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The tropics are the region of
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continent A continent is one of several large landmasses. Generally identified by con ...

Earth
surrounding the
Equator The Earth's equator is an imaginary planetary line that is about long in circumference. The equator divides the planet into the Northern Hemisphere and Southern Hemisphere and is located at 0 degrees latitude In geography, latitude is ...

Equator
. They are delimited in
latitude In geography, latitude is a geographic coordinate that specifies the north– south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. L ...

latitude
by the
Tropic of Cancer The Tropic of Cancer, which is also referred to as the Northern Tropic, is the most northerly circle of latitude In geography, latitude is a geographic coordinate that specifies the north– south position of a point on the Earth's surface ...

Tropic of Cancer
in the
Northern Hemisphere The Northern Hemisphere is the half of Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continent A continent is one of s ...

Northern Hemisphere
at N and the
Tropic of Capricorn The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point at the December (or southern) solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reaches ...
in the
Southern Hemisphere The Southern Hemisphere is the half (Hemispheres of Earth, hemisphere) of Earth that is south of the Equator. It contains all or parts of five continents (Antarctica, Australia (continent), Australia, about 90% of South America, one third of A ...

Southern Hemisphere
at S; these latitudes correspond to the
axial tilt In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses mat ...
of the Earth. The tropics are also referred to as the tropical zone and the torrid zone (see
geographical zone The five main latitude In geography, latitude is a geographic coordinate that specifies the north– south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (Nor ...
). The tropics include everywhere on Earth which is a
subsolar point The subsolar point on a planet is the point at which its sun is perceived to be directly overhead (at the zenith); that is, where the sun's rays strike the planet exactly perpendicular In elementary geometry, the property of being perpendicu ...

subsolar point
(the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
is
directly overhead
directly overhead
) at least once during the
solar year A tropical year (also known as a solar year) is the time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparently irreversible process, irreversible succession from the past, ...
. Thus the maximum latitudes of the tropics have the same value positive and negative. Likewise, they approximate, due to the earth not being a perfect sphere, the "angle" of the
Earth's axial tilt
Earth's axial tilt
. The "angle" itself is not perfectly fixed due chiefly to the influence of the moon, but the limits of tropics are a geographic convention, being an averaged form, and the variance is very small. In terms of climate, the tropics receive sunlight that is more direct than the rest of Earth and are generally hotter and wetter. The word "tropical" sometimes refers to this sort of climate rather than to the geographical zone. The tropical zone includes deserts and snow-capped mountains, which are not tropical in the climatic sense. The tropics are distinguished from the other climatic and biomatic regions of Earth, which are the
middle latitudes The middle latitudes (also called the mid-latitudes, sometimes midlatitudes, or moderate latitudes) are a spatial region on Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of E ...
and the
polar regions The polar regions, also called the frigid zones, of Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continent A continent ...
on either side of the equatorial zone. The tropics constitute 40% of Earth's surface area and contain 36% of Earth's
landmass A landmass, or land mass, is a large region or area Area is the quantity that expresses the extent of a two-dimensional region, shape, or planar lamina, in the plane. Surface area is its analog on the two-dimensional surface of a ...
. , the region was home to 40% of the world's
population In biology, a population is a number of all the organisms of the same group or species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiv ...

population
, and this figure was then projected to reach 50% by 2050.


Etymology

The word "tropic" comes from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages () ...
τροπή (''tropē''), meaning "to turn" or "change direction".


