# Tropical savanna climate

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Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds to the Köppen climate classification categories Aw (for a dry winter) and As (for a dry summer). The driest month has less than 60 mm (2.4 in) of precipitation and also less than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$ of precipitation. [1] :200–1

## Contents

This latter fact is in direct contrast to a tropical monsoon climate, whose driest month sees less than 60 mm (2.4 in) of precipitation but has more than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$ of precipitation. In essence, a tropical savanna climate tends to either see less rainfall than a tropical monsoon climate or have more pronounced dry season(s).

In tropical savanna climates, the dry season can become severe, and often drought conditions prevail during the course of the year. Tropical savanna 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 and As 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.

## Versions

There are generally four types of tropical savanna climates:

• Distinct wet and dry seasons of relatively equal duration. Most of the region's annual rainfall is experienced during the wet season and very little precipitation falls during the dry season.
• A lengthy dry season and a relatively short wet season. This version features seven or more dry season months and five or fewer wet season months. There are variations within this version:
• On one extreme, the region receives just enough precipitation during the short wet season to preclude it from a semi-arid climate classification. This drier variation of the tropical savanna climate is typically found adjacent to regions with semi-arid climates.
• On the other extreme, the climate features a lengthy dry season followed by a short but extremely rainy wet season. However, regions with this variation of the climate do not experience enough rainfall during the wet season to qualify as a tropical monsoon climate.
• A lengthy wet season and a relatively short dry season. This version features seven or more wet season months and five or fewer dry season months. This version's precipitation pattern is similar to precipitation patterns observed in some tropical monsoon climates but does not experience enough rainfall during the wet season to be classified as such.
• A dry season with a noticeable amount of rainfall followed by a rainy wet season. In essence, this version mimics the precipitation patterns more commonly found in a tropical monsoon climate, but do not receive enough precipitation during either the dry season or the year to be classified as such.

## Distribution

Tropical savanna climates are most commonly found in Africa, Asia and South America. The climate is also prevalent in sections of Central America, northern Australia, the Pacific Islands, in sections of North America and some islands in the Caribbean. Most places that have this climate are found at the outer margins of the tropical zone, but occasionally an inner-tropical location (e.g., San Marcos, Antioquia, Colombia) also qualifies. Similarly, the Caribbean coast, eastward from the Gulf of Urabá on the ColombiaPanamá border to the Orinoco river delta, on the Atlantic Ocean (ca. 4,000 km (2,485 mi)), have long dry periods (the extreme is the BSh climate (see below), characterized by very low, unreliable precipitation, present, for instance, in extensive areas in the Guajira, and Coro, western Venezuela, the northernmost peninsulas in South America, which receive <300 mm (11.8 in) total annual precipitation, practically all in two or three months). This condition extends to the Lesser Antilles and Greater Antilles forming the Circumcaribbean dry belt. The length and severity of the dry season diminishes inland (southward); at the latitude of the Amazon river—which flows eastward, just south of the equatorial line—the climate is Af. East from the Andes, between the arid Caribbean and the ever-wet Amazon, are the Orinoco river Llanos or savannas, from where this climate takes its name.

Sometimes As is used in place of Aw if the dry season occurs during the time of higher sun and longer days, such as in Honolulu, Hawaii. [2] This may also be due to a rain shadow effect that cuts off summer precipitation in a tropical area. This is the case in East Africa (Mombasa, Kenya, Somalia), Sri Lanka (Trincomalee) and coastal regions of Northeastern Brazil (from Fortaleza through Natal to Maceió), for instance. The difference between 'summer' and 'winter' in such locations is usually so slight that a distinction between an As and Aw climate is a quibble. In most places that have tropical wet and dry climates, however, the dry season occurs during the time of lower sun and shorter days because of reduction of or lack of convection, which in turn is due to the meridional shifts of the Intertropical Convergence Zone during the entire course of the year.

## Some examples of tropical savanna climates

Banjul, The Gambia
Climate chart (explanation)
 J F M A M J J A S O N D 0.5  3216 0  3417 0  3418 0  3319 1.3  3220 63  3223 232  3124 347  3023 255  3123 76  3222 1.6  3319 0.7  3216 Average max. and min. temperatures in °C Precipitation totals in mm Source: BBC Weather [3]
Monte Cristi, Dominican Republic
Climate chart (explanation)
 J F M A M J J A S O N D 74  2919 47  2920 48  3020 59  3121 60  3222 40  3323 22  3423 28  3423 35  3423 68  3322 108  3121 84  2920 Average max. and min. temperatures in °C Precipitation totals in mm Source: NOAA [4]
Brasília, Brazil
Climate chart (explanation)
 J F M A M J J A S O N D 241  2717 215  2717 189  2718 124  2717 39  2615 8.8  2513 12  2513 13  2715 52  2816 172  2817 238  2718 249  2618 Average max. and min. temperatures in °C Precipitation totals in mm Source: World Weather Information Service
Darwin, Australia
Climate chart (explanation)
 J F M A M J J A S O N D 466  3225 373  3225 335  3225 108  3324 25  3223 2.3  3120 1.2  3120 5.8  3220 18  3323 65  3425 137  3426 276  3326 Average max. and min. temperatures in °C Precipitation totals in mm Source: Australian Bureau of Meteorology
Bangkok, Thailand
Climate chart (explanation)
 J F M A M J J A S O N D 13  3323 20  3324 42  3426 91  3527 248  3426 157  3426 175  3326 219  3326 334  3325 292  3325 50  3224 6.3  3222 Average max. and min. temperatures in °C Precipitation totals in mm Source: Thai Meteorological Department [5]
Tegucigalpa, Honduras
Climate chart (explanation)
 J F M A M J J A S O N D 5.3  2614 4.7  2715 9.9  3016 43  3017 144  3018 159  2918 82  2818 89  2918 177  2918 109  2718 40  2616 9.9  2515 Average max. and min. temperatures in °C Precipitation totals in mm Source: WMO [6]

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The Coastal Venezuelan mangroves ecoregion covers the salt-water mangrove forests along the Caribbean Sea and Atlantic Ocean coast of Venezuela, from Cocinetas Basin to the edge of the Caño Manamo River and the Orinoco Delta in the east. It is one of the largest mangrove ecoregions in South America, with an area of 5,698 km2, and stretching across over 400 km of Venezuelan coastline.

The Trinidad and Tobago moist forests ecoregion covers most of Trinidad Island and Tobago Island near the coast of South America where the southeastern Caribbean Sea meets the Atlantic Ocean. Small portions of the islands around river estuaries and coastal lowlands are mangroves or dry forests. Species diversity is very high, in particular for plants and birds. Tobago, being much smaller, has fewer species.

## References

1. McKnight, Tom L; Hess, Darrel (2000). . . Upper Saddle River, New Jersey: Prentice Hall. ISBN   978-0-13-020263-5.
2. "Honolulu, Hawaii Köppen Climate Classification". Weatherbase.
3. "World Weather Information Service — Banjul" . Retrieved 3 March 2020.
4. "Climatological Data for The Period 1981–2010". Thai Meteorological Department. p. 16.