Climate of Rajasthan : Introduction, Factors, Classification, Season Classification

Introduction

  • The belt of maximum rainfall in the world is called the Equator.
  • The monsoon (arrival) in India is called the ‘South-West Monsoon’.
  • The monsoon returning to India is called the ‘North-East Monsoon’.
  • Climate : The ‘long term phenomena’ of the atmosphere around the earth are called ‘climate’.
  • Climate is determined on the basis of the average seasonal conditions of 30 years.
  • Weather : The ‘short term phenomena’ of the atmosphere around the earth are called ‘weather’.
  • According to the temperature, the climate of Rajasthan is ‘Subtropical and arid type climate’.

Factors that Affect Climate

  1. Latitudinal position and expansion :-
    • The climate of Rajasthan is more influenced by low latitude (equator).
    • Low latitude : 0° latitude (equator)
    • High latitude : 90° latitude
  2. Distance from the sea :-
    • There is more humidity near the sea. And as the distance increases the humidity starts decreasing.
    • Humid conditions are less found in Rajasthan, because Rajasthan is located at a greater distance from the sea.
  3. Height Above Sea Level or Relief Feature :
    • Temperature decreases as height from sea level increases and temperature increases as height decreases.
    • Low relief conditions are more found in Rajasthan, hence the temperature is found to be high in Rajasthan.
    • Generally low temperature conditions are found in Southern Aravalli (Rajsamand, Udaipur, Sirohi) in Rajasthan, because Southern Aravalli is at a higher height from sea level.
  4. Location or Direction of Mountains :-
    • Mountains affect temperature and rainfall.
  5. Direction of Monsoon Winds :-
    • The direction of monsoon is from water to land in summer and from land to water in winter.
    • Generally in summer when monsoon winds blow from water part (ocean) towards land part (continent), then there is more humidity in monsoon winds.
    • Generally in winter when monsoon winds blow from land part (continent) towards water part (ocean), then there is less humidity in monsoon winds.
  6. Upper atmospheric wind circulation or jet stream :-
    • Note : Jet stream was discovered by C.R. Rossby in 1947.
  7. Ocean Currents :-
    • Due to cold oceanic currents, there is less rainfall.
    • Due to warm oceanic currents, there is more rainfall.

Note : The factor that most influences the climate is temperature.

Classification of Climate of Rajasthan

  • The climate of Rajasthan has been classified in two ways. Like-
    • (A) General Classification of Climate of Rajasthan
    • (B) Individual Classification of Climate of Rajasthan

(A) General Classification of Climate of Rajasthan :-

  • According to the general climate classification, the climate of Rajasthan is divided into 5 parts on the basis of temperature and rainfall. Like-

General Classification of Climate of Rajasthan

S. No.Type of ClimateRainfallPhysical Region
1Arid Zone Climate0 – 20 cmDesert
2Semi-Arid Climate20 – 40 cmDesert
3Sub Humid Climate40 – 60 cmAravalli
4Humid Climate60 – 80 cmEastern Plains
5Very Humid Climate80 – 120 cmHadoti

(B) Individual Classification of Climate of Rajasthan :-

  1. Koppen’s Climate Classification
  2. Trewartha’s Climate Classification
  3. Thornthwaite’s Climate Classification

1. Koppen’s Climate Classification :-

  • Dr. Vladimir Koppen has classified climate on the basis of vegetation, rainfall and temperature.
  • Koppen’s Climate Classification :-
    1. A : Tropical
    2. B (Rainfall) : BW– Dry Desert (W- Whole)
    3. B (Rainfall) : BS– Semi-Arid (S- Steppe)
    4. C : Sub Tropical
    5. D : Snow Type
    6. E : Polar Type
  • In his climate classification, D and E types of climate are not found in Rajasthan.
  • He has divided the climate of Rajasthan into 4 parts. Like-

