Subtropics

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The subtropics and tropics
Areas of the world with subtropical climates

The subtropics are geographic and climate zones located roughly between the tropics at latitude 23.5° (the Tropic of Cancer and Tropic of Capricorn) and temperate zones (normally referring to latitudes 35–66.5°) north and south of the Equator.

Subtropical climates are often characterized by warm to hot summers and cool to mild winters with infrequent frost. Most subtropical climates fall into two basic types - humid subtropical, where rainfall is often concentrated in the warmest months (for example Brisbane or Jacksonville, Florida) and dry summer (or Mediterranean), where seasonal rainfall is concentrated in the cooler months (for example Naples, Italy or Los Angeles, California).

Subtropical climates can occur at high elevations within the tropics, such as in the southern end of the Mexican Plateau and in Vietnam and Taiwan. Six climate classifications use the term to help define the various temperature and precipitation regimes for the planet Earth.

A great portion of the world's deserts are located within the subtropics, due to the development of the subtropical ridge. Within savanna regimes in the subtropics, a wet season is seen annually during the summer, which is when most of the yearly rainfall falls. Within Mediterranean climate regimes, the wet season occurs during the winter. Areas bordering warm oceans are prone to locally heavy rainfall from tropical cyclones, which can contribute a significant percentage of the annual rainfall. Plants such as palms, citrus, mango, pistachio, lychee, and avocado are grown within the subtropics.

Definition

The tropics have been historically defined as lying between the Tropic of Cancer and Tropic of Capricorn, located at 23.45° north and south latitude respectively.[1] The poleward fringe of the subtropics is located at approximately 40° north and south latitude respectively.[2]

Temperatures

Tadrart Acacus desert, part of the Sahara, in western Libya.

Several methods have been used to define the subtropical climate. In the Trewartha climate classification, a subtropical region should have at least eight months with a mean temperature greater than 10 °C (50.0 °F) and at least one month with a mean temperature under 18 °C (64.4 °F).[3] German climatologists Carl Troll and Karlheinz Paffen defined Warm temperate zones as plain and hilly lands having an average temperature of the coldest month between 2 °C (35.6 °F) and 13 °C (55.4 °F) in the Northern Hemisphere and between 6 °C (42.8 °F) and 13 °C (55.4 °F) in the Southern Hemisphere, excluding oceanic and continental climates. According to the Troll-Paffen climate classification, there generally exists one large subtropical zone named the warm-temperate subtropical zone,[4] which is subdivided into seven smaller areas.[5]

According to the E. Neef climate classification, the subtropical zone is divided into two parts: Rainy winters of the west sides and Eastern subtropical climate.[6] According to the Wilhelm Lauer & Peter Frankenberg climate classification, the subtropical zone is divided into three parts: high-continental, continental, and maritime.[7] According to the Siegmund/Frankenberg climate classification, subtropical is one of six climate zones in the world.[8]

Rainfall

Hadley cells located on the Earth's atmospheric circulation.

Heating of the earth near the equator leads to large amounts of upward motion and convection along the monsoon trough or intertropical convergence zone. The upper-level divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft. As the air moves towards the mid-latitudes, it cools and sinks, which leads to subsidence near the 30th parallel of both hemispheres. This circulation is known as the Hadley cell and leads to the formation of the subtropical ridge.[9] Many of the world's deserts are caused by these climatological high-pressure areas,[10] located within the subtropics. This regime is known as an arid subtropical climate, which is generally located in areas adjacent to powerful cold ocean currents. Examples of this climate are the coastal areas of southern Africa (Namibia, South Africa), the south of the Canary Islands and the coasts of Peru and Chile.[11]

The humid or monsoon subtropical climate is often located on the western side of the subtropical high. Here, unstable tropical airmasses in summer bring convective overturning and frequent tropical downpours in the hot season. In the winter (dry season) the monsoon retreats, and the drier trade winds bring more stable airmass and often dry weather. Areas that have this type of subtropical climate include Australia, Southeast Asia, parts of South America, and the deep south of the United States.[12][13][14] Monsoon regions with a wet season include western Mexico.[15] the Desert Southwest of the United States,[16] Within the Mediterranean climate regime, the west coast of the United States and the Mediterranean coastline of Italy, Greece,[17] and Turkey experience a wet season in the winter months.[18] Similarly, the wet season in the Negev desert of Israel extends from October through May.[19] At the boundary between the Mediterranean and monsoon climates in North America lies the Sonoran desert, which receives the two rainy seasons associated with each climate regime.[20]

