Tropical savanna climate

Worldwide zones of Tropical savanna climate (Aw/As)

Tropical savanna climate or tropical wet and dry climate is a tropical climate sub-type 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 mm of precipitation.[1]: 200–1 

This latter fact is in a direct contrast to a tropical monsoon climate, whose driest month sees less than 60 mm (2.4 in) of precipitation but has more than of precipitation. In essence, a tropical savanna climate tends to either see less overall rainfall than a tropical monsoon climate or have more pronounced dry season(s). It is impossible for a tropical savanna climate to have more than 2,500 mm (98 in) as such would result in a negative value in that equation.

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 due to its dryness, 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 the 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

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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 more 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 hot semi-arid (BSh) climates, such as seen in places like India, the Sahel region in Africa and Brazil.
    • 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 (Am). These can be found near tropical monsoon climates such as in Asia, Africa and the Americas.
  • A lengthy, moderately 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 (as well as subhumid temperate climates farther poleward) but does not experience enough rainfall during the wet season to be classified as such, while the rainfall in the dry season is just low enough to preclude a tropical rainforest climate (Af) and temperatures in the winter months are warm enough to preclude a humid subtropical climate (Cwa) or subtropical highland climate (Cwb) classification. This is often found near the poleward margins of the tropical savanna climates.
  • 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

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Dry forest in Thailand
Savanna in South Sudan

Tropical savanna climates are most commonly found in Africa, Asia, Central America, and South America. The climate is also prevalent in sections of northern Australia, the Pacific Islands, in extreme southern North America in south Florida, 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. This is typically due to a rain shadow effect that cuts off ITCZ-triggered summer precipitation in a tropical area while winter precipitation remains sufficient to preclude a hot semi-arid climate (BSh) and temperatures in the summer months are warm enough to preclude a Mediterranean climate (Csa/Csb) classification. This is the case East Africa (Mombasa, Kenya, Somalia), Sri Lanka (Trincomalee) and coastal regions of Northeastern Brazil (from São Luís[2] through Natal to Maceió), for instance. The difference between "summer" and "winter" in such tropical locations is usually so slight that a distinction between an As and Aw climate is trivial. 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, based on which hemisphere the location sits.

Cities with a tropical savanna climate

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Some examples of tropical savanna climates

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Banjul, The Gambia
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
0.5
 
 
32
16
 
 
0
 
 
34
17
 
 
0
 
 
34
18
 
 
0
 
 
33
19
 
 
1.3
 
 
32
20
 
 
63
 
 
32
23
 
 
232
 
 
31
24
 
 
347
 
 
30
23
 
 
255
 
 
31
23
 
 
76
 
 
32
22
 
 
1.6
 
 
33
19
 
 
0.7
 
 
32
16
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: BBC Weather[3]
Imperial conversion
JFMAMJJASOND
 
 
0
 
 
89
60
 
 
0
 
 
92
62
 
 
0
 
 
93
64
 
 
0
 
 
91
66
 
 
0.1
 
 
89
69
 
 
2.5
 
 
89
73
 
 
9.1
 
 
87
74
 
 
14
 
 
86
74
 
 
10
 
 
88
73
 
 
3
 
 
89
72
 
 
0.1
 
 
91
66
 
 
0
 
 
89
61
Average max. and min. temperatures in °F
Precipitation totals in inches
Monte Cristi, Dominican Republic
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
74
 
 
29
19
 
 
47
 
 
29
20
 
 
48
 
 
30
20
 
 
59
 
 
31
21
 
 
60
 
 
32
22
 
 
40
 
 
33
23
 
 
22
 
 
34
23
 
 
28
 
 
34
23
 
 
35
 
 
34
23
 
 
68
 
 
33
22
 
 
108
 
 
31
21
 
 
84
 
 
29
20
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: NOAA[4]
Imperial conversion
JFMAMJJASOND
 
 
2.9
 
 
84
67
 
 
1.9
 
 
85
67
 
 
1.9
 
 
86
68
 
 
2.3
 
 
87
70
 
 
2.4
 
 
89
72
 
 
1.6
 
 
92
73
 
 
0.8
 
 
92
74
 
 
1.1
 
 
93
74
 
 
1.4
 
 
93
73
 
 
2.7
 
 
91
72
 
 
4.3
 
 
87
70
 
 
3.3
 
 
85
68
Average max. and min. temperatures in °F
Precipitation totals in inches
Brasília, Brazil
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
241
 
 
27
17
 
 
215
 
 
27
17
 
 
189
 
 
27
18
 
 
124
 
 
27
17
 
 
39
 
 
26
15
 
 
8.8
 
 
25
13
 
 
12
 
 
25
13
 
 
13
 
 
27
15
 
 
52
 
 
28
16
 
 
172
 
 
28
17
 
 
238
 
 
27
18
 
 
249
 
 
26
18
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: World Weather Information Service [1]
Imperial conversion
JFMAMJJASOND
 
