Climatology

ClimatologyOrigin of the atmosphere on the earthStructure of atmosphereHeat BudgetAlbedoMovement of airStability and instabilityAdiabatic lapse rateTemperature InversionPrecipitation processes: evaporation- Humidity - condensation-cloudsTypes of cloudsTypes of rainfallPressure system of the worldPlanetary wind systemVariable windsTemperature decreases with increasing heightGHG gas absorb long wave terrestrial radiation transparent to insolation (short wave radiation)Heated from terrestrial radiation from earth surfaceTroposphereStructure of Atmosphere

Temperature increases with increasing heightOzone layer absorbs UV rays from Insolation StratosphereStructure of Atmosphere

Temperature decreases with increasing heightAbsence of GHG gasGoing away from Ozone layerMesosphereStructure of Atmosphere

Temperature increases with increasing heightGases are in ionic state extremely hotIonosphere -Imp for radio communication ThermosphereStructure of Atmosphere

Movement of airAdiabatic lapse rateBasic air movement

Temperature InversionEx. Of Temp Inversion - tropopauseTemperature Inversion

Ex. Cool winter nightEx. Valley inversionTemperature Inversion

EvaporationRelative HumidityAddition of moisture or reduction of moisture holding capacity of the air packet = rainfallAddition through evaporationReduction through upliftment of the airHumidityPrecipitation process

Condensation- cloudsTypes of clouds according to their height and shapeNimbus clouds give rainfallCumulonimbus cloud indication of instabilityCyclonic heavy rainfallPrecipitation process

Convectional rainfall

Orographic rainfallTypes of rainfallCyclonic rainfall

Frontal rainfallTypes of rainfallPressure system of the world

High pressure to low pressureCoriolis force clockwise in northern hemi and anti-clockwise in southern hemiTrade windsWesterliesPolar easterlies

Planetary wind system

Around tropopause, there is only one gradientWind accumulated above equator and rarified atmosphere above polesHP at the equator and LP at the poles

Upper tropospheric windsLPHPLPHPstrong coriolis force at tropopauseBecause friction is less - high speed - stronger the coriolis forceSo the deflection is 90 degreeSuch winds called geo-strophic windsGeo-strophic winds

EquatorPolesNorthern hemisphereGeostrophic deflect clockwisewest to eastIn southern Hemisphere: Anti-clockwise movementDeflect west to eastGeo-strophic winds

PolesPolesEquatorHPLPLP

Westerlies windsThe upper tropospheric winds / geo-strophic winds blow from west to east at the very high speed

Westerlies at poles to maintain the angular momentum- they meander => Rossby wavesRossby waves do not meander consistently, but follow a cycle = Index cycle

Rossby wavesIn westerlies, there are strong, narrow bands of high speed wind => Jet streamSpeed of Jet stream 300kmph

Jet streams

There are situated at the margins of meridional cells4 permanent Jet streams: 2 Polar Jet and 2 Sub-Tropical Westerly Jet STWJ

Jet streams location

STHPEq. LPSPLPPolar HighPermanent jet streamTemporary jet stream-TEJJet streams

Tibet plt. LPMascerene HighTropical Easterly JetSW Monsoon winds

Somali jet stream/ FindlaterPolar-night Jet Temporary Jet Streams

summerwinter

Polar night Jet streamSomali Jet streamJet stream embedded in westerlies (Rossby waves) at high latitude, cause pressure variabilityThats why they are called travelling depressionJet streams

Jet Stream travelling depressionsWeather of higher latitude is more complex than weather of equatorial or tropical regionsBecause tropical and equatorial region are heat surplus region thermal reasons play the dominant role. But higher latitude are heat deficit region dynamic reasons play dominant roleThese include localised + upper-tropospheric circulations (Rossby waves, Jet streams, temperate cyclones)