In areas bounded by warm ocean, tropical cyclones can contribute significantly to local rainfall within the subtropics.[21] Japan receives over half of its rainfall from typhoons.[22]

Flora

These climates do not routinely see hard frosts or snow, which allows plants such as palms and citrus to flourish.[23][24] As one moves toward the tropical side the slight winter cool season disappears, while at the poleward threshold of the subtropics the winters become cooler. Some crops which have been traditionally farmed in tropical climates, such as mango, litchi, and avocado, are cultivated in the subtropics. Pest control of the crops is less difficult than within the tropics, due to the cooler winters.[25]

Tree ferns (pteridophytes) are grown within subtropical areas, primarily within the subtropics and within topography within the tropics. Dracaena and yucca can grow within the subtropics. Trees within the Taxaceae family grow within subtropical climate regimes. Apple, pear pomegranate grows well [26]

Varieties

Humid variation

Wetland Park in Hong Kong.

The humid subtropical climate is a subtropical climate type characterized by hot, humid summers with frequent tropical downpours of short duration and warm, and frequently dry winters. In summer, the subtropical high pressure cells bring a sultry flow of tropical air with high dew points, and daily thundershowers are typical, though brief. Normally, rainfall is concentrated in the warmest months of the year. At times, the average annual precipitation may be more evenly distributed throughout the year, or a spring maximum is present. With decreasing latitude most humid subtropical climates have drier winters and wetter summers typically, such as the USA state of Florida and southeast Asia.

Humid subtropical climates lie on the lower east side of continents, roughly between latitudes 25° and 40° degrees away from the equator.[27]

Hong Kong
Climate chart (explanation)
J F M A M J J A S O N D
 
 
25
 
 
19
14
 
 
52
 
 
19
14
 
 
71
 
 
22
17
 
 
189
 
 
25
21
 
 
330
 
 
28
24
 
 
388
 
 
30
26
 
 
374
 
 
31
27
 
 
445
 
 
31
26
 
 
288
 
 
30
26
 
 
152
 
 
28
23
 
 
35
 
 
24
19
 
 
35
 
 
20
16
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: HKO
São Paulo
Climate chart (explanation)
J F M A M J J A S O N D
 
 
239
 
 
27
19
 
 
217
 
 
28
19
 
 
160
 
 
27
18
 
 
76
 
 
25
16
 
 
74
 
 
23
14
 
 
56
 
 
22
12
 
 
44
 
 
22
12
 
 
39
 
 
23
13
 
 
81
 
 
24
14
 
 
124
 
 
25
15
 
 
146
 
 
26
17
 
 
201
 
 
26
18
Average max. and min. temperatures in °C
Precipitation totals in mm
Tampa
Climate chart (explanation)
J F M A M J J A S O N D
 
 
2.4
 
 
71
49
 
 
2.4
 
 
74
52
 
 
3.8
 
 
78
56
 
 
2.6
 
 
83
60
 
 
3.5
 
 
88
66
 
 
7.6
 
 
91
72
 
 
7.3
 
 
92
74
 
 
7.1
 
 
92
74
 
 
6.1
 
 
90
73
 
 
3.3
 
 
85
66
 
 
2.2
 
 
78
59
 
 
2.6
 
 
73
52
Average max. and min. temperatures in °F
Precipitation totals in inches

Mediterranean climate

The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of coastal southwestern North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot dry summers and rainfall in winter,[28] in areas under the constant influence of the subtropical ridge. Inland from the immediate coastlines, mediterranean climates can take on extreme temperatures. This is seen in inland California as well as Andalusia in Spain. In Europe, the northernmost mediterranean climates are found along the French Riviera, located at 43° latitude. On the immediate Atlantic coastline, the mediterranean boundary goes between Porto and Vigo at around 41° latitude. Parts of southwestern Australia around Perth have a Mediterranean climate as does areas around coastal South Africa.

