Tropics

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World map with the intertropical zone highlighted in crimson World map indicating tropics and subtropics.png
World map with the intertropical zone highlighted in crimson
Areas of the world with tropical climates. Koppen-Geiger Map A present.svg
Areas of the world with tropical climates.

The tropics are the region of the Earth surrounding the Equator. They are delimited in latitude by The Tropic of Cancer in the Northern Hemisphere at 23°26′12.5″ (or 23.4368°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′12.5″ (or 23.4368°) 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 a point directly overhead at least once during the solar year (which is a subsolar point) - thus the latitude of the tropics is roughly equal to the angle of the Earth's axial tilt.

Earth Third planet from the Sun in the Solar System

Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.

Equator Intersection of a spheres surface with the plane perpendicular to the spheres axis of rotation and midway between the poles

An equator of a rotating spheroid is its zeroth circle of latitude (parallel). It is the imaginary line on the spheroid's surface, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid's surface with the plane perpendicular to its axis of rotation and midway between its geographical poles.

Latitude The angle between zenith at a point and the plane of the equator

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 which ranges from 0° at the Equator to 90° at the poles. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth. On its own, the term latitude should be taken to be the geodetic latitude as defined below. Briefly, geodetic latitude at a point is the angle formed by the vector perpendicular to the ellipsoidal surface from that point, and the equatorial plane. Also defined are six auxiliary latitudes which are used in special applications.

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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.

Middle latitudes

The middle latitudes of Earth lie between 23°26'22" and 66°33'39" north, and between 23°26'22" and 66°33'39" south. They include Earth's subtropical temperate zones, which lie between the tropics and the polar circles. Weather fronts and extratropical cyclones are usually found in this area, as well as occasional tropical cyclones, which have traveled from their areas of formation closer to the Equator.

Polar regions of Earth regions around the Earths geographical poles

The polar regions, also called the frigid zones, of Earth are the regions of the planet that surround its geographical poles, lying within the polar circles. These high latitudes are dominated by Earth's polar ice caps: the northern resting on the Arctic Ocean and the southern on the continent of Antarctica.

The tropics comprise 40% of the Earth's surface area [1] and contain 36% of the Earth's landmass. [2] As of 2014, the region is home to 40% of the world population, and this figure is projected to reach 50% by the late 2030s. [3]

Landmass is a contiguous region of land surrounded by ocean.

World population The total number of living humans on Earth

In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7.6 billion people as of May 2018. It took over 200,000 years of human history for the world's population to reach 1 billion; and only 200 years more to reach 7 billion.

Seasons and climate

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 desert areas. Monthly zonal mean precipitation.png
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 desert areas.
Aerial view of Bora Bora, French Polynesia Bora Bora.jpg
Aerial view of Bora Bora, French Polynesia
Tropical sunset over the sea in Kota Kinabalu, Malaysia 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.

Tropical climate climate in the tropical region

A tropical climate in the Köppen climate classification is a non-arid climate in which all twelve months have mean temperatures of warmer than 18.4 °C (65.1 °F). In tropical climates there are often only two seasons: a wet season and a dry season. Tropical climates are frost-free, and changes in the solar angle are small. In tropical climates temperature remains relatively constant (hot) throughout the year. Sunlight is intense.

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. [4] Areas with wet seasons are disseminated across portions of the tropics and subtropics. [5] 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. [6] Tropical rainforests technically do not have dry or wet seasons, since their rainfall is equally distributed through the year. [7] 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; [8] typical vegetation in these areas ranges from moist seasonal tropical forests to savannahs.

Wet season yearly period of high rainfall, especially in the tropics

The monsoon season is the time of year when most of a region's average annual rainfall occurs. Generally the season lasts at least a month. The term "green season" is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the tropics and subtropics.

Subtropics

The subtropics are geographic and climate zones located roughly between the tropics at latitude 23.5° and temperate zones north and south of the Equator.

Köppen climate classification widely used climate classification system

The Köppen climate classification is one of the most widely used climate classification systems. It was first published by the Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, the climatologist Rudolf Geiger introduced some changes to the classification system, which is thus sometimes called the Köppen–Geiger climate classification system.

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. Soil nutrients 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. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature.

Summer one of the Earths four temperate seasons, occurring between spring and autumn

Summer is the hottest of the four temperate seasons, falling after spring and before autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice. The date of the beginning of summer varies according to climate, tradition, and culture. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, and vice versa.

