Semi-arid climate

A semi-arid climate, semi-desert climate, or steppe climate is a

.

Defining attributes of semi-arid climates

A more precise definition is given by the

as they usually cannot support forests.

To determine if a location has a semi-arid climate, the precipitation threshold must first be determined. The method used to find the precipitation threshold (in millimeters):

• multiply by 20 the average annual temperature in degrees Celsius and then
  • add 280 if at least 70% of the total precipitation falls in the summer half of the year (April–September in the northern hemisphere, October–March in the southern hemisphere)
  • add 140 if 30–70% of the total precipitation falls in the summer half of the year
  • add nothing if less than 30% of the total precipitation falls in the summer half of the year

If the area's annual precipitation in millimeters is less than the threshold but more than half or 50% the threshold, it is classified as a BS (steppe or semi-arid climate).^[1]

Furthermore, to delineate hot semi-arid climates from cold semi-arid climates, a mean annual temperature of 18 °C (64.4 °F) is used as an isotherm. A location with a BS-type climate is classified as hot semi-arid (BSh) if its mean temperature is above this isotherm, and cold semi-arid (BSk) if not.

Hot semi-arid climates

Hot semi-arid climates (type "BSh") tend to be located in the 20s and 30s latitudes of the

climates. These climates tend to have hot, or sometimes extremely hot, summers and warm to cool winters, with some to minimal precipitation. Hot semi-arid climates are most commonly found around the fringes of subtropical deserts.

Hot semi-arid climates are most commonly found in Africa, Australia, and South Asia. In Australia, a large portion of the Outback surrounding the central desert regions lies within the hot semi-arid climate region.^{[2][clarification needed]} In South Asia, both India and parts of Pakistan experience the seasonal effects of monsoons and feature short but well-defined wet seasons, but are not sufficiently wet overall to qualify as either a tropical savanna or a humid subtropical climate.

Hot semi-arid climates can be also found in parts of North America, such as most of northern Mexico, the ABC Islands, the rain shadows of Hispaniola's mountain ranges in the Dominican Republic and Haiti, parts of the Southwestern United States, and sections of South America such as the sertão, the Gran Chaco, and the poleward side of the arid deserts, where they typically feature a Mediterranean precipitation pattern, with generally rainless summers and wetter winters. They are also found in few areas of Europe surrounding the Mediterranean Basin. In Europe, BSh climates are primarily found in southeastern Spain,^[3][4] various parts of south Greece,^{[5] [6]} and marginal areas of Portugal and Cyprus.

Cold semi-arid climates

Cold semi-arid climates (type "BSk") tend to be located in elevated portions of

during the winter, though snowfall is much lower than at locations at similar latitudes with more humid climates.

Areas featuring cold semi-arid climates tend to have higher elevations than areas with hot semi-arid climates, and tend to feature major temperature swings between day and night, sometimes by as much as 20 °C (36 °F) or more. These large

, with dry summers, relatively wet winters, and even wetter springs and autumns.

Cold semi-arid climates are most commonly found in East Asia, the Middle East, including other parts of Asia, and Western North America. However, they can also be found in Northern Africa, South Africa, Europe (Central parts of Spain, Crimea, Greece, and North Macedonia), sections of South America and sections of interior southern Australia (e.g. Kalgoorlie and Mildura) and southern New Zealand (Alexandra).

Charts of selected cities

Patos, Paraíba, Brazil
Climate chart (explanation)
J F M A M J J A S O N D     66     32 22     139     32 22     213     31 22     177     30 22     55     29 21     28     27 21     12     27 20     3     28 20     1     30 20     4     31 21     8     32 21     22     32 21 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: [7]
Imperial conversion J F M A M J J A S O N D     2.6     90 71     5.5     89 71     8.4     88 71     7     86 71     2.2     84 71     1.1     81 69     0.5     81 67     0.1     82 67     0     85 69     0.2     88 69     0.3     89 70     0.9     90 71 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Kalgoorlie, Australia
Climate chart (explanation)
J F M A M J J A S O N D     27     34 18     32     32 18     25     30 16     20     25 13     25     21 9     27     18 6     24     17 5     21     19 6     14     22 8     16     26 11     19     29 14     16     32 17 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: [8]
Imperial conversion J F M A M J J A S O N D     1.1     92 65     1.3     90 64     1     85 61     0.8     78 55     1     69 48     1.1     64 43     1     62 41     0.8     66 42     0.5     72 47     0.6     79 52     0.7     84 58     0.6     90 62 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Jaipur (Sanganer), India
Climate chart (explanation)
J F M A M J J A S O N D     8     19 4     12     22 7     6     29 12     4     34 17     16     38 21     66     38 23     216     31 22     231     29 20     80     30 19     23     30 15     3     25 9     3     20 5 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: India Weather On Web
Imperial conversion J F M A M J J A S O N D     0.3     66 39     0.5     72 45     0.2     84 54     0.2     93 63     0.6     100 70     2.6     100 73     8.5     88 72     9.1     84 68     3.1     86 66     0.9     86 59     0.1     77 48     0.1     68 41 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Niamey, Niger
Climate chart (explanation)
J F M A M J J A S O N D     0     33 16     0     36 19     3.9     39 23     5.7     41 27     35     40 28     69     37 26     154     34 24     171     33 23     92     34 24     9.7     38 24     0.7     36 20     0     33 17 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: Deutscher Wetterdienst[9]
Imperial conversion J F M A M J J A S O N D     0     91 61     0     96 66     0.2     102 73     0.2     106 80     1.4     104 82     2.7     99 78     6.1     93 75     6.7     91 74     3.6     94 74     0.4     100 76     0     97 67     0     92 62 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Murcia, Spain
Climate chart (explanation)
J F M A M J J A S O N D     25     17 5     28     18 6     30     21 8     27     23 10     32     27 13     20     31 17     5     34 20     10     34 21     27     30 18     44     26 14     32     20 9     21     17 6 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: Agencia Estatal de Meteorología[10]
Imperial conversion J F M A M J J A S O N D     1     62 40     1.1     65 43     1.2     70 46     1.1     74 49     1.3     80 56     0.8     88 63     0.2     93 69     0.4     94 70     1.1     87 64     1.7     78 57     1.3     69 48     0.8     63 42 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

Reno, Nevada, United States
Climate chart (explanation)
J F M A M J J A S O N D     26     8 −4     26     11 −2     19     14 1     12     18 3     12     23 8     13     29 11     4.6     33 14     5.8     33 13     8.9     28 9     13     21 4     21     13 −1     26     8 −4 █ Average max. and min. temperatures in °C █ Precipitation totals in mm Source: NOAA[11]
Imperial conversion J F M A M J J A S O N D     1     46 25     1     51 29     0.8     58 33     0.5     64 38     0.5     74 46     0.5     83 52     0.2     92 58     0.2     91 56     0.4     82 49     0.5     69 39     0.8     55 31     1     46 25 █ Average max. and min. temperatures in °F █ Precipitation totals in inches

See also

• Continental climate
• Dry climate
• Desert climate
• Dust Bowl (an era of devastating dust storms, mostly in the 1930s, in semi-arid areas on the Great Plains of the United States and Prairies of Canada)
• Goyder's Line (a boundary marking the limit of semi-arid climates in the Australian state of South Australia)
• Köppen climate classification
• Palliser's Triangle (semi-arid area of Canada)
• Ustic (Soil Moisture Regime)
• Wave height

References

External links

Wikimedia Commons has media related to Semi-arid climate.