Tropical monsoon climate

An area of tropical monsoon climate (occasionally known as a sub-equatorial, tropical wet climate or a tropical monsoon and trade-wind littoral climate) is a tropical climate subtype that corresponds to the Köppen climate classification category Am. Tropical monsoon climates have monthly mean temperatures above 18 °C (64 °F) in every month of the year and a dry season.^{[1]: 200–1} The tropical monsoon climate is the intermediate climate between the wet Af (or tropical rainforest climate) and the drier Aw (or tropical savanna climate).

Worldwide zones of tropical monsoon climate (Am).

A tropical monsoon climate's driest month has on average less than 60 mm, but more than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$.^[1] This is in direct contrast to a tropical savanna climate, whose driest month has less than 60 mm of precipitation and also less than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$ of average monthly precipitation. In essence, a tropical monsoon climate tends to either have more rainfall than a tropical savanna climate or have less pronounced dry seasons. A tropical monsoon climate tends to vary less in temperature during a year than does a tropical savanna climate. This climate has the driest month, which nearly always occurs at or soon after the winter solstice.^[1]

Versions

There are generally two versions of a tropical monsoon climate:

• Less pronounced dry seasons. Regions with this variation of the tropical monsoon climate typically see copious amounts of rain during the wet season(s), usually in the form of frequent thunderstorms. Unlike most tropical savanna climates, a sizeable amount of precipitation also falls during the dry season(s), but not quite enough for a tropical rainforest classification. In essence, this version of the tropical monsoon climate generally has less pronounced dry seasons than tropical savanna climates.
• Extraordinarily rainy wet seasons and pronounced dry seasons. This variation features pronounced dry seasons similar in length and character to dry seasons observed in tropical savanna climates. This is followed by a sustained period (or sustained periods) of extraordinary rainfall. In some instances, up to (and sometimes in excess of) 1,000 mm of precipitation is observed per month for two or more consecutive months. Tropical savanna climates generally do not see this level of sustained rainfall.

Area

Magdalena River at Honda, Colombia.

Tropical monsoon are most commonly found in Africa (West and Central Africa), Asia (South and Southeast Asia), South America and Central America. This climate also occurs in sections of the Caribbean, North America, and northern Australia.

Factors

The major controlling factor over a tropical monsoon climate is its relationship to the monsoon circulation. The monsoon is a seasonal change in wind direction. In Asia, during the summer (or high-sun season) there is an onshore flow of air (air moving from ocean toward land). In the “winter” (or low-sun season) an offshore air flow (air moving from land toward water) is prevalent. The change in direction is due to the difference in the way water and land heat.

Changing pressure patterns that affect the seasonality of precipitation also occur in Africa, though it generally differs from the way it operates in Asia. During the high-sun season, the Intertropical Convergence Zone (ITCZ) induces rain. During the low-sun season, the subtropical high creates dry conditions. The monsoon climates of Africa, and the Americas for that matter, are typically located along trade wind coasts.

Countries and cities

Asia Chittagong, Bangladesh Sylhet, Bangladesh Sihanoukville, Cambodia Qionghai, China Wanning, China Kochi, Kerala, India Mangalore, Karnataka, India Thiruvananthapuram, Kerala, India Bandung, Indonesia Jakarta, Indonesia Makassar, Indonesia Chichijima, Japan Alor Setar, Kedah, Malaysia Langkawi, Malaysia Malé, Maldives Yangon, Myanmar Calamba, Philippines Manila, Philippines Quezon City, Philippines Batticaloa, Sri Lanka Kaohsiung, Taiwan Pingtung, Taiwan Taitung, Taiwan Hat Yai, Thailand Narathiwat, Thailand Pattani, Thailand Cà Mau, Vietnam Da Nang, Vietnam

Oceania Cairns, Queensland, Australia Christmas Island, Australia Saipan, Northern Mariana Islands Africa Douala, Cameroon Bata, Equatorial Guinea Conakry, Guinea Monrovia, Liberia Port Harcourt, Nigeria Freetown, Sierra Leone The Americas Recife, Pernambuco, Brazil Macapá, Amapá, Brazil Barrancabermeja, Colombia Villavicencio, Colombia Roseau, Dominica Santo Domingo, Dominican Republic Villahermosa, Mexico Nassau, The Bahamas Port of Spain, Trinidad and Tobago Miami, Florida, United States San Juan, Puerto Rico, United States

Select charts

Chittagong, Bangladesh
Climate chart (explanation)
J F M A M J J A S O N D     5     27 15     28     30 19     64     35 24     150     39 26     264     35 24     533     34 25     597     38 26     518     33 24     320     33 24     180     32 23     56     32 17     15     24 14 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: BBC[2]
Imperial conversion J F M A M J J A S O N D     0.2     81 59     1.1     86 66     2.5     95 75     5.9     102 79     10     95 75     21     93 77     24     100 79     20     91 75     13     91 75     7.1     90 73     2.2     90 63     0.6     75 57 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Conakry, Guinea
Climate chart (explanation)
J F M A M J J A S O N D     1     32 19     1     33 20     3     33 21     22     34 22     137     33 21     396     32 20     1130     30 20     1104     30 21     617     31 21     295     31 20     70     32 21     8     32 20 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: HK[3]
Imperial conversion J F M A M J J A S O N D     0     90 66     0     92 68     0.1     92 70     0.9     92 72     5.4     92 69     16     89 68     44     86 69     43     86 69     24     87 69     12     88 69     2.8     90 70     0.3     90 68 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Jakarta, Indonesia
Climate chart (explanation)
J F M A M J J A S O N D     363     31 24     323     31 24     191     32 25     153     32 25     110     33 25     75     33 25     66     32 24     53     33 25     61     33 25     111     33 25     124     32 25     196     31 25 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: BMKG[4]
Imperial conversion J F M A M J J A S O N D     14     87 76     13     87 76     7.5     89 76     6     90 77     4.3     91 77     3     91 77     2.6     90 76     2.1     91 76     2.4     91 76     4.4     91 77     4.9     90 77     7.7     89 76 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Miami, Florida, US
Climate chart (explanation)
J F M A M J J A S O N D     51     24 15     53     25 16     61     26 18     72     28 20     158     30 22     237     31 24     145     32 25     193     32 25     194     31 24     143     29 22     68     27 19     47     25 16 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: WMO[5]
Imperial conversion J F M A M J J A S O N D     2     75 59     2.1     76 60     2.4     79 64     2.9     82 68     6.2     85 72     9.3     88 75     5.7     89 76     7.6     89 77     7.6     88 76     5.6     85 72     2.7     80 67     1.8     77 62 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

See also

• Tropical climate
• Tropical rainforest climate
• Tropical savanna climate
• Köppen climate classification

References

1. McKnight, Tom L; Hess, Darrel (2000). "Climate Zones and Types". Physical Geography: A Landscape Appreciation. Upper Saddle River, New Jersey: Prentice Hall. ISBN 978-0-13-020263-5.
2. "Average Conditions - Chittagong, Bangladesh". BBC Weather. Archived from the original on 11 March 2006. Retrieved 25 June 2018.
3. "Climatological Normals of Conakry". Hong Kong Observatory. Retrieved 2014-02-12.
4. "Climatological Average of Kemayoran Meteorological Station for 1981–2010" (in Indonesian). Pondok Betung Climatological Station – Indonesian Bureau of Meteorology, Climatology, and Geophysics. Archived from the original on 21 April 2021. Retrieved 19 April 2021.
5. "Weather Information for Miami, Florida". World Meteorological Organization. Retrieved 25 June 2018.