geogra l5 2

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Sand-bar islandsCoral Islands

Types of Islands

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formation

• Symbiotic relationshipbetween coral polypsand xooxanthalae

•

Sunlight –depth 50 m• Temp – 25-27 deg

• Salinity –

• !alm" circulating

nutrient rich water• #ot at mouth of ri$er

conditions

!oral reef

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Coral bleaching

• !oral polyps expelxooxanthalae understress condition

•

%lobal warming• &'one depletion

• &cean acidi(cation

• Sedimentation

• )arine pollution• diseases

Reasons for

bleaching

!oral reef

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•

*ringing reef– barrier reef-atoll

• Subsidence

theory of+arwin

• Standstilltheory of)urray

*ormation of coral reef

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,ori'ontal)otion of &cean water

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wavesOcean currents

,ori'ontal motion of ocean water

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tidesSpring-neap tide

Tides

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UpwellingDown-welling

p-welling and down-welling

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Temperature of the ocean

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• )ain energy source - Insolation

• &ceans play important role in energyand temperature regulation on earth"due to speci(c heat of the water

• .$erage temperature of ocean / -5degree !elsius

• ut a$erage surface temperature ofocean water / 25 degree

Temperature of &cean

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• 1atitudinal $ariation

• It decreases fromeuator to poles

• ut highesttemperature is notat the euator butat the tropics

• 3eason4 high

rainfall" cloud co$erhigh albedo6reection ofsunrays8

Temperature 9attern of the &cean

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•,emispheric$ariation

•#orthernhemisphere

warmer thansouthern

•3eason4 largeland mass in

northernhemisphere –high energy

Temperature pattern of the &ceans

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• :nclosed seas

• )arginal seas oftropics warmerthan open &cean

; marginal seas oftemperate regioncooler than openseas

• 3eason4 lessmixing of water


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• &cean

currents• <arm

ocean

current –warminge=ect

• !old ocean

currentcoolinge=ect


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• p-welling and

dow-welling• pwelling bring

cool water from

depth –lowerdown the surfacetemp


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• +own-welling– piling up ofwarm water –

increase thetemp


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•

)ax temp of dayand min temp ofnight time

• Tropical waterhigher diurnalrange thaneuatorialwaters

• ecause",eating andcooling of waterrapid underclear s>y

+iurnal range of temperature

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•

igger thesi'e of ocean-better mixingof water and

heat• 1ower annual

range

•

9aci(c ocean –lower annualrange than.tlantic &cean

.nnual range of temperature

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9relims2007

?@ !onsider thefollowing statements4

A8 .nnual range oftemperature is

greater in 9aci(cocean than in.tlantic ocean

28 .nnual range oftemperature is

greater in northern

9S!

?uestion

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9relims2007

<hich of the statementis correctB

a8 A only

b8 2 only

c8 oth A and 2

d8 #either A or 2

.ns@ 8

9aci(c &cean – better

9S!

?uestion

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Ast layer – upto 500m

20-25 deg !8

2nd layer –thermocline 500-A000m

th layer – cold layer–beyond A000m

Certical distribution of temperature

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• Temp decreases withincreasing depth

• rate of decrement is

rapid at euator –tropics than towardspoles

• Ast layer – permanent

in Tropics–temperate only insummer

Certical distribution of temperature

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Temperature of the ocean

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• .mount of salt found in A000 gm ofwater

• #acl 7DE8" )g!l2 AAE8" )gS&F@5E8" !aS&F 2@5E8

• #a and !l has high residual time inocean water – $ery gradual remo$al –

thatGs why" they remain in thehighest proportion

Salinity of &cean water

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• Irrespecti$e of absolute salinity of thewater" the proportion of the saltremain same in all parts of the

oceans

• .mount of addition or extraction offresh water compared to salt content

in the &cean water decides absolutesalinity of the &ceans@

Salt udget

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• Sediments carried by ri$ers

• Submarine $olcanism at )&3

•

!hemical reaction between roc>s ofgeothermal $ent of $olcano and coldwater

• :rosion of oceanic roc>s

Sources of salts in ocean water

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• 9hysical remo$al – wa$es brea> atthe beaches" salt-spray

• iological remo$al – marine life formsextract calcium from sea water fortheir bones

