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Worldwide zones of tropical monsoon climate (Am).

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 sub-type 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).

A tropical monsoon climate's driest month has on average less than 60 mm, but more than . [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 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 a 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 tradewind coasts.

Countries and cities

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
JFMAMJJASOND
 
 
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
JFMAMJJASOND
 
 
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
Miami, Florida, United States
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 [4]
Imperial conversion
JFMAMJJASOND
 
 
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

References

  1. ^ a b c 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 Miami, Florida". World Meteorological Organization. Retrieved 25 June 2018.