A processprocess whenwhen waterwater getsgets intointo thethe atmosphereatmosphere fromfrom purepure soilsoil surfacesurface and/and/oror waterwater surfacesurface ((evaporation)

TEMPORAL AND SPATIAL CHANGES TEMPORAL AND SPATIAL CHANGES

OF CLIMATE ELEMENTS IN OF CLIMATE ELEMENTS IN

HUNGARY HUNGARY

EVAPOTRANSPIRATION, EVAPOTRANSPIRATION,

AIR HUMIDITY, FOG, AIR HUMIDITY, FOG,

CLOUDINESS

CLOUDINESS

EVAPOTRANSPIRATION EVAPOTRANSPIRATION

Evapotranspiration

Evapotranspiration is a changeis a change of phaseof phase, , forfor whichwhich energyenergy is providedis provided byby solarsolar radiationradiation absorbedabsorbed byby thethe surface.surface.

InIn meteorologicalmeteorological sensesense evapotranspirationevapotranspiration is is thethe processprocess, , whenwhen water

water fromfrom largelarge--scalescale naturalnatural oror atificialatificial surfacesurface getsgets intointo thethe atmosphere

atmosphere. .

Evapotranspiration

Evapotranspiration has twohas two components:components: 1. A

1. A processprocess whenwhen waterwater getsgets intointo thethe atmosphereatmosphere fromfrom purepure soilsoil surfacesurface and/and/oror waterwater surfacesurface ((evaporation). evaporation).

2. A

2. A processprocess whenwhen waterwater getsgets intointo thethe atmosphereatmosphere throughthrough plantplant metabolism

metabolism (transpiration(transpiration).).

Water

Water amountamount gotgot intointo thethe atmosphereatmosphere fromfrom a unit surfacea unit surface and unit and unit timetime (mm/year(mm/year).).

Water

Water cencen getget toto thethe atmosphereatmosphere throughthrough twotwo processes:processes:

1.1. InIn casecase of givenof given climaticclimatic conditionsconditions a givena given waterwater amountamount thatthat maymay be potentiallybe potentially vaporized: vaporized: potentialpotential evapotranspirationevapotranspiration (PET)

(PET)..

2.2. A givenA given waterwater amountamount thatthat is actuallyis actually vaporizedvaporized duringduring a unit a unit timetime actualactual evapotranspirationevapotranspiration (AET)(AET). In. In everyevery casecase

AETAET ≤≤ PET.PET.

Annual

Annual coursecourse of AET followsof AET follows thethe annualannual coursecourse of temperatureof temperature: : minimum

minimum inin JanuaryJanuary, maximum in, maximum in July.July.

ItsIts geographicalgeographical distributiondistribution followsfollows thatthat of radiationof radiation budgetbudget and and temperature

temperature: Alf: Alföld: 800öld: 800--850 mm; a 850 mm; a narrownarrow beltbelt alongalong thethe DráDráva va River

River: 900 mm; a : 900 mm; a substantialsubstantial part of Dunpart of Dunáántúntúl: 700l: 700--750 mm; 750 mm;

mountainous

mountainous regionsregions: around: around 600 mm.600 mm.

Air Air humidity humidity characteristics characteristics determining determining evaporation evaporation

absolute

absolute humidityhumidity (s):(s): massmass of waterof water vapourvapour inin a unit volumea unit volume of moistof moist air (= densityair (= density of waterof water vapour): (gvapour): (g⋅m⋅m^--33););

specific

specific humidityhumidity (q):(q): massmass of waterof water vapourvapour inin a unit massa unit mass of of moist

moist air (air (––); );

vapour

vapour pressurepressure (e):(e): partialpartial pressurepressure of waterof water vapourvapour inin thethe air (

air (mbmb););

saturated

saturated vapourvapour pressurepressure (E):(E): atat a givena given temperature, temperature, thethe partial

partial pressurepressure of theof the maximum admissablemaximum admissable waterwater vapourvapour inin thethe air (

air (mbmb););

saturation

saturation deficitdeficit (d):(d): itit showsshows thethe differencedifference betweenbetween thethe saturated

saturated vapourvapour pressurepressure atat a givena given temperaturetemperature and theand the actually

actually observedobserved vapourvapour pressurepressure atat thethe samesame temperaturetemperature: : d=Ed=E−e −e ((mbmb););

relatrelativeive hunmidityhunmidity (RH):(RH): itit expressesexpresses thethe actualactual vapourvapour pressure

pressure inin percentagepercentage of theof the saturationsaturation vapourvapour pressurepressure belonging

belonging toto thethe observedobserved temperature: RHtemperature: RH=e/=e/((E*100E*100)) (%(%););

dewdew pointpoint (t(t_dd):): thisthis is theis the temepraturetemeprature toto whichwhich thethe unsaturated

unsaturated air, comprisingair, comprising water, water, shouldshould be cooledbe cooled onon constantconstant pressure

pressure forfor reachingreaching saturationsaturation (°(°CC););

dewdew pointpoint depressiondepression ((∆)∆):: thisthis is theis the differencedifference betweenbetween thethe actual

actual temperaturetemperature and theand the dewdew point: point: ∆∆ = t –= t – tt_dd ((°C°C););

Ways Ways of of calculations calculations

Computation

Computation I. I.

- - heat heat budget budget method method

- - aerodynamic aerodynamic method method – – Dalton formula: Dalton formula:

( )

arány Bowen

ahol L

Q P R

: 1 β

β +

= −

( ^{E e szél} )

f

P = − ;

Computation

Computation II. II.