 
9.5
 
 
80
63
 
 
8.5
 
 
80
63
 
 
7.4
 
 
81
64
 
 
4.9
 
 
80
62
 
 
1.5
 
 
78
59
 
 
0.3
 
 
77
56
 
 
0.5
 
 
77
55
 
 
0.5
 
 
81
58
 
 
2
 
 
83
61
 
 
6.8
 
 
82
63
 
 
9.4
 
 
80
64
 
 
9.8
 
 
79
64
Average max. and min. temperatures in °F
Precipitation totals in inches
Darwin, Australia
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
466
 
 
32
25
 
 
373
 
 
32
25
 
 
335
 
 
32
25
 
 
108
 
 
33
24
 
 
25
 
 
32
23
 
 
2.3
 
 
31
20
 
 
1.2
 
 
31
20
 
 
5.8
 
 
32
20
 
 
18
 
 
33
23
 
 
65
 
 
34
25
 
 
137
 
 
34
26
 
 
276
 
 
33
26
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: Australian Bureau of Meteorology [2]
Imperial conversion
JFMAMJJASOND
 
 
18
 
 
89
77
 
 
15
 
 
89
77
 
 
13
 
 
90
76
 
 
4.2
 
 
91
76
 
 
1
 
 
90
73
 
 
0.1
 
 
87
68
 
 
0
 
 
87
67
 
 
0.2
 
 
89
69
 
 
0.7
 
 
91
74
 
 
2.6
 
 
92
77
 
 
5.4
 
 
92
78
 
 
11
 
 
91
78
Average max. and min. temperatures in °F
Precipitation totals in inches
Tegucigalpa, Honduras
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
5.3
 
 
26
14
 
 
4.7
 
 
27
15
 
 
9.9
 
 
30
16
 
 
43
 
 
30
17
 
 
144
 
 
30
18
 
 
159
 
 
29
18
 
 
82
 
 
28
18
 
 
89
 
 
29
18
 
 
177
 
 
29
18
 
 
109
 
 
27
18
 
 
40
 
 
26
16
 
 
9.9
 
 
25
15
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: WMO[5]
Imperial conversion
JFMAMJJASOND
 
 
0.2
 
 
78
58
 
 
0.2
 
 
81
58
 
 
0.4
 
 
85
60
 
 
1.7
 
 
86
63
 
 
5.6
 
 
86
65
 
 
6.2
 
 
83
65
 
 
3.2
 
 
82
64
 
 
3.5
 
 
83
64
 
 
7
 
 
83
64
 
 
4.3
 
 
81
64
 
 
1.6
 
 
79
61
 
 
0.4
 
 
78
59
Average max. and min. temperatures in °F
Precipitation totals in inches
Ho Chi Minh City, Vietnam
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
14
 
 
32
21
 
 
4.1
 
 
33
23
 
 
11
 
 
34
24
 
 
50
 
 
35
26
 
 
218
 
 
34
25
 
 
312
 
 
32
25
 
 
294
 
 
32
24
 
 
270
 
 
32
24
 
 
327
 
 
31
24
 
 
267
 
 
31
24
 
 
117
 
 
31
23
 
 
48
 
 
31
21
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: Vietnam Institute for Building Science and Technology [3]
Imperial conversion
JFMAMJJASOND
 
 
0.5
 
 
89
70
 
 
0.2
 
 
91
73
 
 
0.4
 
 
93
76
 
 
2
 
 
94
78
 
 
8.6
 
 
93
77
 
 
12
 
 
90
76
 
 
12
 
 
90
76
 
 
11
 
 
89
76
 
 
13
 
 
88
76
 
 
11
 
 
88
75
 
 
4.6
 
 
88
73
 
 
1.9
 
 
87
71
Average max. and min. temperatures in °F
Precipitation totals in inches
Bengaluru, India
Climate chart (explanation)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
1.6
 
 
28
16
 
 
7.1
 
 
31
18
 
 
15
 
 
33
20
 
 
62
 
 
34
22
 
 
129
 
 
33
22
 
 
110
 
 
30
21
 
 
116
 
 
28
20
 
 
163
 
 
28
20
 
 
208
 
 
29
20
 
 
186
 
 
29
20
 
 
65
 
 
27
18
 
 
15
 
 
27
16
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: India Meteorological Department [4]
Imperial conversion
JFMAMJJASOND
 
 
0.1
 
 
83
61
 
 
0.3
 
 
88
64
 
 
0.6
 
 
92
68
 
 
2.4
 
 
93
72
 
 
5.1
 
 
92
71
 
 
4.3
 
 
85
69
 
 
4.6
 
 
83
68
 
 
6.4
 
 
83
68
 
 
8.2
 
 
83
68
 
 
7.3
 
 
83
68
 
 
2.5
 
 
81
65
 
 
0.6
 
 
80
62
Average max. and min. temperatures in °F
Precipitation totals in inches

See also

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References

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  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. ^ Smart, Matthew P (2019). Thought, Action; Impact: Modes of Presentation to Enable an Immersive Reader-Response (Thesis). Queensland University of Technology. doi:10.5204/thesis.eprints.127474.
  3. ^ "World Weather Information Service — Banjul". Retrieved 3 March 2020.
  4. ^ "Station Name: MONTE CRISTI ... Country: DOMINICAN REPUBLIC". NOAA.
  5. ^ "Weather Information for Tegucigalpa, Country: HONDURAS". WMO.