Classification of Climate of Rajasthan According to Koppen

S. No.Climate RegionLocatedClimateVegetationExtensionFeatures
1AwIn the southern part of Rajasthan
(To the east of Aravalli)		Tropical-Humid TypeSavana TypeVagad : Banswara, Dungarpur, Pratapgarh
Hadoti : Southern Kota, Baran, Jhalawar, Partial Chittorgarh		Vegetation density is high in this region.
2BWhwTo the west of AravalliArid Hot Desert TypeXerophyteBikaner, Churu, Sri Ganganagar, Hanumangarh, JaisalmerIn this region, vegetation density is found to be less or sparse vegetation is found because rainfall is less in this region.
3BShwTo the west of AravalliSemi-Arid or Steppe TypeSteppe/Small Grass TypeLuni Basin : Pali, Jodhpur, Barmer, Jalore
Nagaur
Shekhawati : Sikar, Jhunjhunu, partly Churu		Livestock is found in abundance in this region.
According to Koppen, this region is the largest climatic region in Rajasthan.
4CwgTo the east of AravalliSub Tropical Sub Humid TypeDry-Deciduous TypeAlwar, Bharatpur, Deeg, Karauli, Dholpur, Ajmer, Kekri, Bhilwara, Shahpura, Bundi, Chittorgarh, Dausa, Rajsamand, Sirohi, Gangapur City, Sawai Madhopur, Tonk, Udaipur, Jaipur City, Jaipur RuralAgricultural productivity is high in this region, because this region is the most fertile climatic region or physical region.
Here : A- Tropical, BW- Arid Desert, BS- Semi Arid/Steppe, C- Sub Tropical, h- Average Temperature 18℃ and More Than, w- Winter Dry, g- Gangetic Plain Type Climate

2. Trewartha’s Climate Classification :-

  • He has divided the climate of Rajasthan into 4 parts, the main basis of which is rainfall. Like-

Classification of Climate of Rajasthan According to Trewartha

S. No.Climate RegionRainfallAverage Rainfall
1Aw80 – 120 cm100 cm
2BWh0 – 20 cm10 cm
3BSh20 – 40 cm30 cm
4Caw60 – 80 cm70 cm
Here : A- Tropical, BW- Arid Desert, BS- Semi Arid/Steppe, C- Sub Tropical, h- Average Temperature 18℃ and More Than, w- Winter Dry, a- Hot Summer Season

3. Thornthwaite’s Climate Classification :-

  • Thornthwaite has classified the climate on the basis of temperature, evaporation and rainfall.
  • Climate Classification of Thornthwaite Based on Rainfall :-
    1. A : Very Humid
    2. B : Humid
    3. C : Sub Humid
    4. D : Semi-Arid
    5. E : Arid
  • According to Thornthwaite, type A and B climate is not found in Rajasthan.
  • On the basis of temperature, evaporation and rainfall, he has divided the climate of Rajasthan into 4 parts. For example-

Classification of Climate of Rajasthan According to Thornthwait

S. No.Climate RegionClimateExtensionFeatures
1CA’wSub-Humid TypeHadoti : Southern Kota, Baran, Jhalawar, Partial Chittorgarh
Vagad : Dungarpur, Banswara, Pratapgarh
2DA’wSemi-Arid TypeAlwar, Bharatpur, Karauli, Dholpur, Ajmer, Bhilwara, Bundi, Chittorgarh, Dausa, Rajsamand, Sirohi, Sawai Madhopur, Tonk, Udaipur, Jaipur, Sikar, Jhunjhunu, Nagaur, Pali, Jalore, partly Jodhpur.According to Thornthwait, this is the largest climatic region in Rajasthan.
3DB’wArid & Semi-Arid TypeBikaner, Churu, Sri Ganganagar, Hanumangarh
4EA’dArid Desert TypeJaisalmer, Barmer, Western Jodhpur
Here : A’- Mega Thermal, B’- Meso Thermal, C- Sub Humid, D- Semi-Arid, E- Arid, w- Winter Dry, d- All Season Dry or Scarcity of Rainfall in All Season

Season Classification of Climate of Rajasthan

  • According to the climate, the seasons in Rajasthan are divided into 4 parts. For example-
    1. Summer Season (March – June)
    2. Rain Season (June – September)
    3. Autumn Season (October – November)
    4. Winter Season (December – February)

1. Summer Season :-

  • Time : from March to June
  • Average Temperature : 30℃ to 40℃
  • In summer, in Rajasthan-
    • The hottest district is Churu.
    • The hottest place is Phalodi (Phalodi).
    • The hottest month is June.
    • The coldest district is Sirohi.
    • The coldest place is Mount Abu (Sirohi).
  • The reason for Sirohi district being the coldest is the high elevation. That is, the temperature decreases as the altitude increases.
  • Range of Temperature :-
    • The difference between the maximum and minimum temperature in a given time is called range of temperature.
    • In Rajasthan-
      • The highest daily range of temperature is in Jaisalmer district
      • The highest annual range of temperature is in Churu district.
  • Phenomena :-
    1. Loo :-
      • Definition : Hot and dry winds blowing during summer are called Loo.
      • Cause : Advection/horizontal flow of winds or air
      • Affected area : North-Western Rajasthan (mostly Barmer)
      • Characteristic : Loo is a phenomenon of summer season, which increases the temperature.
    2. Dust Storm :-
      • Definition : Dusty and humid winds blowing during summer season are called Dust Storms.
      • Cause : Convection/vertical flow of winds or air
      • Affected area : Northern Rajasthan (mostly Sri Ganganagar : about 27 days)
      • Characteristic : Dust storm is a phenomenon of summer season, which reduces the temperature.
      • Direction : The direction of dust storms in Rajasthan is from west to east.
    3. Dust Cyclone :-
      • Definition : Dusty and cyclonic winds in summer are called Dust Cyclone (Bhabhulya).
      • Reason : Low air pressure in the center of a particular place and high air pressure in the circumference (air pressure is low in the center due to high temperature and high in the circumference due to low temperature.)
      • Affected area : North-Western Rajasthan (mostly Bikaner)

