In West Africa, the Dahomey Gap refers to the area of savanna that extends all the way to the coast in Benin, Togo and Ghana, thus separating the forest zone that covers much of the south of the region into two separate parts. These are sometimes called the Guinean forest zone (west of the Gap) and the Congolian Forest Zone (east of Gap). West Africa is the region of western Africa generally considered to include these countries: Benin Burkina Faso Cameroon Côte dIvoire (Ivory Coast) Equatorial Guinea Gabon The Gambia Ghana Guinea Guinea-Bissau Liberia Mali Niger Nigeria Republic of the Congo (Congo-Brazzaville) Senegal Sierra Leone Togo Chad, Mauritania, and... Savanna is a grassland dotted with trees, and occurs in several types of biomes. ...

The major city in the Gap is Accra. Several other cities, such as Kumasi, exist on the fringe of the Gap. Accra, population 1,661,400 (2001), is the capital of Ghana. ... Kumasi is the capital city of the Ashanti Region of Ghana. ...

Causes of dryness

The dryness of the Dahomey Gap is unusual, given that it lies surrounded by a very wet monsoon belt on all sides, and no mountains block moisture. Yet, Accra in the heart of the Gap receives only 720 millimetres (28 inches) of rainfall per year - less than half the amount needed to sustain tropical rainforest (which would be expected at a latitude of 6 ° N). Monsoon in the Vindhya(mountains) in central India A monsoon is a periodic wind, especially in the Indian Ocean and southern Asia. ...

The cause of the dryness of the Dahomey Gap can simply be explained thus:

• In northern winter, high pressure centred on the Sahara sends dry northeasterly trade winds over West Africa, creating a general dry season, including over the Gap.

• In northern summer, an enormous low pressure system known as the monsoon forms over the huge Africa-Asia-Europe landmass. Centred over approximately Rajasthan and prevented by the huge barrier of the Himalayas from moving further west, it extends a strong trough over West Africa. This trough sends warm and saturated westerly winds over West Africa, creating a wet season peaking in June on the coast (as the trough moves north) and in August inland.

• The coast in the region of the highest rainfall (Guinea, Sierra Leone, Liberia) slopes from southeast to northwest. This aspect means that the moist westerlies are forced to shed enormous quantities of moisture, allowing rainforest to thrive despite a distinct dry season.

• In the Dahomey Gap, however, the coast slopes in such a way (northeast to southwest) that the rain-bearing westerlies flow parallel to the coast. This means they are not forced to give up nearly so much moisture, and thus the climate is much drier, with only a brief rainy season in May and June. Consequently, an open savanna prevails adopted to the moderate rainfall and high evaporation in the hot temperatures.

Giuseppe Arcimboldo, Winter, 1573. ... The trade winds are a pattern of wind found in bands around Earths equatorial region. ... Giuseppe Arcimboldo, Summer, 1573. ... Monsoon in the Vindhya(mountains) in central India A monsoon is a periodic wind, especially in the Indian Ocean and southern Asia. ... Rajasthan (राजस्थान) is the geographically largest state in northwestern India. ... The Himalaya is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau. ... In geography, aspect generally refers to the direction to which a mountain slope faces. ... A season is one of the major divisions of the year, generally based on broad climatic patterns. ... The term Parallel has a number of important meanings: Parallel (geometry) occurs in geometry. ... Evaporation is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. ...

Geological history

The Dahomey Gap has only existed in its present form for about four thousand years. For most of the Quaternary, dry conditions due to a much colder Atlantic Ocean (aided by extensive cold currents from ice sheets in Europe and North America have meant that the present-day forest zone has supported very little or no rainforest. In interglacial periods, however, rainfall throughout West Africa has often been so heavy that the Gap has become wet enough to support rainforest, thus eliminating the savanna. The Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1. ... A satellite composite image of Europe Europe is geologically and geographically a peninsula, forming the westernmost part of Eurasia. ... World map showing location of North America A satellite composite image of North America North America is a continent in the northern hemisphere, bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west... Glaciation, often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ...