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Climate , Weather , Rainfall & Monsoon




  • Climate & Weather 
  • Factors which determined the climate
  • Climate of India
  • Monsoon Winds
  • The Salient Features of Tropical Monsoon climate
  • Features of the Monsoon 


            What is mean by Climate & Weather ?

                  Climate is one of the basic element in the natural environment . Climate will be for long period of time at any place.climate is average state of weather .
            Eg: Summer & winter (2 month - 3 month)
                   Wealth is day to day conditions of atmosphere (Short period ).Weather regard temperature , pressure , wind, Humidity (water vapour in air )& Rainfall .
            Eg: Rainfall will come or may not happen.

            Factors which determined the climate ?

            • latitude
            • Attitude
            • Distance from the sea
            • Wind
            • Position of mountain 


                  1.LATITUDE :

                             India lies between 8.4 N to 37 N degree latitudes. 23.30 N degree latitude tropic of cancer passes across the country.The parts of the country to the south of tropic of cancer being closer to the equator experience high temperature throughout the year.High temperature coz of tropic of cancer closer to equator.Warm temperature coz of tropic of cancer in north on other hand low temperature particularly in winter .
                  Eg:   During , Month of November . Delhi located 38 degree N exp 23 degree C. kanyakumari 8 degree N exp 32 degree C.

                  2.ATTITUDE :

                              Temperature decrease with increase altitude from the earth surface .Rate of 1 degree C of every 165 metres.from sea level.Places situated at high altitudes are cooler & lower altitudes are not cooler plains .(less temperature that make cooler , higher temp make heat )

                  Eg:   New Delhi situated in  plain region with altitude of 239 meters from sea level so 40.2 degree C during June month.Temperature of Simla is located in higher altitude 2,205 metres higher for sea level so 23.7 degree C in June month.

                  3.DISTANCE FROM THE SEA :

                        The places to the north of tropic of cancer experience continental climate .(whether summer is extremely hot , winter is extremely cold).Tropical south has 3 side of  Arabian sea , Indian ocean & Bay of Bengal so which gives equable temperature.

                  4.WIND :

                            when wind blow from sea to the land bring warm temperature.Wind blow across the land bring dry temperature.

                  Eg: 1. Westerly wind originate in Mediterranean sea, blow into Northwest India bring rain to Punjab & Haryana .
                  2.The tropical cyclone wind originate in Bay of  Bengal blows along east coast in India.It causes heavy loss to life & property.

                  what is mean by Jet streams ?
                                  Air currents (temp /pressure are different ) in the upper layers of atmosphere .Jet streams determined arrival & departure of winds in India.

                   5. POSITION OF MOUNTAIN :

                              The position of mountain plays vital /main role in determining climate of any place.

                  Eg: 1.Great Himalaya range in the north India obstruct the bitter cold winds from central Asia to India.
                  2.The Himalaya range intercepts the rain-bearing southwest monsoon .Winds forcing them to shed their moisture , resulting heavy rainfall in northeast & Indo-Gangetic plain.
                  3.The Aravalli range intercepts south west monsoon winds & western side of this range is desert receives very less rainfall.


                  1.Rainfall during summer
                  2.Winter Rainfall
                  3.Distribution of Rainfall heavy
                      a) Region of very heavy
                      b) Regions of heavy rainfall
                      c) Regions of moderate Rainfall
                      d) Regions of scanty  Rainfall


                  RAINFALL DURING SUMMER :

                                         The Annual Rainfall varies from about 1,187 Cm to less than 25 Cm .At Mawsynram a station 16 km west of Cherrapunji , state of Meghalaya receives 1,187 cm rainfall higher in the world .Less than 25 Cm rainfall is found in Thar Desert in Rajasthan .The erratic (not usual ) nature of Monsoon creates Havoc (Damage,Disaster )at time due to unprecedented (unequalled )rainfall .