2. Rain Season :-

  • Time : from June to September
  • Phenomena :-
    1. Monsoon

Monsoon :-

  • Basic Word : The basic word of the word monsoon is ‘Mausim’, which is an Arabic word.
  • Father : Al-Masudi is considered to be the father of the word monsoon.
  • Meaning of monsoon : The change in season or the winds blowing from water to land are called monsoon winds.
  • Name of monsoon : The name of monsoon in India is South-West Monsoon, which comes from the Indian Ocean.

Date of Monsoon :-

  • Arrival Date of Monsoon :-
    • The first arrival of monsoon in India is on 22nd May. (Andaman and Nicobar)
    • The arrival of monsoon on the mainland of India is on 1st June. (Kerala/Malabar)
    • The arrival of monsoon in Rajasthan is on 25th June. (Banswara and Dungarpur)
  • Departure Date of Monsoon :-
    • The withdrawal of monsoon from entire India begins on 16th September.
    • The withdrawal of monsoon from entire India occurs on 31st October.
    • The withdrawal of monsoon from North India occurs on 1st October.
    • The withdrawal of monsoon from Rajasthan begins on 16th September.
    • The withdrawal of monsoon from Rajasthan occurs on 30th September.

Nature of Monsoon :-

  • In Rajasthan, monsoon arrives late and returns before time.

Branches of Monsoon :-

  1. Arabian Sea Branch : It is divided into three branches. Like-
    1. Western Ghats Branch
    2. Chhota Nagpur Branch
    3. Himachal Branch :-
      • The monsoon of this branch arrives in Rajasthan.
      • This is the branch of monsoon which brings monsoon first in Rajasthan, but this branch does not bring much rainfall in Rajasthan, because Aravalli is parallel to it.
      • This branch is the main source of rain (humidity) in Rajasthan.
  2. Bay of Bengal Branch :- It is divided into two branches. Like-
    1. Eastern Himalayan Branch
    2. Shivalik Branch :-
      • The monsoon of this branch comes to Rajasthan.
      • This branch contributes to more rainfall in Rajasthan.

Purwai/ Easterlies : The eastern monsoon winds coming from the Bay of Bengal to Rajasthan are called easterlies. Due to which there is more rainfall in the east of Aravalli in Rajasthan.

Effect of Monsoon :-

  • Effect of Monsoon in Rajasthan :-
  • In Rajasthan-
    • The average annual rainfall is 57.5 cm (575 mm).
    • The districts with the highest rainfall are Jhalawar, Banswara (currently receiving more rainfall). Where the average rainfall is 100 cm.
    • The place with the highest rainfall is Mount Abu (Sirohi). Where the average rainfall is 150 cm.
    • The only place with 150 cm or more rainfall is Mount Abu (Sirohi).
    • The districts with the lowest rainfall are Jaisalmer, Bikaner. Where the average rainfall is 10 cm.
    • The place with the lowest rainfall is Sam (Jaisalmer). Where the average rainfall is 0 cm (less than 1 cm).
  • Effect of Monsoon in Rajasthan According to Directions :-
  • In Rajasthan-
    • The direction of monsoon is South-West.
    • The direction of progress of monsoon is North-East.
    • The direction of increasing amount of monsoon (rainfall) is from North-West to South-East.
    • The direction of decreasing amount of monsoon (rainfall) is from South-East to North-West.
  • In Rajasthan-
    • The region with maximum rainfall is South Rajasthan.
    • The region with minimum rainfall is West Rajasthan.
    • The amount of rainfall increases when we move from North to South.
    • The amount of rainfall decreases when we move from South to North.
    • The amount of rainfall decreases when we move from East to West.
    • The amount of rainfall increases when we move from West to East.