Weather of Mid and high latitudeThermally inducedBecause of high temperatureEx. LP at equatorConvectional rainfall at equatorUpliftment of warm airEx. LP at sub-polar LP beltFrontal rainfall

Dynamically inducedConditions for LP

Large extensive body of air-mass (1000sqkm)Height upto TropopauseAt particular height, one air mass will have uniform temperature and moisture across its widthAirmasses can be differentiate according to their temperature and moisture content

Air mass

Air mass acquired properties from the source regions land, marine, polar, arctic, Antarctic = give them identity. Ex. mP, cTExtensive homogeneous surface + longer stay (HP)

Air massAir masses do not stay at their source regions forever, they move out. While moving they came across other air masses.

Air masses

The relative difference between temperature and moisture decide their interaction with one anotherThe border/ meeting region of the two air-mass => Front

Front

Cold frontWarm front

If cold air mass move faster than the other than it will lift the warmer one upward => cold front the slope will be steep = there will be sudden up-liftment of the warm air = cumulonimbus clouds = cyclonic rain

Cold frontCold air mass

If warmer air mass is more active than cold front => warm front slope will be gentler = there wont be sudden up-liftment of warm air = uniform prolonged rain drizzle

Warm front

Fronts

Cold frontWarm frontCold frontWarm frontCold air masswarm air massCool air massAlso called as extra-tropical cyclone, travelling depressions, cold-core cyclone, wave cyclones

Frontal cyclone

Intense LP systemAir converges towards the centreIn Northern hemisphere convergence anti-clockwiseClosed isobars

Meaning of cycloneNormal isobar

Closed isobarIsobarThermally inducedBecause of high temperatureEx. LP at equatorConvectional rainfall at equatorUpliftment of warm airEx. LP at sub-polar LP beltFrontal rainfall

Dynamically inducedConditions for LPMovement of airmasses from their source regionThe warm and cold air mass face each otherA front is created between them Called Stationary front

Development of Frontal cyclone

Location of air massesCircular movementFormative stage of frontal cyclone

Cold air mass pushed the warm air massForced upliftment of warm air mass at the cold front =LP Two cold air mass convergence circular due to coriolis force

Development of Frontal cyclone

Interaction of air massesLP closed isobarsMature stage

One cold air mass climb over other cold air masswarm front is destroyedCalled occluded frontRapid change in temperature and pressureUnstable weather conditions

Occluded front

Frontolysis no great temperature difference between two cold air masses front dissipated LP reduced cyclone dissipated

Dissipation of frontal cyclone

Stationary frontFront

Occluded front

Frontolysis

Always west to east directionBecause influence of the Westerlies Gradual and predictable movement

Path of the temperate cyclone

Distribution of temperate cyclonesTemperate cyclonesHurricane N. AmericaTyphoon - ChinaLate summer Increased sea surface temperature = LP

Tropical cyclone

Convergence of air around LP zoneRising moist (wet) air => absolute instabilityCloud formation =more and more moisture latent heat of evaporation => cumulo nimbus cloud => cyclone

Tropical cyclone

Intensification of LPConverging air near water surfaceCirculating air rises above (coriolis force)Diverging air at the top of cycloneMature Tropical cyclone

At the centre of the cyclone eye of the tropical cyclone. It is a pressure defect. Because, at eye a narrow stream of wind descend = is HP at eyeAt the eye, there is clear sky.Beyond eye wall extreme low pressureEye of the tropical cyclone

Move swiftlyAlways east to westIt is fuelled by moisture so when cyclone is cut-off from sea and move towards land it starts weakening

Properties of tropical cyclones

Distribution of tropical cycloneTemperate cyclone30-40 degree latitudeDynamically inducedDue to frontal interactionFormed over large areaMove west to eastGradual movement predictable8-20 degree latitudeThermally inducedDue to increasing SSTSmall areaMove east to westSwift movement- difficult to predict pathTropical cyclonecomparisonTemperate cycloneWind speed 40-50 kmphPressure gradient 980 mbPowerful on landAffect mainlandMore time to dissipateWind speed >120 kmphPressure gradient loss in fishing business

