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Arid Climates and Continental Margins: A Comprehensive Overview

November 29, 2023 712 0

Arid Climates and Continental Margins

Dry climates, categorized under Group B in the Köppen climate classification, encompass regions characterized by minimal precipitation. Spanning latitudes between 15° and 60° N and S of the equator, these climates manifest diverse patterns influenced by subtropical highs, continental margins, and geographic features. This article delves into the intricacies of dry climates, exploring their classifications, characteristics, and subdivisions, shedding light on the nuanced climatic phenomena shaping these arid landscapes.

Dry Climates: Exploring Arid Regions and Continental Margins Worldwide

Dry climates, as classified in the Köppen system, are characterized by low levels of precipitation and are typically found between 15° to 60° N and S of the equator. These climates are associated with specific geographical and meteorological conditions:

  • Subtropical Highs: In the low latitudes, between 15° and 30°, dry climates occur in the areas influenced by subtropical high-pressure systems
    • These areas experience sinking air, which inhibits cloud formation and rainfall. 
    • This is a common feature in subtropical desert regions.
  • Western Continental Margins: Dry climates extend more equatorwards on the western margins of continents. 
    • Coastal regions, such as the west coast of South America, are often affected, resulting in arid conditions.
  • Middle Latitudes: In middle latitudes, dry climates occur between 35° to 60° N and S. 
    • They are typically found in the interior of continents, where moist maritime winds do not reach. 
    • Additionally, some dry climates are located in areas surrounded by mountain ranges that block the passage of humid air.

Arid Climates: Köppen’s Dry Climate Types and Subdivisions

  • Steppe or Semi-Arid Climate (BS): This classification (BS) includes regions with low rainfall but still more moisture than true deserts along continental margins.
    • These areas may support grasslands and sparse vegetation.
  • Desert Climate (BW): The designation BW is given to true desert climates with extremely low precipitation levels and arid conditions along continental margins.
    • These regions often have little to no vegetation.
    • Both steppe and desert climates are further subdivided based on their specific geographical locations and characteristics. For example:
  • Subtropical Steppe (BSh) and Subtropical Desert (BWh): Found at latitudes between 15° to 35° along continental margins experience arid to semi-arid conditions, often associated with subtropical high-pressure systems.
  • Mid-Latitude Steppe (BSk) and Mid-Latitude Desert (BWk): Located at latitudes between 35° to 60° along continental margins are characterized by low precipitation levels and arid climates, with variations depending on specific geographic features.

Climate

Feature

Subtropical Steppe Climates

(BSh)

  • Subtropical steppe (BSh) and subtropical desert (BWh) have common precipitation and temperature characteristics.
  • This region is located in between humid and dry climates.
  • The subtropical steppe receives more rainfall than the desert, adequate enough for the growth of sparse grasslands.
  • The rainfall is highly variable.
Subtropical Desert Climates

(BWh)

  • Rain occurs in short intense thunder-showers in deserts and is ineffective in building soil moisture.
  • Fog is common in coastal deserts bordering cold currents.
  • Maximum temperature in the summer is very high.
  • The rainfall in this type of climate is highly variable.
  • The annual and diurnal ranges of temperature are also high.

Table : Types of Dry Climate

Warm Temperate Zones: Exploring Continental Edges and Seasons

  • These climates extend from 30° to 50° of latitude mainly on the eastern and western margins of continents, influenced by continental margins.
  • They have warm summers with mild winters.
  • They are grouped into four types:
    • Cwa – Humid subtropical, i.e. dry in winter and hot in summer;
    • Cs – Mediterranean;
    • Cfa – Humid subtropical, i.e. no dry season and mild winter;
    • Cfb – Marine west coast climate.

Climate

Feature

Humid Subtropical Climate

(Cwa)

  • Mainly occurs poleward of Tropic of Cancer and Tropic of Capricorn.
  • It is found mainly in North Indian plains and South China interior plains.
  • The climate is similar to Aw climate except that the temperature in winter is warm.
Mediterranean Climate (Cs)
  • Occurs around the Mediterranean sea, along the west coast of continents in subtropical latitudes between 30° to 40°, covering regions of Central California, Central Chile, along the coast in south eastern and south western Australia, influenced by continental margins.
  • These areas come under the influence of subtropical high in summer and westerly wind in winter.
  • The climate is characterized by hot, dry summers and mild, rainy winters.
  • Monthly average temperature in summer is around 25° C and in winter below 10°C.
  • The annual precipitation ranges between 35 – 90 cm.
Humid Subtropical Climate