Seasons and climate

,
French Polynesia )Territorial motto: ( en, "Great Tahiti of the Golden Haze") , anthem = "La Marseillaise" , song_type = Territorial anthem , song = "Ia Ora 'O Tahiti Nui" , image_map = French Polynesia on the globe (French Polynesia centered).svg , map_alt ...
Tropical sunset over the sea in [ File:Kota_Kinabalu_by_Dale_Preston.jpg.html" ;"title="ota Kinabalu">File:Kota Kinabalu by Dale Preston.jpg">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 vegetation. 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 The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones located to the north and south of the tropics, Torrid Zone. Geographically part of the Geographical zone#Temperate zones, ...

subtropics
. Under the
Köppen climate classification The Köppen climate classification is one of the most widely used climate classification 350px, Leslie Holdridge's Life Zone Classification system is essentially a climate classification scheme. Climate classification is a way of categorizing th ...
, for
tropical climate Tropical climate is one of the five major climate groups in the Köppen climate classification The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatolo ...
s, a wet-season month is defined as a month where average precipitation is or more. Some areas with pronounced rainy seasons see a break in rainfall during mid-season when the intertropical convergence zone or
monsoon trough The monsoon trough is a portion of the Intertropical Convergence Zone in the Western Pacific,Bin WangThe Asian Monsoon.Retrieved 2008-05-03. as depicted by a line on a weather map showing the locations of minimum sea level pressure, and as such ...
moves poleward of their location during the middle of the warm season;J . S. 0guntoyinbo and F. 0. Akintola (1983)
Rainstorm characteristics affecting water availability for agriculture.
IAHS Publication Number 140. Retrieved on 2008-12-27
typical vegetation in these areas ranges from moist
seasonal tropical forestSeasonal tropical forest, also known as moist deciduous, semi-evergreen seasonal, tropical mixed or monsoon forests, typically contain a range of tree species: only some of which drop some or all of their leaves during the dry season. This tropical f ...
s to
savannah A savanna or savannah is a mixed woodland-grassland ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient light to reach the ground to support ...

savannah
s. When the wet season occurs during the warm season, or
summer Summer is the hottest of the four temperate In geography, the temperate climates of Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land ...

summer
,
precipitation In meteorology Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant p ...
falls mainly during the late afternoon and early evening hours. The wet season is a time when
air quality Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gas ...
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.
Soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere ...

Soil
nutrients diminish and erosion increases. The incidence of
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for ...

malaria
increases in areas where the rainy season coincides with high temperatures. Animals have adaptation and survival strategies for the wetter regime. 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 The Köppen climate classification is one of the most widely used climate classification 350px, Leslie Holdridge's Life Zone Classification system is essentially a climate classification scheme. Climate classification is a way of categorizing th ...
, much of the area within the geographical tropics is classed not as "tropical" but as "dry" (
arid A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development Development or developing may refer to: Arts *Development hell, when a project is stuck in de ...
or
semi-arid A semi-arid climate, semi-desert climate, or steppe climate is the climate Climate is the long-term average of weather, typically averaged over a period of 30 years. More rigorously, it is the mean and variability of meteorological variables ove ...
), including the
Sahara Desert The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the African continent. With an area of , it is the largest hot desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty ...

Sahara Desert
, the Atacama Desert and
Australian Outback The Outback is a vast, sparsely populated area of Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the isl ...
. Also, there are
alpine tundra Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, ...
and snow-capped peaks, including
Mauna Kea Mauna Kea ( or , ) is a Volcano#Dormant, dormant volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in the state of Hawaii and List of islands by highest p ...

Mauna Kea
,
Mount Kilimanjaro Mount Kilimanjaro () is a Volcano#Dormant, dormant volcano in Tanzania. It has three volcanic cones: Kibo, Mawenzi, and Shira. It is the highest African mountains, mountain in Africa and the highest single free-standing mountain in the world ...

Mount Kilimanjaro
,
Puncak Jaya Puncak Jaya (; literally Glorious Peak) or Carstensz Pyramid, Mount Jayawijaya or Mount Carstensz is the highest mountain in Indonesia Indonesia ( ), officially the Republic of Indonesia ( id, Republik Indonesia, links=yes ), is a countr ...
and the
Andes The Andes, Andes Mountains or Andean Mountains ( es, Cordillera de los Andes) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of Sout ...
as far south as the northernmost parts of
Chile Chile, officially the Republic of Chile, is a country in the western part of South America South America is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention ra ...
and
Perú , , image_flag = Flag_of_Peru.svg , image_coat = Escudo_nacional_del_Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto ...
.