Events During Monsoon :-

  1. Monsoon Bursting :-
    • Definition : The heavy rainfall at the beginning of the monsoon is called monsoon bursting.
    • Time : July/ August
  2. Gap of Monsoon :-
    • Definition : The absence of rainfall for 2 to 3 weeks after the monsoon bursting is called gap of monsoon.
    • Time : August/ September
  3. Retreating of Monsoon :-
    • Definition : The phenomenon of the return of monsoon is called retreating of monsoon.
    • Time in India : November/ Mid December
    • Time in Rajasthan : October/ November
  4. Kartik/ October Heat :-
    • Definition : The sudden rise in temperature for 1 or 2 weeks during the retreating monsoon is called Kartik/ October heat.

Global Events Affecting the Monsoon :-

  1. El-Nino :-
    • Meaning : It is a warm oceanic current.
    • Location : On the eastern coast of South Pacific Ocean (3° to 24° South latitude)
    • Time : Last week of December
    • Effect : Monsoon arrives late and is less effective.
    • Other names : Child of Christ, Oceanic Fever
  2. La-Nina :-
    • Meaning : It is a cold oceanic current.
    • Location : On the eastern coast of South Pacific Ocean (3° to 24° South latitude)
    • Time : Last week of December
    • Effect : Monsoon arrives on time and more effective.
    • Other name : Younger Sister of El-Nino

3. Autumn Season :-

  • Time : from October to November
  • Phenomena :-
    1. Retreating at Monsoon :-
      • Definition : The phenomenon of the return of monsoon is called retreating of monsoon.
      • Time in India : November/ Mid December
      • Time in Rajasthan : October/ November
    2. Kartik Heat :-
      • Definition : The sudden rise in temperature for 1 or 2 weeks during the retreating monsoon is called Kartik/ October heat.

4. Winter Season :-

  • Time : from December to February
  • Phenomena :
    1. Mawath :-
      • Definition : The rain that occurs in winter is called Mawath. Which comes from the Mediterranean Sea through western disturbance (jet stream).
      • Time : December to March
      • Affected area : North Western Rajasthan like- Sri Ganganagar, Hanumangarh, Bikaner
      • Main benefited crop : Rabi crops like- wheat
      • Contribution in annual rainfall : In Rajasthan, 90% of the total rainfall is contributed by monsoon and 10% by Mawath.
      • Mawath is called golden drops, because the crop most benefited by it is wheat.
      • Mawath (Winter monsoon) is called Mediterranean sea/ Temperate Zonal/ North-West monsoon.
    2. Cold Wave :-
      • Definition : The cold winds coming from the Himalayas during winter are called cold waves.
      • Time : The time of cold wave in Rajasthan is mainly January.
      • Affected areas : Churu (most), Sikar, Bikaner
      • Direction : The direction of cold wave in Rajasthan is from north-east to south-west.

Other Facts Related to Climate

Isohyet Line :-

  • The line joining the places with equal rainfall in the map/chart is called ‘Isohyet Line’.
  • Main Isohyet Lines of Rajasthan :-
    1. 25 cm Isohyet Line : It divides the desert into two parts. For example-
      1. Arid desert
      2. Semi-arid desert
    2. 40 cm Isohyet Line : This is the eastern boundary of the Western Desert, which divides Rajasthan into two equal parts.
    3. 50 cm Isohyet Line : It is situated on the Aravalli range, which separates the eastern plains and the western desert.

Isobar Line :-

  • The line joining the places with same air pressure in the map/chart is called ‘Isobar Line’.
  • Isobar Lines of Rajasthan :-
    • Isobar Lines in January : In Rajasthan, the temperature is low and air pressure is high in January, due to which two isobar lines are formed over Rajasthan. For example-
      1. 1018 mb Isobar Line :-
        • On this line the temperature is low and air pressure is high.
        • Extension : Bikaner, Churu, Sikar
      2. 1019 mb Isobar Line :-
        • On this line the temperature is high and air pressure is low.
        • Extension : Jaisalmer, Jodhpur, Pali, Rajsamand, Chittorgarh, Jhalawar
    • Isobar Lines in July : In Rajasthan, the temperature is high and air pressure is low in July, due to which four isobar lines are formed over Rajasthan. For example-
      1. 997 mb Isobar Line :-
        • Expansion : Sri Ganganagar, Bikaner, Jaisalmer
      2. 998 mb Isobar Line :-
        • Expansion : Barmer, Jodhpur, Nagaur, Churu
      3. 999 mb Isobar Line :-
        • Expansion : Jalore, Pali, Ajmer, Tonk, Sawai Madhopur
      4. 1000 mb Isobar Line :-
        • Expansion : Sirohi, Udaipur, Pratapgarh, Jhalawar

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