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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 °C (64 °F). In tropical climates there are often only two seasons: a wet season and a dry season, which in the case of Aw/As climates, the wet season may run from the high-sun half of the year (Which runs from April to September in the Northern Hemisphere, and from October to March in the Southern Hemisphere) or the low-sun half of the year (Which runs from October to March in the Northern Hemisphere, and from April to September in the Southern Hemisphere). Tropical climates are typically frost-free, and changes in the solar angle are small. In tropical climates, the temperature remains relatively constant (hot) throughout the year. Sunlight is intense.

Sub types

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Within the tropical climate zone there are three distinct varieties based on precipitation:

hi

Tropical monsoon climate

This type of climate results from the monsoon winds which change direction according to the seasons. In this type of tropical climate, there is a short but distinct dry season. Thus, this zone falls under the influence of the Intertropical Convergence Zone at the time of high sun (summer) and under the influence of the drier Trade Winds at the time of low sun (winter). This climate has a driest month (which nearly always occurs at or soon after the "winter" solstice for that side of the equator) with rainfall less than 60 mm, but at least ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$.

Cities featuring a Tropical monsoon climate

Tropical wet and dry or savanna climate

Aw climates have a pronounced dry season, with the driest month having precipitation less than 60 mm and less than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$. In the Aw tropical climate the dry season is often several months and can be severe, with most plant and animal life adapting to drought conditions for several months. Aw climates often (but not always as in Africa) occur in higher tropical latitudes, between 15 and 20 north and south. Climates often feature tree-studded grasslands, rather than thick jungle. It is this widespread occurrence of tall, coarse grass (called savanna) which has led to Aw climates often being referred to as tropical savanna. However, there is some doubt whether tropical grasslands are climatically induced. Additionally, pure savannas, without trees, are the exception rather than the rule. It is one of the two varieties of the tropical savanna climates, along with As, with the main difference being that the wet-season in Aw climates usually run in the high-sun months of the year, which runs from April to September in the northern hemisphere, and from October to March in the southern hemisphere.

This type of tropical climate occurs in northern Australia, across the Sudan and eastern Africa, and parts south-central Brazil and adjacent parts of Bolivia and Paraguay and western Madagascar in the southern hemisphere. In the northern hemisphere tropical savanna climate occurs north of the Amazon in Venezuela and Colombia, as well as parts of western Central America, western Cuba, and the extreme southern part of Florida in the United States.

Cities featuring a Tropical savanna climate

Sometimes As is used in place of Aw if the dry season occurs during the high-sun half of the year, which runs from April to September in the northern hemisphere, and from October to March in the southern hemisphere. This is the case in parts of Hawaii, parts of the Caribbean, East Africa, areas of South Asia around the Laccadive Sea and the Brazilian Northeastern Coast. In most places that have tropical wet and dry climates (Aw), however, the dry season occurs during the time of low-sun half of the year, which runs in opposition to As climates.

Examples

• Chennai, India (As)
• Mombasa, Kenya (As)
• Monte Cristi, Dominican Republic (As)
• Natal, Brazil (As)
• Trincomalee, Sri Lanka (As)

Intertropical Convergence Zone

Because of the effect of sun angle on climate most areas within the tropics are hot year-round, with diurnal variations in temperature exceeding seasonal variations. Seasonal variations in tropical climate are dominated by changes in precipitation, which are in turn largely influenced by the tropical rain belt or Intertropical Convergence Zone (ITCZ), a portion of the Hadley cell. The ITCZ is shown, for July average, in the graphic. Areas of ascending air have heavy rainfall; areas of descending air are dry. The ITCZ somewhat follows the solar equator throughout the year, but with geographical variations, and in some areas (India) is heavily influenced by local large-scale monsoons.

See also

• Tropical ecology
• Tropical vegetation
• Tropic

References

1. ^ Peel, M.C.; Finlayson, B.L.; McMahon, T.A. (2007). "Updated world map of the Koppen-Geiger climate classification" (PDF). Hydrology and Earth System Sciences. 11: 1633–1644.
2. ^ Wood, Eric F.; Berg, Alexis; Noemi Vergopolan; McVicar, Tim R.; Zimmermann, Niklaus E.; Beck, Hylke E. (2018-10-30). "Present and future Köppen-Geiger climate classification maps at 1-km resolution". Scientific Data. 5: 180214. doi:10.1038/sdata.2018.214. ISSN 2052-4463.
3. Linacre, Edward; Bart Geerts (1997). Climates and Weather Explained. London: Routledge. p. 379. ISBN 978-0-415-12519-2.
4. McKnight, Tom L; Hess, Darrel (2000). "Climate Zones and Types". Physical Geography: A Landscape Appreciation. Upper Saddle River, NJ: Prentice Hall. ISBN 978-0-13-020263-5.

External links

• Media related to Tropical climate at Wikimedia Commons

• Climate
• Köppen climate classifications
• Atmospheric dynamics
• Tropics