El-Nino yearDown-wellingDown-wellingUpwellingUpwellingEl-Nino bring drought condition in Indonesia as well forest fireIt is responsible for weak monsoon in IndiaImplications of El-Nino

Association of El- Nino or Western Pacific Pool with Indian Monsoon There can be other atmospheric cells associated with Western Pacific poolStill undiscoveredImplications of El-Nino on Indian MonsoonMascarene HighWestern pacific PoolHPLPLPWith global warming there will be increasing number of El-Nino eventsIt is a global phenomenon. Though happening in limited area, it may have wider implication over the globe

Global Implications of El-Nino

Intensification of walker cellStrong west pacific poolHeavy rainfall flood condition in Northern Australia good monsoon in IndiaDrought in AtacamaVery good fishing business at Peruvian coast price crash

La-NinaThunderstormTornadoEL-Nino La-Ninaimplications

Climatic regions of the worldEquatorial regionTropical monsoonSavannahSteppeHot desertContinental deserts

7) Mediterranean climate8) China type9) British type10) Laurentian type11) Taiga12) Tundra

Climatic regions of the worldEquatorial regions in the world

5-10 degree latitudeSame season (weather) throughout the yearDirect sunlight heat surplus LP condition every day rising of moist air advection rain every eveningHot-wet climate

Equatorial climate

Dense forest rainforest lungs of the earthHigh biodiversityTall trees (Abony, Rosewood, mahogany, rubber) epiphytes But not good for lumbering hardwood high diversity loading-unloading very difficult

Equatorial climateAmazon rainforest is being cleared for rubber plantation, oil exploration Yasuni national park in Ecuador cleared for oil extraction biodiversity is more than entire north America - 2 un-contacted tribes Rainforest of Indonesia- cleared for oil-palm cultivation

Equatorial climate

Equatorial climatenot good for habitation hot and moist climateHigh incidents of malaria and diseases

CountryPrimitive tribeCongoPigmyMalaysiaSemang, Orang AsliPhilippinesOrang AkitaBorneoDayaksEquatorial climatePrelims2013Q. Which of the following is/are characteristics of equatorial forests?Presence of tall, closely set trees with crowns forming continuous canopyCo-existence of a large number of speciesPresence of numerous variety of epiphytesUPSCQuestionPrelims20131 only2 an 31 and 31,2 and 3

Ans.d)UPSCQuestion

Sub-tropical HP beltOff-shore trade winds by the time rain bearing wind reach from east to west they become dry so no rain on western coast in Northern hemisphere and southern hemisphere

Tropical desertSTHPSTHPSTHPSTHP

desiccating effect of cold oceanic current on western coast of continents

Tropical desert

Arid-dry climate, scanty rainfall, water deficit Vegetation Xerophytic Low population Maghreb region high povertyTauregs of Sahara, Beduins of Arabia Hottentots of Kalahari desert

Tropical desert

Interior of large landRainfall bearing winds cannot reach thereLeeward side of the mountainAridity (but no sand dunes)High annual temp range

Continental desertChina

South AmericaContinental desertsTIEN SHANALTUN SHANANDES RangeNegev DesertKalahari DesertNamib DesertAtacama DesertTakla MakanRub al-KhaliDast-e-kavir Dast-e-lutNubian DesertPatagonian DesertGreat Sandy DesertSimpson Desert Great Victorian Desert

Deserts to locateIt is also called savannah, the park land topography or big game countryLocated between rain forest and hot desert

Tropical grassland

Llanos, Campos S.Ame

Savannah -AfricaTropical GrasslandsCamposc

Moderate rainfall clear dry-wet seasonTall grass elephant grass, scanty large trees, grass-fire in dry season way of controlling treesLarge carnivorous animals

