The tropics are a region of the
Earth surrounding the Equator. They
are delimited in latitude by the
Tropic of Cancer
Tropic of Cancer in the Northern
Hemisphere at 23°26′12.9″ (or 23.43692°) N and
Tropic of Capricorn
Tropic of Capricorn in the
Southern Hemisphere at
23°26′12.9″ (or 23.43692°) S; these latitudes
correspond to the axial tilt of the Earth. The tropics are also
referred to as the tropical zone and the torrid zone (see geographical
zone). The tropics include all the areas on the
Earth where the Sun
contacts the zenith, a point directly overhead, at least once during
the solar year (which is a subsolar point).
The tropics are distinguished from the other climatic and biomatic
regions of Earth, which are the middle latitudes and the polar regions
on either side of the equatorial zone.
The tropics comprise 40% of the Earth's surface area and contain
36% of the Earth's landmass.As of 2014[update], the region is home
to 40% of the world population, and this figure is projected to reach
50% by the late 2030s.
1 Seasons and climate
4 See also
6 External links
Seasons and climate
Tropical climate and Wet season
A graph showing the zonally averaged monthly precipitation. The
tropics receive more precipitation than higher latitudes. The
precipitation maximum, which follows the solar equator through the
year, is under the rising branch of the Hadley circulation; the
sub-tropical minima are under the descending branch and cause the
Aerial view of Bora Bora, French Polynesia
Tropical sunset over the sea in Kota Kinabalu, Malaysia
"Tropical" is sometimes used in a general sense for a tropical climate
to mean warm to hot and moist year-round, often with the sense of lush
Many tropical areas have a dry and wet season. The wet season, rainy
season or green season is the time of year, ranging from one or more
months, when most of the average annual rainfall in a region falls.
Areas with wet seasons are disseminated across portions of the tropics
and subtropics. Under the Köppen climate classification, for
tropical climates, a wet-season month is defined as a month where
average precipitation is 60 millimetres (2.4 in) or more.
Tropical rainforests technically do not have dry or wet seasons, since
their rainfall is equally distributed through the year. Some areas
with pronounced rainy seasons see a break in rainfall during
mid-season when the intertropical convergence zone or monsoon trough
moves poleward of their location during the middle of the warm
season; typical vegetation in these areas ranges from moist
seasonal tropical forests to savannahs.
When the wet season occurs during the warm season, or summer,
precipitation falls mainly during the late afternoon and early evening
hours. The wet season is a time when air quality improves, freshwater
quality improves and vegetation grows significantly, leading to crop
yields late in the season. Floods cause rivers to overflow their
banks, and some animals to retreat to higher ground.
diminish and erosion increases. The incidence of malaria increases in
areas where the rainy season coincides with high temperatures. Animals
have adaptation and survival strategies for the wetter regime.
Unfortunately, the previous dry season leads to food shortages into
the wet season, as the crops have yet to mature.
However, regions within the tropics may well not have a tropical
climate. Under the Köppen climate classification, much of the area
within the geographical tropics is classed not as "tropical" but as
"dry" (arid or semi-arid), including the
Sahara Desert, the Atacama
Desert and Australian Outback. Also, there are alpine tundra and
snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, and the
Andes as far south as the northernmost parts of
Chile and Argentina.
Coconut palms in the warm, tropical climate of northern Brazil
Tropical forest near Fonds-Saint-Denis, Martinique
Tropical plants and animals are those species native to the tropics.
Tropical ecosystems may consist of tropical rainforests, seasonal
tropical forests, dry (often deciduous) forests, spiny forests, desert
and other habitat types. There are often significant areas of
biodiversity, and species endemism present, particularly in
rainforests and seasonal forests. Some examples of important
biodiversity and high endemism ecosystems are El Yunque National
Forest in Puerto Rico, Costa Rican and Nicaraguan rainforests, Amazon
Rainforest territories of several South American countries, Madagascar
dry deciduous forests, the
Waterberg Biosphere of South Africa, and
Madagascar rainforests. Often the soils of tropical forests
are low in nutrient content, making them quite vulnerable to
slash-and-burn deforestation techniques, which are sometimes an
element of shifting cultivation agricultural systems.
In biogeography, the tropics are divided into Paleotropics (Africa,
Asia and Australia) and Neotropics (Caribbean, Central America, and
South America). Together, they are sometimes referred to as the
Pantropic. The Neotropical region should not be confused with the
ecozone of the same name; in the Old World, there is no such
ambiguity, as the Paleotropics correspond to the Afrotropical,
Indomalayan, and partly the Australasian and Oceanic ecozones.
"Tropicality" refers to the geographic imagery that many people
outside the tropics have of that region. The idea of tropicality
gained renewed interest in modern geographical discourse when French
Pierre Gourou published Les Pays Tropicaux (The Tropical
World, in English), in the late 1940s.
Tropicality encompasses at least two contradictory imageries. One is
that the tropics represent a Garden of Eden, a heaven on Earth;
the alternative is that the tropics are primitive and essentially
lawless. The latter view was often discussed in Western
literature—more so than the first.
Western scholars also theorized about the reasons that tropical areas
were deemed "inferior" to regions in the Northern Hemisphere. A
popular explanation focused on the differences in climate—tropical
regions typically have much warmer weather than northern regions. This
theme led some scholars, including Gourou, to argue that warmer
climates correlate to primitive indigenous populations lacking control
over nature, compared to northern populations having "mastered
Tropical marine climate
^ "How much land is in the tropics?". God Plays Dice. 2007-12-04.
^ "tropics". National Geographic Encyclopedia. National Geographic
Society. Retrieved 2017-06-26.
^ Glossary of Meteorology (2009). Rainy season. Archived 2009-02-15 at
the Wayback Machine. American Meteorological Society. Retrieved on
^ Michael Pidwirny (2008). CHAPTER 9: Introduction to the Biosphere.
PhysicalGeography.net. Retrieved on 2008-12-27.
^ "Updated world Koppen-Geiger climate classification map"
^ Elisabeth M. Benders-Hyde (2003). World Climates. Blue Planet
Biomes. Retrieved on 2008-12-27.
^ J . S. 0guntoyinbo and F. 0. Akintola (1983). Rainstorm
characteristics affecting water availability for agriculture. Archived
2009-02-05 at the Wayback Machine. IAHS Publication Number 140.
Retrieved on 2008-12-27
^ Arnold, David. "Illusory Riches: Representations of the Tropical
World, 1840-1950", p. 6. Journal of Tropical Geography
^ a b Arnold, David. "Illusory Riches: Representations of the Tropical
World, 1840-1950", p. 7. Journal of Tropical Geography
^ Arnold, David. "Illusory Riches: Representations of the Tropical
World, 1840-1950", p. 13. Journal of Tropical Geography
Wikimedia Commons has media related to Tropics.
(bilingual web site English/German with a lot of information and
extracts from novels, short stories, essays, etc. written by
explorers, conquerors and writers since the discovery of the so-called