                  Winter Rainfall :

                               The Bay of Bengal in October & Nov meets with the damp winds ( Moisture Air ) of Retreating Summer Monsoon ( Wind flow from land to sea Absorb moisture from Sea ) .This current curves round over the Bay of Bengal & Blows directly into the coast .

                  A). Wettest 
                  B) Most distributed weather of whole year (Mainly on Oct & November )

                       Heavy rains accommodation by stormy winds sweep over the coastal regions causing widespread damage to standing crops & Disorganising of transport.Similarly NAGAPATTINAM  receives an average of 100 cm out of its total 140 cm in the cold season .Rainfall increase in coast area than Interior .Decrease rapidly on land , so over the Mysore plateau in Karnataka receives only 3 to 4 cm .


                              Distribution of Rainfall is determine the two factor

                                a) Direction of Rain bearing wind (Rain flow from Bay of Bengal ) 

                                B) Position of the Mountain Ranges .

                   Due to these Factors

                  30% = 15 to 80 cm
                  40 % = 80 to 120 cm
                  20% = 120 to 180 cm
                  10 % = over 200 cm .

                  On the basis of amount of rainfall , Our country divided into 4 Rainfall regions 

                  1.Region of very heavy 

                  2.Regions of Heavy rainfall 

                  3.Region of moderate rainfall 

                  4. Regions of Scanty rainfall 

                  A) REGION OF VERY HEAVY :

                       Areas with over 300 cm of rain are the Southern Slopes of the Eastern Himalayas , Assam , Bay of Bengal & West Coast Region  Comprising the Konkan , Malabar Coast of Kerala .

                  B) REGIONS OF HEAVY RAINFALL :

                      Areas with Rainfall between 200 to 300 are the Middle Ganga valley , Western Ghats , Eastern Maharashtra , Madhya Pradesh , Orissa

                  C) REGION OF MODERATE RAINFALL :

                       Areas of 100 to 200 Cm of Rainfall are the upper Ganga valley , Eastern Rajasthan , Punjab , Southern Deccan Comprising the Plateau Regions karnataka , AP, TN .

                  D) REGIONS OF SCANTY RAINFALL :

                  Areas with less than 50 cm are the Northern parts of Kashmir , Western Rajasthan , Southern Punjab , Regions of Deccan in the Rain Shadow of the Western Ghats .

                  WHAT ARE THE CLIMATE IN INDIA  ?

                         In-spite of the great diversity ,variation in Indian climate , Topography (study a shape & features of surface of the earth). lends unity to India is fact of the monsoon .The word monsoon origin Arabic word "Mausim " meaning season. The term mausim used by seamen several centuries ago describe " system of altering winds over the Arabian sea .Blow of wind from southwest for 6 month from northwest for 6 month.

                  what is mean by monsoon winds ?
                     Wind blow direction completely reverse between summer and Winter ( for eg in Summer wind blow from north east , on same In winter wind blow from south west that is mean by monsoon winds ).Due to reverse monsoon winds , India experience "Tropical monsoon climate ".


                     The monsoon winds are classified into southwest monsoon & northeast monsoon on the basis of wind flow directions.Tropical monsoon climate caused due to differential heating of land and sea.The main features of Tropical monsoon winds "Alternation of seasons" which determine the climate of India .

                  What is mean by season ? 

                  SEASON :
                       On the basis of the monsoon variation the meteorologists (The specific scientific principle to explain atmospheric phenomena , understand & observe , Forecast ) recognise 4 district seasons .

