Tropical monsoon climate

An area of tropical monsoon climate (occasionally known as a tropical wet climate or a tropical monsoon and trade-wind littoral 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 °F) in every month of the year and a dry season.[1]^:200–1 Tropical monsoon climates 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, however, has its driest month seeing on average less than 60 mm, but more than ${\textstyle 100-\left({\frac {Total\ Annual\ Precipitation\ (mm)}{25}}\right)}$.[1] This latter fact is in direct contrast to a tropical savanna climate, whose driest month sees 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 see more rainfall than a tropical savanna climate or have less pronounced dry seasons. Additionally, a tropical monsoon climate tends to see less variance in temperatures during the course of the year than a tropical savanna climate. This climate has a driest month which nearly always occurs at or soon after the winter solstice for that side of the equator.[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. However, unlike most tropical savanna climates, a sizeable amount of precipitation also falls during the dry season(s). 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. However, 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.

Distribution

Tropical monsoon climate is mainly found between 5° to 30° latitudes in the Southern and South-Eastern part of Asia. Tropical monsoon are most commonly found in Africa (West and Central Africa), Asia (South and Southeast Asia), South 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 towards 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 tradewind coasts.

Cities with a tropical monsoon climate

Bandung, Indonesia Bata, Equatorial Guinea Batticaloa, Sri Lanka Cairns, Queensland, Australia Calamba, Philippines Chittagong, Bangladesh Conakry, Guinea Da Nang, Vietnam Douala, Cameroon Freetown, Sierra Leone Hat Yai, Thailand Jakarta, Indonesia Kochi, Kerala, India

Malé, Maldives Miami, Florida, United States Monrovia, Liberia Nakhon Si Thammarat, Thailand Port Harcourt, Nigeria Recife, Pernambuco, Brazil San Juan, Puerto Rico Santo Domingo, Dominican Republic Semarang, Indonesia Taitung, Taiwan Thiruvananthapuram, Kerala, India Villahermosa, Mexico Yangon, Myanmar

Charts of selected cities

Chittagong
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
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

Manaus
Climate chart (explanation)
J F M A M J J A S O N D     260     31 23     288     30 23     314     31 23     300     31 23     256     31 23     114     31 23     88     31 23     58     33 23     83     33 24     126     33 24     183     32 24     217     31 24 Average max. and min. temperatures in °C Precipitation totals in mm Source: WMO[4] HK[5]
Imperial conversion J F M A M J J A S O N D     10     87 74     11     87 74     12     87 74     12     87 74     10     87 74     4.5     88 73     3.4     88 73     2.3     91 73     3.3     91 74     4.9     91 75     7.2     90 75     8.5     88 74 Average max. and min. temperatures in °F Precipitation totals in inches

Miami
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[6]
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

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. "Weather Information for Manaus". World Meteorological Organization. Retrieved 25 June 2018.
5. "Climatological Information for Manaus, Brazil". Hong Kong Observatory. 20 December 2012. Retrieved 25 June 2018.
6. "Weather Information for Miami, Florida". World Meteorological Organization. Retrieved 25 June 2018.