Geography of Cape Verde - Climate

Climate

A cold Atlantic current produces an arid atmosphere around the archipelago. December–June is cool and dry, with temperatures at sea level averaging 21 °C (69.8 °F); July–November is warm and dry, with temperatures averaging 27 °C (80.6 °F). Although some rain comes during the latter season, rainfall is sparse overall and very erratic. Accumulations are generally around 130 mm (5.12 in) annually in the northern islands and 300 mm (11.81 in) in the south. The archipelago is subject to cyclical droughts; a devastating drought began in 1968 and was broken only briefly in 1975, 1978, 1984, and 1986.

Rainfall is irregular, historically causing periodic droughts and famines. The average precipitation per year in Praia is 240 mm (9.45 in). During the winter, storms blowing from the Sahara sometimes form dense dust clouds that obscure the sun; however, sunny days are the norm year round. The clearest skies are found between February and June, with very little rainfall during these months. Saharan dust, Harmattan wind, laden dust from the Sahara. This occurs between November and March and is generally similar to the "Calima" affecting the Canary Islands.

The ocean near Cape Verde is an area of tropical cyclone formation; since these storms have the whole Atlantic over which to develop as they move westward, they are among the most intense hurricanes, and are called Cape Verde-type hurricanes.

The Cape Verde islands are a very degradated area. Also, most islands do not always get a monsoon. In fact, it is not surprising that some atmospheric precipitation of islands are limited in tropical rain.

If rain arrives, it is usually between August and October. The first "rainy season" brings high temperatures and high humidity that condenses as dew mountain. The other rainy season is between December and June, when the northeast trade winds are common during this season, only altitudes above 600m tend to receive regular rain. The island of Sal receives an average of 0.0mm in May, When the rain come, if it comes, can be very strong. The half of the rain in a year can often fall into a single storm. Due to its proximity to the Sahara, most of the Cape Verde islands are dry, but on islands with high mountains and farther away from the coast, by orography, the humidity is much higher, giving a rainforest habitat, very degraded by the strong human presence. Northeastern slopes of high mountains often receive a lot of rain and Southwest slopes not. This is because they are Umbria areas, situated in the north hillsides or slopes of the mountainous areas, oriented behind the sun in the northern hemisphere, in the shadyside orographic. So the amount of solar radiation that it receive is much lower than it would if it had without the Island's relief which intercepts much of the sun. In terms of botanical ecology, these umbria areas are identified as being cool and moist.

The current north of the Canaries, has a cooling effect on the islands of Cape Verde, making the air temperature more bearable than it would expect in any case at this latitude. Conversely, the islands do not receive the upwellings (cold streams) that affect the West African coast, so the air temperature is cooler than in Senegal, but the sea is actually warmer, because the orographic relief of some islands, as Sao Miguel with steep mountains, cover it with rich woods and luxuriant vegetation where the dense moisture condense and soak the plants, rocks, soil, logs, moss etc.

Hurricanes often begin their training in the waters around the islands of Cape Verde, but it is rare that the strength of the storm reaches close to the islands. A Cape Verde type Hurricane is formed in the area south of the islands, near Sao Miguel, after a tropical wave on the African continent during the rainy season. The storm picks up strength when it crosses the warm waters of Atlantic.

The laurel forest is a type of cloud forest, the cloud forests, are developed preferably about mountains, where the dense moisture from the sea or ocean, is precipitated by the action of the relief. Opposing the terrain to a front of warm, moist air mass, it forces to increase the height above sea level of that body wet and warm air mass, which cools and decreases the dew point, causing it to condense part of the moisture that falls as rain or fog, creating an habitat especially cool, saturated with moisture in the air and soil.

It is the balance between the dry and warm influence of the subtropical anticyclone, hot and dry summer and orography the responsible for carrying cool wet. As latitude increases, this increases the impact of the storms, which in its journey from west to east, swept the western coasts of continents, dumping heavy rains as carrying high humidity. Precipitation multiply if these air masses are crossing mountains in the way. The resulting climate is wetter, but with an annual oscillation of the temperature moderated by the proximity of the ocean. Appear mostly occupying favorable areas named geographically Umbrias, this is north hillsides or slopes of the mountainous areas that are oriented behind the sun, be cause the islands are in the northern hemisphere, between 600 and 1500 meters, thus benefiting from the humidity provided by the trade winds to form such a sea of clouds. In its botanical ecology, the mountain umbria is identified with cool and moisture.