Ecosystems

Tropical plants Tropical vegetation is any vegetation in tropical latitudes. Plant life that occurs in climates that are warm year-round is in general more biologically diverse that in other latitudes. Some tropical areas may receive abundant rain the whole yea ...
and animals are those species native to the tropics. Tropical ecosystems may consist of
tropical rainforest File:Koppen-Geiger Map Af present.svg, upright=1.8, Tropical rainforest climate zones (Af). Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average p ...

tropical rainforest
s, seasonal tropical forests, dry (often deciduous) forests, spiny forests,
desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates">Rub'_al_Khali.html" ;"title="Sand dunes in the Rub' al Khali">Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab ...
and other habitat types. There are often significant areas of
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near t ...
, and species
endemism Endemism is the state of a species being native to a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...
present, particularly in rainforests and seasonal forests. Some examples of important biodiversity and high endemism ecosystems are
El Yunque National Forest El Yunque National Forest ( es, Bosque Nacional El Yunque), formerly known as the Caribbean National Forest (or ''Bosque Nacional del Caribe''), is a forest located in northeastern Puerto Rico. It is the only tropical rainforest in the United Stat ...
in
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico) is a Caribbean island and Unincorporated t ...

Puerto Rico
,
Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in Central America, bordered by Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southea ...
n and
Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in the Central American isthmus, bordered by Honduras to the northwest, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean The P ...

Nicaragua
n rainforests,
Amazon Rainforest The Amazon rainforest, alternatively, the Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest, ...

Amazon Rainforest
territories of several
South America South America is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven regions are commonly regarded as continents. Ordered fr ...

South America
n countries,
Madagascar dry deciduous forests The Madagascar dry deciduous forests represent a tropical and subtropical dry broadleaf forests, tropical dry forest ecoregion situated in the western and northern part of Madagascar. The area has high numbers of Endemism, endemic plant and animal ...
, the
Waterberg Biosphere The Waterberg ( nso, Thaba Meetse) is a mountainous massif In geology, a massif ( or ) is a section of a planet's Crust (geology), crust that is demarcated by geologic fault, faults or Lithospheric flexure, flexures. In the Plate tectonics, ...
of
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. With over Demographics of South Africa, 59 million people, it is the world's List of countries by population, 23rd-most populous nation a ...

South Africa
, and eastern
Madagascar Madagascar (; mg, Madagasikara), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), and previously known as the Malagasy Republic, is an island country in the Indian Ocean, a ...

Madagascar
rainforests. Often the soils of tropical forests are low in
nutrient A nutrient is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and ta ...
content, making them quite vulnerable to
slash-and-burn Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating ...
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...
techniques, which are sometimes an element of
shifting cultivation Shifting cultivation is an agricultural Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated ...

shifting cultivation
agricultural systems. In
biogeography Biogeography is the study of the distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological community (ecology), communities often vary in a regular f ...
, the tropics are divided into
Paleotropics in Burkina Faso '' in the Namib Desert ''Image:Nepenthes villosa.jpg, ''Nepenthes villosa''The Paleotropical Kingdom (Paleotropis) is a floristic kingdom comprising tropical areas of Africa, Asia and Oceania (excluding Australia and New Zealand), a ...
(Africa, Asia and Australia) and
Neotropics The Neotropical realm is one of the eight biogeographic realm A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided ...
(Caribbean, Central America, and South America). Together, they are sometimes referred to as the Pantropic. The system of
biogeographic realm A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into ecoregion An ecoregion (ecological region) or ecozone (ec ...
s differs somewhat; the
Neotropical realm The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical The tropics are the region of Earth surrounding the Equator. They are delimited in latitude by the T ...
includes both the Neotropics and temperate South America, and the Paleotropics correspond to the
Afrotropical The Afrotropical realm is one of Earth's eight biogeographic realms. It includes Africa south of the Sahara, Sahara Desert, the majority of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the ...
,
Indomalayan The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South Asia, South and Southeast Asia and into the southern parts of East Asia. Also called the Oriental realm by biogeography, biogeographers, Indomalaya s ...
,
Oceanian Oceania (, , ) is a Region, geographic region that includes Australasia, Melanesia, Micronesia and Polynesia. Spanning the eastern hemisphere, Eastern and Western Hemispheres, Oceania has a land area of and a population of over 41 million. Wh ...