3emo$al of Salts in &cean water

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• .ddition of fresh water /H 3ainfall"inow of large ri$er" melting ofglacier /H less salinity

• 3eduction of fresh water /H increasein temperature" high e$aporation"windy wind accelerate the

e$aporation8

Cariation in salinity

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• Standard salinity of ocean water is /5@5 ppt – salinity of .tlantic &cean

• +ead Sea 50 salinity8" 1a>e $anF008" 1a>e rmia

• )an seldom drowned in sea withhigh salinity

• ecause" high salinity / high density

Salinity of the oceans

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• Salinity goesdecrease fromeuator to poles

• ut highest

salinity is not atthe euator /because highrainfall" cloud

co$er• ,ighest salinity

is at tropics

9attern in $ariation of salinity

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• #orthern

hemisphere –warmer – highe$aporation –saline

• ut in southern9aci(c- roaringF0" furious 50and shrin>ing 0screaming 70 –$ery fast winds

• ,igh e$aporation

/H high salinity

9attern in $ariation of salinity

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• Ast - &cean

currents• warm ocean

current li>e"

highe$aporation

• !old currentled to p-

welling4 coolerwater fromdepth come atthe surface /H

low salinity

1ocal Cariations in Salinity

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• 2nd - :nclosed

seas• low latitude -

warmer than open

sea- high salinity• :x@ )editerranean

Sea" 3ed sea

• high latitude-

cooler than opensea – low salinity

• :x@ altic Sea


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• th – inow of

large ri$ers• %anga –

rahmaputra ow

into ay of engal• ay of engal less

saline than.rabian sea


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Mississippi in GofMe!ico

"mu dar#a$ S#r

dar#a to "ral sea

3i$ers inow to the seas

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%lac& sea'ersian gulf

3i$ers inow to the seas

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• Fth – glaciers

• altic sea recei$efresh water from

melting of glaciers– low salinity


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• Salinity decreases with increasingdepth

• Temp of water decreases

• +ensity of water increases

• Salinity increases density –watersin>s

• Saline water free'e slowly comparedto pure water

Certical pattern of salinity

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• :uator – salinity increases withdepth upto some layer –thandecreases with depth

• eyond euator – salinity decreaseswith depth

• Certical salinity $ariation of oceans is

complicated• #o uniform layering

Certical pattern of salinity

f

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Temperature of oceanwater

$ariations

Salinity of ocean water

Salt budget

$ariations

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!limatology

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• :arly atmospherehas , and ,e in

abundance-lighter gasesescaped

• +uring early life of

the earth –extensi$e$olcanism-degassing@ #" S"<ater Capour".rgon and !&2came out

&rigin of the .tmosphere on :arth

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• <ater $apour

condensed –clouds – rainfall–washed outbul> of the !&2

into &ceans@ !o2/ 0@0E

• &xygen – fromanaerobicrespiration ofbacteria li>e"!ynobacteria

&rigin of the .tmosphere on :arth

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Gas 'ropor

tion(itrogen 7DEO!#gen 2AE"rgon 0@JECarbon

dio!ide

0@0E

(eon 0@00AD

E

)elium 0@0000

9roportion of gases

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• #" &" , and .rgon are permanentgases

• <ater $apour" !o2" o'one -H $ariable

gases" %,%

• #" .rgon – inert gases

• .tmospheric gases- no chemicalinteraction among them

• They donGt lose their properties

• They act as a single uni(ed gas

9roportion of gases

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Structure of atmosphere

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• J0E of

atmospherewithin 2 >m

• Tropopause /,eight D >m atpoles" AD >m ateuator

• .t euator

cumulonimbusclouds

Troposphere

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• Temperature

decrease as heightincreases

• Transparent toinsolation

shortwa$e8• ,eated by

terrestrial radiation

longwa$e8• %,%s absorbs long

wa$e terrestrialradiation

%reenhouse e=ect in troposphere

?uestio

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9relims

20A2

?@ normally" the temperaturedecreases with increase in

height from the earthGssurface" because"

A@ .tmosphere can be

heated upward only fromearthGs surface

2@ There is more moisture in

upper atmosphere@ The air is less dense in

upper atmosphere

9S!

?uestion

?uestio

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9relims

20A2

a8 A only

b8 2 and

c8 A and

d8 A"2 and

.ns@ !8

1ess dense / lessamount of %,%s / lowtemp

9S!