Los Angeles
Climate chart (explanation)
J F M A M J J A S O N D
 
 
79
 
 
20
9
 
 
97
 
 
20
10
 
 
62
 
 
21
11
 
 
23
 
 
23
12
 
 
6.6
 
 
24
14
 
 
2.3
 
 
26
16
 
 
0.3
 
 
28
18
 
 
1
 
 
29
18
 
 
6.1
 
 
28
17
 
 
17
 
 
26
15
 
 
26
 
 
23
11
 
 
59
 
 
20
9
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: [1]
Perth
Climate chart (explanation)
J F M A M J J A S O N D
 
 
9.5
 
 
31
18
 
 
13
 
 
31
18
 
 
19
 
 
30
16
 
 
44
 
 
26
14
 
 
118
 
 
22
11
 
 
177
 
 
19
9
 
 
170
 
 
18
8
 
 
134
 
 
19
8
 
 
81
 
 
20
10
 
 
52
 
 
23
11
 
 
22
 
 
26
14
 
 
13
 
 
29
16
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: BoM[29]
Cape Town
Climate chart (explanation)
J F M A M J J A S O N D
 
 
15
 
 
26
16
 
 
17
 
 
27
16
 
 
20
 
 
25
14
 
 
41
 
 
23
12
 
 
69
 
 
20
9
 
 
93
 
 
18
8
 
 
82
 
 
18
7
 
 
77
 
 
18
8
 
 
40
 
 
19
9
 
 
30
 
 
21
11
 
 
14
 
 
24
13
 
 
17
 
 
25
15
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: HKO

Semi-desert/desert climate

Mount Benacantil, Alicante, Spain.

Arid subtropical climates are characterized by an annual average temperature above 18 °C (64.4 °F), the absence of regular rainfall and high humidity. Mild climate variants are generally located in areas adjacent to powerful cold ocean currents. Examples of this climate, the coastal areas of southern Africa (Namibia, South Africa), south of the Canary Islands and the coasts of Peru and Chile. [11]

Alicante
Climate chart (explanation)
J F M A M J J A S O N D
 
 
22
 
 
17
6
 
 
26
 
 
18
7
 
 
26
 
 
19
8
 
 
30
 
 
21
10
 
 
33
 
 
24
13
 
 
17
 
 
27
17
 
 
6
 
 
30
20
 
 
8
 
 
30
20
 
 
47
 
 
28
18
 
 
52
 
 
24
14
 
 
42
 
 
21
10
 
 
26
 
 
18
7
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: AEdM
Cairo
Climate chart (explanation)
J F M A M J J A S O N D
 
 
5
 
 
19
9
 
 
3.8
 
 
20
10
 
 
3.8
 
 
24
12
 
 
1.1
 
 
28
15
 
 
0.5
 
 
32
18
 
 
0.1
 
 
34
20
 
 
0
 
 
35
22
 
 
0
 
 
34
22
 
 
0
 
 
33
21
 
 
0.7
 
 
29
17
 
 
3.8
 
 
25
14
 
 
5.9
 
 
20
10
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: WMO
Lima
Climate chart (explanation)
J F M A M J J A S O N D
 