Oceanian
, and tropical
Australasian realm Image:Ecozone Australasia.svg, 320px, The Australasian realm The Australasian realm is a biogeographic realm that is coincident, but not synonymous (by some definitions), with the geography, geographical region of Australasia. The realm includes Au ...
s.


Tropicality

Tropicality refers to the image that people from outside the tropics have of the region, ranging from critical to verging on fetishism. The idea of tropicality gained renewed interest in geographical discourse when French geographer
Pierre Gourou Pierre Gourou (31 August 1900 – 13 May 1999) was a French geographer. In 1984, he received the Patron's Medal from the Royal Geographical Society. Further reading

* Paul Claval: ''Pierre Gourou 1900–1999'', in ''Geographers: Biobibliog ...
published ''Les Pays Tropicaux'' (''The Tropical World'' in English), in the late 1940s. Tropicality encompassed two images. One, is that the tropics represent a '
Garden of Eden The Garden of Eden ( he, גַּן־עֵדֶן – ''gan-ʿḖḏen'') or Garden of God ( he, גַן־יְהוָה – ''gan- Yhwh''), also called the Terrestrial Paradise, is the biblical Paradise described in Genesis 2-3 and Ezekiel 28 and 3 ...

Garden of Eden
', a heaven on Earth, a land of rich
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near t ...
or a tropical paradise.Arnold, David. "Illusory Riches: Representations of the Tropical World, 1840-1950", p. 7. Journal of Tropical Geography The alternative is that the tropics consist of wild, unconquerable nature. The latter view was often discussed in old Western literature more so than the first. Evidence suggests over time that the view of the tropics as such in popular literature has been supplanted by more well-rounded and sophisticated interpretations. Western scholars tried to theorise why tropical areas were relatively more inhospitable to human civilisations than colder regions of the Northern Hemisphere. A popular explanation focused on the differences in climate. Tropical jungles and rainforests have much more humid and hotter weather than colder and drier temperaments of the Northern Hemisphere. This theme led some scholars to suggest that humid hot climates correlate to human populations lacking control over nature e.g. 'the wild Amazonian rainforests'.Arnold, David. "Illusory Riches: Representations of the Tropical World, 1840-1950", p. 13. Journal of Tropical Geography


See also

*
Hardiness zone Global Plant Hardiness Zones, 250px A hardiness zone is a geographic area defined to encompass a certain range of climatic conditions relevant to plant growth and survival. The original and most widely used system, developed by the United States ...
*
Subtropics The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones located to the north and south of the tropics, Torrid Zone. Geographically part of the Geographical zone#Temperate zones, ...

Subtropics
*
Tropical ecology Tropical ecology is the study of the relationships between the biotic and abiotic components of the tropics, or the area of the Earth that lies between the Tropic of Cancer and the Tropic of Capricorn (23.4378° N and 23.4378° S, respectively). The ...
*
Tropical marine climate A tropical marine climate is a tropical climate Tropical climate is one of the five major climate groups in the Köppen climate classification. Tropical climates are characterized by monthly average temperatures of 18 ℃ (64.4 ℉) or h ...
*
Tropical year A tropical year (also known as a solar year) is the time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparently irreversible process, irreversible succession from the past, ...


References


External links

{{Authority control Seasons