?uestion

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• Temperatureincreases withheight

•

ecause ofthe presenceof o'one layer

• &'one

absorbs Crays fromisolation

stratosphere

?uestio

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9relims

20AA

?@ The Ket aircrafts y $eryeasily and smoothly in lower

stratosphere@ <hyBA@ There are no clouds or

water $apour in lower

stratosphere2@ There are no $ertical

winds in lower

stratosphere

.ns@ A in wrong" 2 is correct

9S!

?uestion

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•

.bsence of %,%s• Temperature

decreases withheight

)esosphere

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)esospheric

clouds• !louds $isible

at highlatitudes

• +uring summerseason

• !ondensation

of mixture ofmeteoric dustand somemoisture

#octilucent clouds

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• Temperatureincrease withheight

•

%ases in ionic state– trap insolation –extremely hot

• ut ions are highly

dispersed• p to D00 >m from

earth

Thermosphere

* D0> t

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• *rom D0>m toF0 >m

• #umber ofionic layers

• seful inradio-

communication

Ionosphere

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• ,igh energy

sunrays andcosmic raysbrea> the atomsof air molecules –

become ionised;$e charged8

• eha$e as free

particles• .t night time"

only cosmic raysioni'ation -wea>

Ionosphere

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la#

ers

heigh

t

+re,u

enc#

'rese

nce

format

ion+ 0-

J0>m1* +ay-

timeSolarradiation

: JJ-A0>m

)*",*

+ay-time

C with#molecule

* A50-D0>m

)*",*

+ayLnight

% HF00> )*" +ay L

1ayers of Ionosphere

? . l i : thG ?uestio

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9relims

20AA

?@ . layer in :arthGsatmosphere called

ionosphere facilitates radiocommunication@ <hyB

A@ 9resence of o'one cause

reection of radio wa$esto earth

2@ 3adio wa$es has long

wa$elength

oth statements are wrong

9S!

?uestion

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• eyond F0 >m

• ,ighly rari(edatmosphere

• Cery high

temperature-but di=erentfrom airtemperature-

because noexistence of air-temp canGt befelt

:xosphere

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• %lowing lightsat mid-nightsat high

latitudes• .t height of

exosphere andmagnetospher

e

.urora

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• sun emit solarwind6storm fromits corona

• Solar wind

consist of plasmafree electronsand ;$e ions8

• Interaction of

solar wind withearthGsmagnetosphere-disturbance

.urora

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• !ollision of charged

particlesisoni'ation8 inmagnetosphere

• Ionised particles

emit light –releaseenergy

• charged particlesinteract with

geomagnetic (eldlines

• Thus" $isible onhigh latitudes

.uroras

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• The a$eragetemperature of theearth A5 degree

• :arth maintains inuxand out-ux of theenergy" but out-ux isnot immediate" it haslong time gap@ That is

why" the temperatureis maintained@

,eat budget

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• *irst 5Eabsorbed by&'one layer

• Then A5Eby cloud

co$er• &nly 50E

energyreached to

the earthsurface

,eat budget - Incoming

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• 20E is lost in

latent heat ofe$aporationA0E lost insensible heat

temperature ofthe body8

• A5E absorbed

by %,%s• 3emaining 5E

was released inthe space

,eat budget - outgoing

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• 3atio between thetotal solar radiationfalling upon asurface and theamount reected

• 3epresents as E

• :arthGs a$g@ .lbedo

/ 5E• 1owest- dar> soil

• highest - snowfall

.lbedo

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surface "lbedo*resh

snow

D0E-J0E

+esert 5-F5E

%rasses 2E!rops A5E

ri > - A -2

.lbedo - table

? <hich one of the following ?uestio

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9relims

20A0

?@ <hich one of the followingreect bac> more sunlight as

compared to other threeBa8 sandy desert

b8 9addy crops

c8 1and co$ered with freshsnow

d8 9rairie land

.ns@ !8

9S!