 
0.9
 
 
26
19
 
 
0.3
 
 
27
19
 
 
4.9
 
 
26
19
 
 
0
 
 
24
18
 
 
0.1
 
 
22
16
 
 
0.3
 
 
20
15
 
 
0.3
 
 
19
15
 
 
0.3
 
 
18
15
 
 
5.4
 
 
19
15
 
 
0.2
 
 
20
15
 
 
0
 
 
22
16
 
 
0.3
 
 
24
18
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: WMO

See also

References

  1. ^ I. G. Sitnikov. "1". Principal Weather Systems in Subtropical and Tropical Zones (PDF). 1. Encyclopedia of Life Support Systems. 
  2. ^ Glossary of Meteorology (2012-04-25). "Subtropics". American Meteorological Society. Retrieved 2013-03-24. 
  3. ^ Belda et al. Climate classification revisited: from Köppen to Trewartha. In: Climate Research Vol. 59: 1-13, 2014.
  4. ^ Climatic map by Istituto Geografico De Agostini, according to Troll-Paffen climate classification Archived 2012-10-04 at the Wayback Machine.
  5. ^ Die Klimaklassifikation nach Troll / Paffen – klimadiagramme.de
  6. ^ Die Klimaklassifikation nach E. Neef – klimadiagramme.de
  7. ^ Wilhelm Lauer & Peter Frankenberg climate classification
  8. ^ Die Klimatypen der Erde – Pädagogische Hochschule in Heidelberg
  9. ^ Dr. Owen E. Thompson (1996). Hadley Circulation Cell. Archived 2009-03-05 at the Wayback Machine. Channel Video Productions. Retrieved on 2007-02-11.
  10. ^ ThinkQuest team 26634 (1999). The Formation of Deserts. Archived 2012-10-17 at the Wayback Machine. Oracle ThinkQuest Education Foundation. Retrieved on 2009-02-16.
  11. ^ a b http://www.britannica.com/EBchecked/topic/606540/tropical-and-subtropical-desert-climate
  12. ^ Susan Woodward (2005-02-02). "Tropical Savannas". Radford University. Archived from the original on 2008-02-25. Retrieved 2008-03-16. 
  13. ^ Randy Lascody (2008). The Florida Rain Machine. National Weather Service. Retrieved on 2009-02-06.
  14. ^ John J. Stransky (1960-01-01). "Site Treatments Have Little Effect During Wet Season in Texas". Tree Planters' Notes. 10 (2). 
  15. ^ Remote Sensing for Migratory Creatures (2002). Phenology and Creature Migration: Dry season and wet season in West Mexico. Arizona Remote Sensing Center. Retrieved on 2009-02-06.
  16. ^ J. Horel (2006). Normal Monthly Precipitation, Inches. Archived 2006-11-13 at the Wayback Machine. University of Utah. Retrieved on 2008-03-19.
  17. ^ Greek Embassy London (2008). Welcome to Greece. Government of Greece. Retrieved on 2009-02-06.
  18. ^ D. Bozkurt, O.L. Sen and M. Karaca (2008). Wet season evaluation of RegCM3 performance for Eastern Mediterranean. EGU General Assembly. Retrieved on 2009-02-06.
  19. ^ Ron Kahana; Baruch Ziv; Yehouda Enzel & Uri Dayan (2002). "Synoptic Climatology of Major Floods in the Negev Desert, Israel" (PDF). International Journal of Climatology. 22 (7): 869. Bibcode:2002IJCli..22..867K. doi:10.1002/joc.766. 
  20. ^ Michael J. Plagens (2009). What and Where is the Sonoran Desert? Arizonensis. Retrieved on 2009-02-07.
  21. ^ Geoffrey John Cary; David B. Lindenmayer; Stephen Dovers (2003). Australia Burning: Fire Ecology, Policy and Management Issues. Csiro Publishing. p. 33. ISBN 9780643069268. Retrieved 2013-03-24. 
  22. ^ Whipple, Addison (1982). Storm. Alexandria, VA: Time Life Books. p. 54. ISBN 0-8094-4312-0. 
  23. ^ Walter Tennyson Swingle (1904). The Date Palm and its Utilization in the Southwestern States. United States Government Printing Office. p. 11. Retrieved 2013-03-24. 
  24. ^ Wilson Popenoe (1920). Manual of Tropical and Subtropical Fruits: Excluding the Banana, Coconut, Pineapple, Citrus Fruits, Olive, and Fig. The Macmillan Company. p. 7. Retrieved 2013-03-24. 
  25. ^ Galán Saúco, V. Robinson, J. C., Tomer, E., Daniells, J. (2010). "S18.001: Current Situation and Challenges of Cultivating Banana and other Tropical Fruits in the Subtropics" (PDF). 28th International Horticultural Congress. Retrieved 2013-03-24. 
  26. ^ R. K. Kholi; D. R. Batish & H. B. SIngh. "Forests and Forest Plants Volume II – Important Tree Species" (PDF). Encyclopedia of Life Support Systems. Retrieved 2013-04-09. 
  27. ^ Michael Ritter (2008-12-24). "Humid Subtropical Climate". University of Wisconsin–Stevens Point. Archived from the original on 2008-10-14. Retrieved 2008-03-16. 
  28. ^ Michael Ritter (2008-12-24). "Mediterranean or Dry Summer Subtropical Climate". University of Wisconsin–Stevens Point. Archived from the original on 2009-08-05. Retrieved 2009-07-17. 
  29. ^ "Perth Monthly climate statistics". Australia Bureau of Meteorology. Retrieved 2010-08-02. 
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