                  • Summer (Mar- May )
                  • Southwest monsoon (June-Sep)
                  • Northeast monsoon (Oct-Nov)
                  • Winter (Dec-Feb)


                  1.SUMMER (Mar-May):

                      During summer seasons the sun rays are vertical over the tropic of cancer .The temperature is very high in the north part of India.At the same time north west India the day temperature be high as 45 degree C due to high temperature & low Pressure.Temperature is contrary to the southern parts of India has moderate weather conditions ,because of locations nearer to sea .Mean Max temperature varies from 26 degree to 30 degree C .Because of the atmosphere pressure conditions winds blow from south west to north east direction in Arabian sea & Bay of Bengal. They bring Pre-Monsoon showers to the West coastal areas during May Month.There are few thunder shower called "Mango showers" helps in Ripening of mangoes"along the coast of Kerala & Karnataka.Northwestern part of India also fell some local storms is called northwesters

                  WHAT IS MEAN BY LOO WINDS ?

                             Strong hot winds blow during daytime over Northern & Northwest parts of India is called Loo Winds .

                  WHAT IS MEAN BY TROPIC OF CANCER ?

                        Tropic of cancer referred as the northern tropic .Its the most northerly circle of latitude on the earth .At which sun may appear directly overhead even occur once per year.Northern Hemisphere is titled sun to it . In 5th April 2016, tropic of cancer lies at max extent of 23.43718 degree north of equator.

                  2. SOUTH WEST MONSOON (June - Sep ):

                     After summer season, Rainy season starts with on set of southwest monsoon.The high temperature gives low pressure & end of May, large area of low pressure is formed over the northwest part of the country.The oceans become cool & high pressure area develops over the oceans.we know that wind always blow from high pressure to low pressure.

                  What is mean by Moisture Laden Winds?

                       Moisture Laden winds blow from ocean towards the land of India.These wind blow from southeast directions.When the wind cross the equator deflected & blow as " South west monsoon ".is called moisture Laden winds.because it originated from Indian ocean.

                  What is mean by Monsoon Burst ?

                                 When south west monsoon originate from Indian ocean & approach the southern part of kerala give rain with violent thunder storms indicating on set of monsoon .is called monsoon Burst.Southwest monsoon normally divided into 2 branch ,because of Peninsular shape of the country.

                  • Arabian sea Branch
                  • Bay of Bengal Branch

                  ARABIAN SEA BRANCH :

                      Arabian sea brings heavier rainfall.Blowing from Arabian sea, The First part of wind strikes against the western Ghats.The moisture laden wind is forced to give Ascend the slopes(Rise , move, upward ) & condenses (Reduce the density)heavy rainfall to western coastal region.

                  Eg: 1.Mumbai gets a heavy rainfall of over 150 cm lies on the windward side (wind striking side of mountain) of western ghats.
                  2.While Pune gets less than 50 cm of rainfall as it lies on on leeward side (Rain shadow / other side of the mountain ). of the Western ghats
                  3.The second part of this wind blow through the Vindhya - Satpuraa ranges strikes against Rajmahah hills causes heavy rainfall in chotanagpur plateau region.
                  4. Third part of the wind moves towards Rajasthan Where Aravalli mountains stand parallel to directions of wind . so not strike against the mountain & not give rain to Rajasthan .This is the reason western Rajasthan remains Desert.Third part of wind reaches the Himachal pradesh combines with bay of Bengal .Get obstructed by the shiwalik hills & gives a good rainfall to the foot hills of this region .

                  what is mean by Rain shadow Region ?
                  An area receiving relatively less rainfall due to the Obstruction of mountains is called rain shadow region.

                  BAY OF BENGAL BRANCH :

                      Branch of monsoon blowing from the Bay of Bengal is Moisture bearing wind strikes against the Kasi , Garo, Jaintia Hills .It take sudden rise over the funnel shaped hills  causes heavy rainfall Mawsintram in India .A part of this branch gets deflected by the Himalayas & moves towards the west give rain to Gangetic plains.moves further to western wards it loses the moisture content gives scanty rainfall to punjab & Haryana .Tamil Nadu remains dry during his period because it rise in rain shadow area.of the Arabic sea & lies parallel to the Bay of Bengal Branch .

