the continent with the greatest tropicality; furthermore, again with respect to the equator, there is a zonal distribution, symmetrical to the South and North of it, of the climatic conditions, a fact essentially due to the absence of reliefs and to the open morphology of the continental surfaces. Over the year, the conditions alternate in the two parts in relation to the zenith situation that occurs in the summer (boreal summer) in the North, and in the winter in South. The equatorial zone is the most stable: that is, it constitutes the belt of the ” intertropical convergences ”, where the trade winds converge from Northeast and Southeast, attracted by the low pressures that are established there due to the strong and constant warming. This circulation towards the Equator is fed by areas of high tropical pressure, both maritime and continental: Sahara, where in winter there is an area of high pressure, very stable; among other things, it gives rise to harmattan, the wind that blows in winter over Sudanese Africa attracted by the low pressures that form in the Guinean region. An analogous phenomenon, but more reduced given the smaller extension of continental surfaces, occurs in southern Africa in summer, that is, in the inverted season. Always in the summer in the Sahara the situation is reversed: the high pressures move towards the North and this draws humid air from the Gulf of Guinea. According to Countryaah.com, East Africa is subjected to a monsoon-like regime, exposed to the influences of the Indian Ocean, while in northern Africa, especially from Morocco to Tunisia, there is a Mediterranean regime, with anticyclonic areas in summer (they are responsible for the ” Etesii winds ”which blow towards the African coasts) and low winter pressures, with an inflow of unstable air from the Atlantic. This general mechanism of circulation and exchange basically regulates the rainfall regime. In the equatorial belt they are continuous, only with a slight attenuation in the winter or summer months respectively in the N and S; the rains are always above 1800 mm, with exceptional maximums in the Gulf of Guinea and in particular on the slopes of Mount Cameroon, where up to 10,000 mm per year can be recorded. High rainfall, but tends to be distributed in distinct seasons, is also found in Guinean Africa, sheltered from Saharan influences and well exposed to oceanic air masses. On the rest of the continent there is a two-season tropical regime, well marked the more the tropicality is accentuated.
The rainy season (which in Africa is called “winter”) begins with violent events, thunderstorms, and is preceded by a short rainy season, which is very irregular (small rainy season). Precipitation is concentrated in the summer months to the N of the Equator, in the winter months (austral summer) to S. The duration of the rainy season decreases moving away from the Equator; the greatest rainfall occurs in the period when the sun is at its zenith. Quantitatively, we pass from the values of the equatorial belt to 500 mm (isoieta with which in Sudanese Africa the sahel) and to the 250 mm which represent the beginning of the desert areas; in the Sahara there are many places where precipitation does not occur for years. It is interesting to note that in all tropical Africa the environmental conditions derive not so much from the quantity of precipitation as from the fact that they are concentrated in a short period, which forces plant life to a particular adaptation to prolonged drought. The temperature regime is connected to the trend of the rains which, although varying according to the areas, are generally high, so as to justify the fame of the continent, and which often contribute to making its climate uncomfortable for the white man, although the main repulsive factor is the high humidity of the equatorial areas (up to 90%). In these there are constant values (25-26 ºC) both daily and annually in relation to the continuous nebulosity, the absence of winds, the humidity. In the band of alternating seasons, seasonal and daily values are more differentiated as one proceeds away from the Equator; in desert areas, day trips reach up to 40 ºC. Mitigated thermal conditions (summer averages about 25 ºC, winter about 13-15 ºC) occur in northern Africa and in the extreme southern tip of the continent, given their climatic characteristics of the Mediterranean type. The local climate conditions are also influenced by the altitude (on the Atlas and the Saharan massifs of Ahaggar and Tibesti can occur snowfalls, common on the peaks of the great equatorial mountains), continentality and, along the coasts, the cold sea currents of the Canaries and Benguela and the warm one of Mozambique.