?n

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)ori*ontal

•

when there is pressuregradient

• from high pressure tolow pressure /Had$ection

•

when air get warm"gets expands"becomes lighter /Hmo$e upwards /Hcon$ection

vertical

)o$ement of air

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• <hen air gets

hotter thansurrounding air" itrises upward

• If it has moisture -latent heat ofcondensation –more heated – will

go up - formclouds -can bringrainfall /instability

Certical mo$ement of air - instability

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• <hen air is coolerthan surrounding –it cannot mo$eupward

• sin>ing air

• atmosphericstability or anti-

cyclonic condition• ,igh pressure on

ground

Certical mo$ement of air - stability

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1ow pressure – ,igh pressure

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• The rate at which airpac>et cools whilerising

• .$g adiabatic lapserate is @F degree6>m

• That is air pac>etgets cool by @Fdegree afterco$ering one >mupward

.diabatic lapse rate

8/17/2019 geogra l5 2


• if air pac>et has highmoisture content- notget cool so fast@

• Its adiabatic lapse

rate M@F degree6>mN F degree6>m /H<.13

• <et air can reachhigher distances withlow lapse rate /Hcreate instability

<et adiabatic lapse rate

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• If air pac>et is dry"

it does not ha$emuch moisture" itwill get cool $eryfast@ )ore than@F degree6>m –li>e" A0degree6>m@

•

+ry air createstable condition

+ry .diabatic 1apse rate

!onditions of stability and

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situation condition

!onditionalstability

when wet.13M normal

.13 M dry .13.bsolute

stability

when normal

.13M wet .13M +ry .13

!onditions of stability andInstability

increasingi

8/17/2019 geogra l5 2


increasingheight

temperature of airdecreasing"

but re$erseis

happenedthan it iscalled

tem eratur

Temperature In$ersion

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• Ast

• .t Tropopause– temperaturestartsincreasing

from here

• So air pac>etreach till here"

start mo$ingdownwards

:x@ &f temperature In$ersion

f i

8/17/2019 geogra l5 2


• 2nd

• . cool winternight" the airabo$e the coldsurface gets cool@

• ut the air layerabo$e that coollayer is till

warmer@ Then" bygoing upward" airdoes not getcooler but warmer


&f i

8/17/2019 geogra l5 2


• th

• Calley in$ersion• winter – cool air

descends to$alley

• plift the warmair of $alley

• +escending

cool air-damage crops-frost


Implications of temperature

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+ormation

of fog

arm air cooled

b# cold airbelow .condensation .

tin# waterdroplets- lowvisibilit#

*ormation offrost

<ater moisturefro'en withcontact cold

surface- dama e

Implications of temperaturein$ersion

? <hat do you?uestio

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mains20A

?@ <hat do youunderstand by

phenomenon ofOtemperature in$ersionP

in meteorologyB ,owdoes it a=ect weatherand habitants of the

placeB 58

9S!

n

! d ti f t d l t

8/17/2019 geogra l5 2


Condensation ofwater droplet Result

.t heights !louds

.t lower le$el *og

on the cold

surface

+ew

drop Turn into ice

crystal in extreme

*rost

!ondensation of water droplets

3 f f ti f f

8/17/2019 geogra l5 2


"dvection

Moving of warmair over cold

3adiat

ion

<inter nights –

loss of heat dueto terrestial

radiation – coldsurface@ )o$ing of

warm air o$er

3eason for formation of fog

+ i l l f i ibilit

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+ecreasing le$el of $isibility

i

8/17/2019 geogra l5 2


fog

•

<ater dropletcondensed around adust particle

• It reduces the$isibility" damage thecrops

• <ater droplet

condensed around aparticle of pollutant"li>e S&2

• 3educe $isibility ;

health ha'ard

smog

comparison

i

8/17/2019 geogra l5 2


Smog• It occurs in warm" dry

and sunny climate

• )ixture unsaturated

hydrocarbons andnitrogen oxides #&28in presence ofsunlight

•

Its components areo'one" nitric oxide"acrolein" andformaldehyde andperoxyacetyl nitrate

9.#8@

'hotochemical smog

comparison

• It occurs in cool humidclimate

• It is a mixture ofsmo>e" fog andsulphur dioxide S&28@

?@ 9hotochemical smog is ?uestio

8/17/2019 geogra l5 2


9relims

20A

? gresultant of reaction among

a8 #&2" & and peroxyacetylnitrate in the presence ofsunlight

b8 !&2" &2 and peroxyacetyl

nitrate in the presence ofsunlight

c8 !&"!&2 and #&2 at low

temperatured8 ,igh concentration of #&2"