(Cfa)

  • Mainly lies on the eastern parts of the continent in subtropical latitudes, covering eastern United States of America, southern and eastern China, southern Japan, northeastern Argentina, coastal south Africa and eastern coast of Australia.
  • Here, air masses are generally unstable and cause rainfall throughout the year.
  • The annual averages of precipitation vary from 75-150 cm.
  • Thunderstorms in summer and frontal precipitation in winter are common.
  • Mean monthly temperature in summer is around 27°C, and in winter it varies from 5°-12° C.
  • The daily range of temperature is small.
Marine West Coast Climate

(Cfb)

  • Marine west coast climate is located poleward from the Mediterranean climate on the west coast of the continents.
  • The main areas where this climate is found are Northwestern Europe, west coast of North America, north of California, southern Chile, southeastern Australia and New Zealand.
  • Due to marine influence, the temperature is moderate and in winter, it is warmer than usual.
  • The mean temperature in summer months is between 15°to 20°C and in winter 4°to 10°C.
  • The annual and daily ranges of temperature are small.
  • Precipitation occurs throughout the year. Precipitation varies greatly from 50-250cm.

Table: Subdivision Warm Temperate (Mid-Latitude) Climates

Cold Snow Forests: Exploring Northern Hemisphere’s Winter Climates

  • Cold snow forest climates occur in the large continental area in the northern hemisphere between 40°-70° north latitudes in Europe, Asia and North America, influenced by continental margins.
  • Cold snow forest climates are divided into two types:
    • Df – cold climate with humid winter;
    • Dw – cold climate with dry winter.

Climate

Feature

Cold Climate with Humid Winters

(Df)

  • Cold climate with humid winter occurs poleward of marine west coast climate and mid latitude steppe.
  • The winters are cold and snowy.
  • The frost free season is very short. 
  • The annual ranges of temperature are large.
  • The weather changes are abrupt and short.
  • Poleward, the winters are more severe.
Cold Climate with Dry Winters

(Dw)

  • Cold climates with dry winters occur mainly over Northeastern Asia.
  • The development of winter anticyclone and its weakening in summer sets in monsoon like reversal of wind in this region.
  • Poleward, summer temperatures are lower and winter temperatures are extremely low with many locations experiencing below freezing point temperatures for up to seven months in a year.
  • Precipitation occurs in summer. The annual precipitation is low from 12-15 cm.

Table : Subdivision of Cold Snow Forest Climates

Polar Frontiers: Exploring Tundra and Ice Cap Climates

  • Polar climates exist poleward beyond 70° Latitude.
  • This type of climate is further subdivided in two types:
    • ET – Tundra Climate;
    • EF – Ice Cap Climate

Climate

Feature

Tundra Climate

(ET)

  • The Tundra climate (ET) is so called after the types of vegetation, like low growing mosses, lichens and flowering plants.
  • This is the region of permafrost where the subsoil is permanently frozen.
  • The short growing season and water logging support only low growing plants. During summer, the tundra regions have a very long duration of daylight.
Ice Cap Climate

(EF)

  • The Ice Cap climate (EF) is found in Greenland and Antarctica.
  • The temperature is below the freezing point in summer.
  • This area receives very little precipitation.
  • The snow and ice get accumulated and the mounting pressure causes the deformation of the ice sheets and they break. They move as icebergs that float in the Arctic and Antarctic waters.
  • Antarctica, which is at 79° S, portrays an Ice Cap type of climate.

Table: Subdivision of Polar Climates

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 Final Result – CIVIL SERVICES EXAMINATION, 2023.   Udaan-Prelims Wallah ( Static ) booklets 2024 released both in english and hindi : Download from Here!     Download UPSC Mains 2023 Question Papers PDF  Free Initiative links -1) Download Prahaar 3.0 for Mains Current Affairs PDF both in English and Hindi 2) Daily Main Answer Writing  , 3) Daily Current Affairs , Editorial Analysis and quiz ,  4) PDF Downloads  UPSC Prelims 2023 Trend Analysis cut-off and answer key

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UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
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Quick Revise Now !
UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
Integration of PYQ within the booklet
Designed as per recent trends of Prelims questions
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