Soil mixture of organic matter, minerals, gases, liquids, and organisms that together support life

Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions:

Malaria mosquito-transmitted disease

Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases it can cause yellow skin, seizures, coma, or death. Symptoms usually begin ten to fifteen days after being bitten by an infected mosquito. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria.

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.

Ecosystems

Coconut palms in the warm, tropical climate of northern Brazil Pajucara.jpg
Coconut palms in the warm, tropical climate of northern Brazil
Tropical forest near Fonds-Saint-Denis, Martinique Tropical forest.JPG
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 eastern 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

"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 geographer Pierre Gourou published Les Pays Tropicaux (The Tropical World, in English), in the late 1940s. [9]

Tropicality encompasses at least two contradictory imageries. One is that the tropics represent a Garden of Eden, a heaven on Earth; [10] 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. [10] Evidence suggests that over time the more primitive view of the tropics in popular literature has been supplanted by more nuanced interpretations that reflect historical changes in values associated with tropical culture and ecology, although some primitive associations are persistent. [11]

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 nature". [12]

See also

Related Research Articles

Geography of Nigeria

Nigeria is a country in West Africa. Nigeria shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in the north. Its coast lies on the Gulf of Guinea in the south and it borders Lake Chad to the northeast. Noted geographical features in Nigeria include the Adamawa highlands, Mambilla Plateau, Jos Plateau, Obudu Plateau, the Niger River, River Benue and Niger Delta.

Temperate climate hovers around the same temperature

In geography, the temperate or tepid climates of Earth occur in the middle latitudes, which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout the year and more distinct seasonal changes compared to tropical climates, where such variations are often small. They typically feature four distinct seasons, Summer the warmest, Autumn the transitioning season to Winter, the colder season, and Spring the transitioning season from winter back into summer. On the northern hemisphere the year starts with winter, transitions in the first halfyear trough spring into summer which is in mid-year, then at the second halfyear trough autumn into winter at year-end. On the southern hemisphere seasons are swapped with summer in between years and winter in mid-year.

Tropical and subtropical moist broadleaf forests biome

Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forests, are a tropical and subtropical forest habitat type defined by the World Wide Fund for Nature. The habitat type is sometimes known as jungle.

The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The tropical rain belt lies in the southern hemisphere roughly from October to March; during that time the northern tropics have a dry season with sparser precipitation, and days are typically sunny throughout. From April to September, the rain belt lies in the northern hemisphere, and the southern tropics have their dry season. Under the Köppen climate classification, for tropical climates, a dry season month is defined as a month when average precipitation is below 60 millimetres (2.4 in).

Rainfall and the tropical climate dominate the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year, roughly following the solar equator. The tropical rain belt is an area of active rain that is positioned mostly around the tropics. According to the website Journey North, the reason the rain belt is situated near the tropics can be attributed to the fact that most of the sun’s radiation is directed toward the equator, which is located in the middle of the tropics. This solar radiation generates large amounts of heat near the equator providing tropical regions with higher temperatures than most other regions on Earth.

Northern Australia Area

The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26° and all of the Northern Territory. Those local government areas of Western Australia and Queensland that lie partially in the north are included.

Climatic regions of India

India has a large variation in climate from region to region, due to its vast size. India experiences climate from four major climate groups. These can be further subdivided into seven climatic types. For ecological regions, see Ecoregions of India, for Regions see List of regions of India.

A tropical marine climate is a tropical climate that is primarily influenced by the ocean. It is usually experienced by islands and coastal areas 10° to 20° north and south of the equator. There are two main seasons in a tropical marine climate: the wet season and the dry season. The annual rainfall is 1000 to over 1500 mm. The temperature ranges from 20 °C to 35 °C. The trade winds blow all year round and are moist, as they pass over warm seas. These climatic conditions are found, for example, across the Caribbean; the eastern coasts of Brazil, Madagascar and Queensland; and many islands in tropical waters.