& and !& in the e$ening

9S!

n

9hotochemical smog4?uestio

8/17/2019 geogra l5 2


9relims

20A

9hotochemical smog4

#&2" &'one ; sunlight

.ns@ .8

9S!

n

Structure of

8/17/2019 geogra l5 2


atmosphere

Certical )o$ement ofair

.diabatic lapse rate Temperature in$ersion

and its e=ectsfog

precipitation

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e$aporationprecipitation

:$aporation

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A8 ,igh temperature

28 19 conditions

8 *ast mo$ing wind• <ater $apour

e$aporate from thewater body

• :$aporation addsmoisture in the air

:$aporation

,umidity

8/17/2019 geogra l5 2


"bsolute )umidit#

• <eight of water$apour in unit $olumeof moist air

• <eight of water$apour per unit weightof dry air

Speci/c )umidit#

,umidity

9recipitation

8/17/2019 geogra l5 2


• 9recipitation – whenair is saturated withwater $apour and anyextra addition result

in precipitation3elati$e ,umidity4

• .mount of water$apour present in air

– to amount of water$apour reuired forsaturation

• 9recipitationdepends upontemperature andmoisture content ofthe air

• ,ot air – saturationreach with more

moisture contentthan cold air

9recipitation

Types of clouds

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Types of clouds

Types of rainfall

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Convectional rainfall

Orographic rainfall

Types of rainfall

Types of rainfall

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C#clonic rainfall

+rontal rainfall

Types of rainfall

9ressure system of the world

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• :ntire earth is di$ided into F large pressurebelts

• In reality" belts are not continuous butpoc>ets of low and high pressure@

• ut pressure can be created throughthermal or dynamic reasons

• Thermal4 high temperature/H 19" low

temperature /H ,9• +ynamic4 air rises /H 19" air descends /H

,9



8/17/2019 geogra l5 2


• F belts4

• euatorial lowpressure belt

• sub-tropical

high pressurebelt

• sub-polar lowpressure belt

• 9olar ,ighpressure area


:uatorial 19 belt

8/17/2019 geogra l5 2


:uatorial 19 belt

• !onstant insolation• .ir gets warm -19

• .ir mo$e upward

-H cloud formation-H instability -Hrain in the e$eningdaily

• !umulonimbusclouds

• !on$ectional

rainfall

:uatorial 19 belt

8/17/2019 geogra l5 2


:uatorial 19 belt

• .bsence ofad$ection of air

• elt of calm 6

+oldrum• ecause light"

feeble winds -calm region

Sub tropical ,9 belt ST,98

8/17/2019 geogra l5 2


• The air abo$e

euator mo$etowards pole" butcoriolis force - theirpath get deected@

•

The length of pathincreases@ Theirenergy reduced inmid-path -cooled@

air subside near 0-F0 deg latitude@

Sub-tropical ,9 belt ST,98

Sub tropical ,9 belt ST,98

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• .s descending air

– ,9• +ynamically

induced ,9

• !alled QhorselatitudeG

Sub-tropical ,9 belt ST,98

Sub polar 19 belt S9198

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• *rom the pole" cold

winds mo$etowards euator

• The both warmand cold winds

collide" the warmerwinds from ST,9rise abo$e the coldpolar winds

•

This rising ofwarmer wind near50-0 degreecreate 19

Sub-polar 19 belt S9198

9olar high

8/17/2019 geogra l5 2


• .ir risen at

S919"descends atpoles

• ,igh pressure

conditions• Thermally

induced

9olar high

<ind system of the world

8/17/2019 geogra l5 2



9lanetary winds

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• winds blowing at

the same directionthroughout the year

• co$er largedistances@

• ,ori'ontalmo$ement"9ressure beltsystem pro$ide

them the pressuregradient

• !orilis force modifytheir direction

9lanetary winds

• The winds mo$eTrade winds

8/17/2019 geogra l5 2


• The winds mo$etowards euatorial

low pressure /IT!R

• IT!R – intertropicalcon$ergence'one" where windcon$erges

•

Their direction iseast to west dueto coriolis force

Trade winds

Tropical deserts and trade winds

8/17/2019 geogra l5 2


• Tropical

easterlies ows–east to west

• <ind becomesdry when they

reaches thewestern coast ofthe continents

• &= –shore trade

winds• Trade wind

deserts

Tropical deserts and trade winds

Tropical desert and cold currents

8/17/2019 geogra l5 2


•

2nd• !old currents

pro$idedesiccating

e=ect to tradewind deserts

• !old current

ow onwesternmargins ofcontinents

Tropical desert and cold currents

?@ )aKor hot deserts in ?uestion

8/17/2019 geogra l5 2


)ains20A

Knorthern hemisphere

are located between20-0 degree #orthlatitudes and on thewestern side of thecontinents@ <hyB A08