Tropical grassland

Acacia tress with broad trunks baoab trees and bottle treesTo store waterGrass long roots, remain dormant in dry periodAustralia Mallee, Mulga, Spinifex grasses

Tropical grassland

Tribes = Masai tribe (kenya) Pastoralist Hausa and Aibo tribes of Nigeria

Tropical GrasslandsPrelims2012Q. Which one of the following characteristics of climate of Tropical Savannah region?Rainfall throughout the yearRainfall in winter onlyAn extremely short dry seasonA definite dry and wet season

Ans. D)UPSCQuestion

ContinentsNames North AmericaPrairiesSouth AmericaPampasCentral AsiaSteppeSouth AfricaVeldtAustraliaDownsTemperate grasslands

Cooler and wetter than Savannah Under westerliesPerfect grassland no trees Grass is very nutritious

Temperate grasslandsTemperate grasslands entirely converted into agriculture. Prairies: Truck-farming large acres of farmlands extensive use of machinery- High productivity per person

Truck-farming

Wheat, cotton and Maize cultivationUSA:Prairies: maize is fed to animals fattening slaughter house near great lake region

Prairies, North America

Pustaz in hungaryWheat bowl of the worldBlack EarthSugar from sugar beet

Steppe, AsiaLivestock ranchingAlfalfa nutrious grassArgentina wheat exportsBuenos Aires and Montevideo - Meat and dairy exports

Pampas, South America

Australia: sheep rearing, meatNew Zealand: Canterbury plainsSheep rearingDowns, AustraliaDOWNSVeldt (Dutch word) = fieldBasins of Orange river and river Limpopo sheep rearing, agora goatWool production Veldt, Africa

Orange riverLimpopo riverIndia, Thailand, Cambodia, Myanmar, Laos, Vietnam, Northern tip off AustraliaEastern Brazil Gulf of Guinea coast and around horn of Africa in Africa

Tropical Monsoon

On shore trade wind seasonal reversal of windsDuring summer, sun move northward With sun, LP ITCZ also move Thus, entire wind system shift northward

Tropical Monsoon

The region which was under northern trade winds, come under southern trade windsNorthern trade winds blow north to south, while southern trade winds blow south to northit seems reversal of winds in the region

Tropical Monsoon

ITCZITCZ

Distinct wet and dry season rainfall in confined to 4 months vulnerable to drought and floodSimilar to savannah but wetter than savannah

Tropical Monsoon

Tropical deciduous forest distinct autumn season shedding of trees Trees: Indian subcontinent Sal, Teak (Myanmar Teak)Hardwood

Tropical Monsoon

Intensive agriculture, subsistence farmingHigh population density, small land holdingHigh productivity per acre per person lowCrops: rice, sugarcane, jute, cotton, indigo, spices

Tropical Monsoon

Shifting cultivation/ slash and burn cultivation/ Jhum cultivationforests are cut, burnt and cultivated.When soil fertility began to decline, the land is abandoned, and a new patch of forest is burnt. By the time abandoned land regenerated for several years until the next round of cultivation.

Tropical MonsoonagainstDeforestation higher run-off of rain water in hilly areas -Water scarcity during non-rainy days loss of biodiversity

Jhum uses natural cycle of forest regeneration (6-10 years)Cause temporary loss of forest patches No use chemical fertilizers or pesticides + diversified crops

favourJhum cultivationthe dry the cut trees are dried under the sun- burn the trees ashes of the burnt trees (Potash) replenish the soil nutrientsThe regenerating forest provides forest produce to the peopleSettled agriculture- monoculture plantation of pineapple, rubber and oil palm cause permanent loss of forestOnce monoculture adopted with chemical inputs, the same land cannot be converted into natural forest

Jhum cultivationCountryTerm for shifting cultivationMalaysiaLadangMyanmarTaungyaThailandTamraiPhilippinesCainginJavaHumahShri LankaChenaAfricaMilpaDifferent names of shifting cultivation