Geographical zone Major regions of the Earths surface demarcated by latitude

The five main latitude regions of the Earth's surface comprise geographical zones, divided by the major circles of latitude. The differences between them relate to climate. They are as follows:

  1. The North frigid zone, between the Arctic Circle 66.5° N and the North Pole 90° N. Covers 4.12% of Earth's surface.
  2. The North temperate zone, between the Tropic of Cancer 23.5° N and the Arctic Circle 66.5° N. Covers 25.99% of Earth's surface.
  3. The Torrid zone, between the Tropic of Cancer 23.5° N and the Tropic of Capricorn 23.5° S. Covers 39.78% of Earth's surface.
  4. The South temperate zone, between the Tropic of Capricorn 23.5° S and the Antarctic Circle 66.5° S. Covers 25.99% of Earth's surface.
  5. The South frigid zone, from Antarctic Circle 66.5° S and the South Pole 90° S. Covers 4.12% of Earth's surface.
Holdridge life zones

The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967. It is a relatively simple system based on few empirical data, giving objective mapping criteria. A basic assumption of the system is that both soil and climax vegetation can be mapped once the climate is known.

Paleotropical Kingdom

The Paleotropical Kingdom (Paleotropis) is a floristic kingdom comprising tropical areas of Africa, Asia and Oceania, as proposed by Ronald Good and Armen Takhtajan. Part of its flora, inherited from the ancient supercontinent of Gondwana or exchanged later, is shared with the Neotropical Kingdom, comprising tropical areas of Central and South America. Moreover, the Paleotropical flora influenced the tropical flora of the Australian Kingdom. The Paleotropical Kingdom is subdivided into five floristic subkingdoms according to Takhtajan and about 13 floristic regions. In this article the floristic subkingdoms and regions are given as delineated by Takhtajan.

Tropical savanna climate

Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds to the Köppen climate classification categories "Aw" and "As". Tropical savanna climates have monthly mean temperatures above 18 °C (64 °F) in every month of the year and typically a pronounced dry season, with the driest month having less than 60 mm of precipitation and also less than 100 – [total annual precipitation {mm}/25] of precipitation.

Tropical rainforest climate

A tropical rainforest climate is a tropical climate usually found within 10 to 15 degrees latitude of the equator, and has at least 60 mm of rainfall every month of the year. Regions with this climate are typically designated Af by the Köppen climate classification. A tropical rainforest climate is typically hot and wet.

Tropical horticulture horticulture in the tropics

Tropical horticulture is a branch of horticulture that studies and cultivates plants in the tropics, i.e., the equatorial regions of the world. The field is sometimes known by the portmanteau "TropHort".

Tropical monsoon climate

A area of tropical monsoon climate is a type of climate that corresponds to the Köppen climate classification category "Am". Tropical monsoon climates have monthly mean temperatures above 18 °C (64.4 °F) in every month of the year. Tropical monsoon climates is the intermediate climate between the wet Af and Aw.

Seasonal tropical forest

Seasonal 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 forest is classified under the Walter system as (ii) tropical climate with high overall rainfall concentrated in the summer wet season and cooler “winter” dry season: representing a range of habitats influenced by monsoon (Am) or tropical wet savannah (Aw) climates. Drier forests in the Aw climate zone are typically deciduous and placed in the Tropical dry forest biome: with further transitional zones (ecotones) of savannah woodland then tropical and subtropical grasslands, savannas, and shrublands.

References

  1. "How much land is in the tropics?". God Plays Dice. 2007-12-04. Retrieved 2017-06-26.
  2. "tropics". National Geographic Encyclopedia. National Geographic Society. Retrieved 2017-06-26.
  3. "Expanding tropics will play greater global role, report predicts". Science Magazine. 29 June 2014.
  4. Glossary of Meteorology (2009). Rainy season. Archived 2009-02-15 at the Wayback Machine American Meteorological Society. Retrieved on 2008-12-27.
  5. Michael Pidwirny (2008). CHAPTER 9: Introduction to the Biosphere. PhysicalGeography.net. Retrieved on 2008-12-27.
  6. "Updated world Koppen-Geiger climate classification map" (PDF).
  7. Elisabeth M. Benders-Hyde (2003). World Climates. Blue Planet Biomes. Retrieved on 2008-12-27.
  8. 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
  9. Arnold, David. "Illusory Riches: Representations of the Tropical World, 1840-1950", p. 6. Journal of Tropical Geography
  10. 1 2 Arnold, David. "Illusory Riches: Representations of the Tropical World, 1840-1950", p. 7. Journal of Tropical Geography
  11. Menadue, Christopher B. (2017-05-30). "Trysts Tropiques: The Torrid Jungles of Science Fiction". eTropic: electronic journal of studies in the tropics. 16 (1). doi:10.25120/etropic.16.1.2017.3570. ISSN   1448-2940.
  12. Arnold, David. "Illusory Riches: Representations of the Tropical World, 1840-1950", p. 13. Journal of Tropical Geography