9S!

n

<esterlies

8/17/2019 geogra l5 2


• *rom west to east

• *rom ST,9 to S919

<esterlies

<esterlies

8/17/2019 geogra l5 2


• *rom west to east

•

*rom ST,9 toS919

• 1ess landmass insouthern

hemisphere• *ast owing

winds in the opensea

•

3oaring F0s"furious 50s"shrin>ing 0s andscreaming 70s

<esterlies

?@ <esterlies in southernhemisphere are stronger and

?uestion

8/17/2019 geogra l5 2


9relims

20AA

hemisphere are stronger andpersistent than northern

hemisphere@ <hyB

A@ Southern hemisphere hasless landmass as compared

to northern hemisphere2@ !oriolis force is higher in

southern hemisphere ascompared to northernhemisphere

.ns@ A is correct" 2 is wrong

9S!

n

9olar :asterlies

8/17/2019 geogra l5 2


• *rom east towest

• *rom poles to

S919

9olar :asterlies

.pparent mo$ement of the sun

8/17/2019 geogra l5 2


Summer

inter

.pparent mo$ement of the sun

mo$ement of the pressure system

8/17/2019 geogra l5 2


Summer

inter

mo$ement of the pressure system


8/17/2019 geogra l5 2



Seasonal winds

8/17/2019 geogra l5 2


• )onsoon winds4

seasonal re$ersalof winds

• *eature oftropical latitude

• In winter – tradewind blows northto south" insummer – trade

wind blows southto north but inlimited area

Seasonal winds

)onson winds

8/17/2019 geogra l5 2


• +ue to apparentnorthwardmo$ement of thesun in summer@

Thus" the IT!R 198also mo$es upward

• Thus" the area whichwas under northerntrade winds inwinter" will come

under southern tradewinds in the summer

)onson winds


8/17/2019 geogra l5 2



1ocal winds 4 mountains winds

8/17/2019 geogra l5 2


Cold wind

countr#

wind

%reece

%ragale

Italy Tremonta

Mountains

ind

.lps *ohn

3oc>ies

!hinoo>

.ndes Ron

arm winds

oca ds ou a s ds

1ocal winds 4 land

8/17/2019 geogra l5 2


Cold wind0 land

• ,9 condition in winter• +i$ergence of cold air

• Siberia – uran

• !anada - li''ard

desert

inds

Sahara Sirocco

:gypt Uhamsin

1ibya %ibli

arm wind0 desert

1ocal winds 4 land

1ocal winds4 India

8/17/2019 geogra l5 2


summer

• ,ot-dusty wind / QlooG

states ind

ihar"

<".ssam

Ualbais

ha>hi

U# losso

mshower

U3 )ango

're-monsoonthunderstorm

1ocal winds4 India


8/17/2019 geogra l5 2


y

)ountain bree'e

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• +uring night

time4 top getscooler than$alley / ,9"$alley /19

• <ind mo$e hill-top to $alley /Hmountain bree'e

• .griculture –

frost bite" chill inhabitation in the$alley

• +uring dayCalley bree'e

8/17/2019 geogra l5 2


+uring daytime4 top

gets warmerthan $alley/ 19" $alley/ ,9

• So windmo$es from$alley to the

top /H$alleybree'e

y


8/17/2019 geogra l5 2


y

1and bree'es

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•

+i=erentialcooling of landand water

• +uring night4

• land cooler /,9"