                  3. NORTH EAST MONSOON (Oct - Nov) :

                           The southwest monsoon begins from Northern Indian by Sep. Coz apparent movement towards "tropic of cancer" The landmass of Indian starts losing heat & decrease the temperature .Increase pressure develops in land & Decrease pressure over the sea .Wind blow from high pressure to low pressure that is land to sea it is called "cold dry wind " & gives no rainfall to land mass.But it crosses the bay of Bengal it absorbs Moisture & gives rainfall to Coramandel Coast . So, Tamil Nadu & AP gets more rainfall during winter. There are frequent cyclone formed in the Bay of Bengal cause damage to life & property along the coramondal region .

                  4. WINTER (Dec - Feb ):

                           During Winter , The sun is overhead in the " Tropic of Capricorn " .So land mass became cold in Northern part of India , temp remains below 21 degree C . No Obvious diff found in the day & Night temperature .In the mean time high temperature found in the north western part of India to prevalence of less pressure . In contrast , Less pressure forming in south India .Both in Arabia sea & Bay of Bengal .

                  what is mean by Retreating Wind ?

                      Wind flow from land to sea , which will not give rainfall , But wind absorb Moisture while crossing from Bay of Bengal . & gives winter rainfall to TN & AP  .

                  what are the Char of Retreating wind ?

                     During winter less pressure originates over the Mediterranean sea & travel east wards across Iran & Pakistan then reaches India.is called western disturbance .The Jet streams players dominant role bringing this disturbance in India. The western disturbance cause rainfall in Punjab, Hariyana , Himachal pradesh useful for cultivation of wheat brings snowfall in the hills of Jammu & Kashmir.

                         FEATURES OF THE MONSOON 

                  1. Uneven distribution of Rainfall during the year.

                  2. Influence of mountains 

                  3. Tropical cyclone

                  4. Erratic (Not usual ,Acting, moving / changing )  Nature of the Rainfall

                  5. Monsoon rains have great effect on the country's economy.


                       During June to September , the south west monsoon brings over 80% of the rainfall  over the country.The normal duration of southwest monsoon varies from two to four months. Normally   south-west monsoon withdraws  beginning of September month . Remaining parts of the country by the end of October or November.

                  2.INFLUENCE OF MOUNTAINS :

                       The rainfall is very much influenced by Orthographic features (Rain produced from the lifting of moisture air over a mountain ).Though the wind passes over Gujarat & Rajasthan, it brings very less rainfall due to the absence of mountains.Along the west coast, the winds strike the western ghats & bring heavy rainfall on the windward side.
                  Example :
                    1. The shillong plateau receives heavy rainfall (Annual rainfall at Cherrapunji 1,270 cm ).
                    2. While central part of the Assam valley , which situated in Lee ward side receives less rainfall .(Annual rainfall of Guahati 163.7 cm).

                  3.TROPICAL CYCLONE :

                        The intensity Distribution of rainfall are determined by a series of tropical depressions ( Low pressure system ).Tropical depression their origin near the northern part of Bay of Bengal  & Travel across the country in West & North -West Direction . On an Avg of eight (cyclonic depression) may pass from the Bay of Bengal into the land area between June to September .

                   What is mean by Cyclone ?

                         Cyclone is small but intense low-pressure system  in Arabia sea or in Bay of Bengal , which produce Violent winds & Heavy Rainfall .

                  4.ERRATIC (change , not usual )NATURE OF THE RAINFALL :

                           It is difficult to make any general statement describing the rainfall in particular state, coz same rainfall receive heavy rainfall in one season & may experience drought conditions in the next season .Some time beginning rainfall may delayed . There may be breaks in the monsoon rain during July & August . Rain disappears for a week /more . Monsoon may also withdraw earlier than usual or may persist longer than usual .


                       The prosperity of India depends on the success or failure of the monsoon . The slight variations in the directions of Rain - Bearing winds may convert normally well -watered areas into deserts .
                  Example :
                  1.Gujarat & The Decan Plateau are particularly liable to Drought.
                  2.Hydro electric power plants are affected severely in times of low rainfall .