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Tropics is the word derived generally from Tropic of Cancer and Capricorn, the parallels at a latitude of 230 which shows the outer limit of the areas where the sun can ever be in zenith.
Tropic are the regions of the Earth around the equator, varying in width from about 400 to 600 in latitude; these areas are located between the tropic of cancer in the Northern hemisphere and the tropic Capricorn in the Southern hemisphere. These are places on the earth where the sun reaches a point directly overhead at least once in a year. The tropic is also called tropical zoneand thetorrid zone.
It is generally understood that that the tropical areas are mainly located between these two line (Tropics of Cancer and Capricorn), they are therefore the region of low latitudes, but the outer limits of the low latitude are not easily recognized because the Tropics of cancer and of Capricorn themselves are unsuitable a boundaries. They are too rigid; some regions with clear tropical characteristic 230 while, on the other hand some clearly non-tropical area are found much closer to the equator. The best way to determine the outer limits of the tropical areas is therefore to use common characteristics which distinguish these regions from the rest of the world. As latitude is the main factor controlling climatic conditions, the most important of these common features are those of climate. Other typical characteristics of the low latitudes such as those of vegetation, soil, agriculture and economic development are all directly or indirectly related to their common climatic conditions.
The tropics receive the most direct sunlight throughout the year which is believed to be favourable to plant and animal life, provided there is adequate moisture or precipitation. One of the problems with the tropics is that the soils are usually of poor quality and the nutrients have been leached out.
In economic terms, most tropical regions belong to the group of developing nations, which are characterized by low standards of living, a strong concentration on agriculture and predominance of production of raw materials rather than industrial products. The poverty of the tropical countries is illustrated by the fact that more than two-third of them have a Gross National Product below the world median of $310 per capita.
Tropical agriculture is of course largely controlled by climatic conditions. It is mainly devoted to the growing of food crops such as rice, maize cassava, coconuts, banana, groundnuts, sorghums, palm oil and cocoa. Most of these crops are produced on a subsistence basis.
Politically, the tropical countries are much more important than they are economically. This is not solely the result of their numbers over 50 countries represented in the United Nations are situated in the tropics), their political significance is also the consequence of their common policy; their united stand is frequently independent of the big power blocks. This attitude is largely due to common history of colonial domination. One of the main origins of colonialism was the desire of the European countries to control the production and trade of the tropical agricultural products. Colonial rule was therefore heavily concentrated in the tropics.
Without any doubt, the most important common climatic feature of the tropics is the absence of a cold season, this is usually represented by an old phrase where winter never come. To define the tropics by this lack of a winter season cannot be done with a simple temperature limit. However, in the tropics, climatic conditions varies gradually over long distances and moreover vary a great deal from year to year. The tropics is often assumed to include only regions where sufficient rain is received to carry out most forms of crop production without any form of irrigation. Tropical regions only experience two seasons in a year “hot” and “wet seasons”, especially where the seasons are made by monsoons.
According to Koppens classification of climate for instance, the mean temperature is 18 0C for the coldest month of the year. This method would exclude the tropical highlands, where temperatures frequently remain well below this limit; yet these areas are truly tropical because they experience no winter. They can easily be included in the tropics by not using the actual temperatures but temperature reduced to sea level.
Countries in the Tropics
Some of the countries in the tropic include Mexico, Malaysia,Philippines,Singapore,India, Thailand, Nigeria,Kenya, Ghana, Zambia,Burkina Faso, Cote d’Ivoire,Bolivia, Costa Rica, Brazil, The Gambia, Bahamas, Guinea, Liberia, Mali, Mauritania, Niger etc.