• water /19

• <ind mo$e land

to water /H landbree'e

Sea-bree'e

8/17/2019 geogra l5 2


• +uring day time4• land gets warmer

/H19 " water /,9

•

<ind mo$e fromwater to land /Hsea bree'e

9ressure belts of theworld

8/17/2019 geogra l5 2


world

9lanetary wind systemCariable winds

Seasonal" local winds)ountain- $alley bree'e

1and-sea bree'e

• .roundpper tropospheric winds

8/17/2019 geogra l5 2


.roundtropopause" there

is only onegradient

• <ind accumulatedabo$e euatorand rari(edatmosphere abo$epoles

•

,9 at the euatorand 19 at thepoles

pp p p

%eo-strophic winds

8/17/2019 geogra l5 2


• strong coriolis

force attropopause

• ecause friction isless - high speed -

stronger thecoriolis force

• So the deectionis J0 degree

• Such winds calledgeo-strophicwinds

p

<esterlies winds

8/17/2019 geogra l5 2


• The upper

tropospheric winds 6geo-strophic

winds blowfrom westto east atthe $eryhigh speed

li3ossby wa$es

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• <esterlies at

poles – tomaintain theangularmomentum- they

meander /H3ossby wa$es

• 3ossby wa$es donot meander

consistently" butfollow a cycle /Index cycle

y

Vet streams

8/17/2019 geogra l5 2


•

In westerlies"there are strong"narrow bands ofhigh speed wind

/H Vet stream• Speed of Vet

stream00>mph

V

Vet streams location

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• There are

situated at themargins ofmeridional cells

•

F permanent Vet streams4 29olar Vet and 2Sub-Tropical

<esterly VetST<V

V

2emporar# 1et Vet streams

8/17/2019 geogra l5 2


'ermanent 1et stream

2emporar# 1etstream

• Vet stream Vet streams

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Vet streamembedded in

westerlies3ossby wa$es8at highlatitude" causepressure$ariability

• ThatGs why

they are calledtra$ellingdepression

Vet Stream – tra$elling depressions

8/17/2019 geogra l5 2


<eather of )id and high latitude

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• <eather of higher latitude is more complexthan weather of euatorial or tropical regions

• ecause tropical and euatorial region areheat surplus region– thermal reasons play

the dominant role@• ut higher latitude are heat de(cit region –

dynamic reasons play dominant role

•

These include – localised ; upper-tropospheric circulations 3ossby wa$es" Vetstreams" temperate cyclones8

• 1arge extensi$e body.ir mass

8/17/2019 geogra l5 2


• 1arge extensi$e bodyof air-mass

A000s>m8• ,eight upto

Tropopause

• .t particular height"

one air mass will ha$euniform temperatureand moisture across itswidth

• .irmasses can bedi=erentiate accordingto their temperatureand moisture content

• .ir mass acuired.ir mass

8/17/2019 geogra l5 2


• .ir mass acuiredproperties fromthe source regions– land" marine"polar" arctic"

.ntarctic / gi$ethem identity@ :x@m9" cT

• :xtensi$e

homogeneoussurface ; longerstay ,98

.ir masses

8/17/2019 geogra l5 2


•.ir masses do notstay at theirsource regionsfore$er" they

mo$e out@ <hilemo$ing they cameacross other airmasses@

*ront

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• The relati$edi=erence betweentemperature andmoisture decide

their interactionwith one another

• The border6

meeting region ofthe two air-mass/H *ront

• If cold air mass!old front

8/17/2019 geogra l5 2


If cold air massmo$e faster than

the other than it willlift the warmer oneupward /H coldfront

• the slope will besteep / there willbe sudden up-liftment of the warm

air / cumulonimbusclouds /frontalrainfall

• If warmer air<arm front

8/17/2019 geogra l5 2


• If warmer airmass is moreacti$e than coldfront /H warmfront

•

slope will begentler / therewonGt be suddenup-liftment of

warm air /uniformprolonged rain –dri''le

*ronts

8/17/2019 geogra l5 2


*rontal cyclone

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• .lso called asextra-tropicalcyclone"tra$elling

depressions"cold-corecyclone"wa$e

cyclones

)eaning of cyclone

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A8 Intense 19 system

28 .ir con$erges towards thecentre

8 !losed isobarsF8 In #orthern hemisphere

con$ergence – anti-cloc>wise

Isobar

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(ormal isobar

Closed isobar

!onditions for 19

8/17/2019 geogra l5 2


2hermall# induced

•

ecause of hightemperature

• :x@ 19 at euator

• !on$ectional rainfall

at euator

• pliftment of warm air

• :x@ 19 at sub-polar 19belt

• *rontal rainfall

D#namicall# induced

• )o$ement of+e$elopment of *rontal cyclone

8/17/2019 geogra l5 2


• )o$ement of

airmasses fromtheir source region

• The warm andcold air mass face

each other• . front is created

between them

•

!alled Stationaryfront

*ormati$e stage of frontal cyclone

8/17/2019 geogra l5 2


3ocation of air

masses

Circular movement

• !old air mass+e$elopment of *rontal cyclone

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!old air mass

pushed the warmair mass

• *orced upliftmentof warm air mass

at the cold front/19

• Two cold air masscon$ergence –circular due tocoriolis force

)ature stage

8/17/2019 geogra l5 2


Interaction of air

masses

3' . closed isobars

• &ne cold air mass&ccluded front

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&ne cold air massclimb o$er othercold air mass–warmfront is destroyed

• !alled occluded

front• 3apid change in

temperature andpressure

• nstable weatherconditions

• *rontolysis –t

+issipation of frontal cyclone

8/17/2019 geogra l5 2


no great

temperaturedi=erencebetween twocold air

masses –frontdissipated –19 reduced –cyclonedissipated

Stationaryfront

+ront

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&ccludedfront

+rontol#sis

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9ath of the temperate cyclone

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• .lways west toeast direction

• ecause inuence

of the wetserlies• %radual

mo$ement-9redictable

weather

+istribution of temperate cyclones

8/17/2019 geogra l5 2


,urricane –#@ Tropical cyclone

8/17/2019 geogra l5 2


,urricane #@.merica

Typhoon - !hina

• 1ate summer

• Increased sea

surfacetemperature / 19

• !on$ergence of airaround 19 'one

• 3ising moist wet8air /H absoluteinstability

Tropical cyclone

8/17/2019 geogra l5 2


•!loud formation/more and moremoisture – latentheat of e$aporation

/H cumulo nimbuscloud /H cyclone

• !oriolis forceinduce spiralmo$ement of air

• Intensi(cation of

)ature Tropical cyclone

8/17/2019 geogra l5 2


Intensi(cation of

19• !on$erging air

near watersurface

• !irculating airrises abo$ecoriolis force8

•

+i$erging air atthe top ofcyclone

• .t the centre of the

:ye of the tropical cyclone

8/17/2019 geogra l5 2


• .t the centre of the

cyclone – QeyeG of thetropical cyclone@

• It is a pressuredefect@ ecause" atQeyeG a narrow

stream of winddescend / is ,9 atQeyeG

• .t the eye" there is

clear s>y@• eyond eye wall –

extreme low pressure

9roperties of tropical cyclones

8/17/2019 geogra l5 2


• )o$e swiftly

• It is fuelled bymoisture – sowhen cyclone is

cut-o= from seaand mo$etowards land – itstarts

wea>ening

+istribution of tropical cyclone

8/17/2019 geogra l5 2


2 i l l

comparison

8/17/2019 geogra l5 2


2emperate c#clone

• 0-F0 degree latitude

• +ynamically induced

•

+ue to frontalinteraction

• *ormed o$er largearea

•

)o$e west to east• %radual mo$ement –

predictable

• D-20 degree latitude

• Thermally induced

• +ue to increasing SST

• Small area

• )o$e east to west

•

Swift mo$ement-diWcult to predict path

2ropical c#clone

2 i l l

comparison

8/17/2019 geogra l5 2


2emperate c#clone

• <ind speed F0-50>mph

• 9ressure gradient JD0mb

• 9owerful on land

• .=ect mainland

• )ore time to dissipate

• <ind speed HA20>mph

• 9ressure gradientMDD0 mb

• <ea>ens on land

• .=ect only coastalareas

• ?uic>ly dissipate aftercoming on land

2ropical c#clone

?@ Tropical cyclones arelargely con(ned to

?uestion

8/17/2019 geogra l5 2


)ains

20AF

g y

South !hina Sea" ay ofengal and %ulf of)exico@ <hyB A08

9S!

A8 Tropical

3eason for location of Tropical

cyclone

8/17/2019 geogra l5 2


water

28 <arm oceancurrents

8 Increase SSTin late

summer

F8 Tropicalcyclonemo$e east towest

58 1andmass onwesterncoast

8/17/2019 geogra l5 2


geogra l5 2

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