- - water water balance balance method method

P= W P= W

+ Csap. + Csap. - - W W

- - empirical empirical procedures procedures

measurement

measurement – – by by evaporation

evaporation bath bath

( ( principle principle ) )

Mean monthly and annual sums of potential evapotranspiration, mm, 1901-1950

Station year

Areal distribution of the annual sums of potential evapotranspiration in Hungary

The temporalThe temporal coursecourse of AET is alsoof AET is also similar: maximum similar: maximum is is inin July, July, minimum

minimum is is inin JanuaryJanuary..

ItsIts meanmean valuevalue isis 450-450-550 mm in550 mm in Hungary.Hungary.

ItsIts regionalregional distributiondistribution is significantlyis significantly differentdifferent fromfrom PET, PET, sincesince itsits amount

amount is determinedis determined byby thethe precipitationprecipitation and and thethe resourcesresources of theof the soilsoil forfor a givena given areaarea..

ItsIts minimum is minimum is inin AlföAlföld, ld, whilewhile itsits maximum is maximum is inin WestWest-Dun-Dunáántntúúl l and and thethe mountainous

mountainous regions.regions. Regarding

Regarding relativerelative changeschanges of PET of PET andand AET, AET, theirtheir valuevalue is theis the samesame

fromfrom OctoberOctober toto May, dueMay, due toto thethe substantialsubstantial moisturemoisture supplysupply of of thethe soil. soil. However

However, , betweenbetween JuneJune and Septemberand September, because, because of theof the desiccaroiondesiccaroion ofof thethe soil, AET soil, AET legslegs behindbehind thethe PET valuesPET values..

Maximum

Maximum valuesvalues ofof AET AET differdiffer inin variousvarious regionsregions of Hungary, of Hungary, sincesince thethe dates

dates of highof high temperaturetemperature and highand high precipitationsprecipitations dodo notnot coincidecoincide either

either. .

Mean monthly and annual sums of the actual evapotranspiration, mm, 1901-1950

Mean annual sums of the actual evapotranspiration, mm, Hungary

Climatic water budget = annual sum of precipitation – annual sum of PET

Mean annual value of the climatic water budget, mm, Hungary

Relationship

Relationship of PET and AET during of PET and AET during the the year year

Water shortage

month

Zonal averages of the annual actual evapotranspiration (AET) over land surfaces, as well as those of the annual potential evaporation (ET_pot)

over oceanic surfaces (Potential evaporation over oceanic surfaces equals to the potential evapotranspiration) (after Budiko, 1956)

Geographical coordinates land surfaces

oceans

Annualevaporation, mm

AIR HUMIDITY AIR HUMIDITY

Air Air humidity humidity is is the the water water vapour vapour content content of of the the air. air. It It has two has two sources sources : :

1. 1. Evaporation Evaporation and and transpiration transpiration from from the the components

components of of clouds clouds and and precipitations precipitations , , as as well well as as from from the the surface surface

2. 2. Water Water vapour vapour advection advection from from distant distant lands. lands . Air masses of marine origin coming from

the direction of the Icelandic minimum (+), as well as the continental air masses (-)

caused water vapour advection . . Among

Among the the several several parameters parameters water water vapour vapour and and relative

relative humidity humidity are are used used to to characterize characterize air air humidity

humidity in in climatology. climatology .

Monthly and annual averages of water vapour (hPa) and relative humidity (%), 1901-1950

Relative humidity Water vapour

year year

station station

Annual course of relative humidity (%) and water vapour (mm) based on the 80-year averages of the daily mean values,

Budapest, 1871-1959 (after Kakas)

Annual

Annual coursecourse of waterof water vapourvapour is cahracterizedis cahracterized byby JulyJuly maximum maximum and Januaryand January minimum, sinceminimum, since thethe increaseincrease of temperatureof temperature enhancesenhances surface

surface evapotranspirationevapotranspiration..

The summerThe summer vapourvapour pressurepressure maximum substantiallymaximum substantially contributescontributes toto the development of summer precipitation maximum.the .

Contrary

Contrary toto this, this, relativerelative humidityhumidity reacgesreacges itsits maximum inmaximum in December

December--JanuaryJanuary, and its, and its minimum inminimum in July.July.

ThisThis is becauseis because withwith thethe increaseincrease of air temperatureof air temperature, , thethe saturationsaturation vapour

vapour pressurepressure alsoalso increases; increases; thereforetherefore, , smallersmaller waterwater vapourvapour amount

amount atat lowerlower temperaturetemperature cancan induceinduce greatergreater relativerelative saturation.saturation. Monthly

Monthly and and annualannual averagesaverages of waterof water vapourvapour show rathershow rather uniform uniform picture

picture forfor thethe wholewhole areaarea of Hungary, thisof Hungary, this is whyis why itit isis notnot worthworth toto display

display thisthis map.map.

Spatial

Spatial distributiondistribution of relativeof relative humidityhumidity showsshows a mucha much more more interpretable

interpretable regionalregional picture.picture. During

During thethe winterwinter monthsmonths relativerelative humidityhumidity is uniformlyis uniformly highhigh acrossacross thethe country, withcountry, with valuesvalues aroundaround 75%.75%.

During

During thethe summersummer monthsmonths, , duedue toto thethe invasioninvasion of oceanicof oceanic and and continental

continental air air massesmasses of differentof different humidity, humidity, thethe regionalregional distributiondistribution ofof relativerelative humidityhumidity is muchis much more more varied.varied.

InIn DunáDunántntúúl l areaarea, , fromfrom westwest toto easteast, parallel , parallel toto thethe weakeningweakening of of thethe oceanicoceanic effecteffect decreasingdecreasing valuesvalues stand out (75-stand out (75-60%)60%)

InIn AlföAlföld ld areaarea, a concentric, a concentric distributiondistribution duedue toto thethe basinbasin charactercharacter withwith valuesvalues of 55-of 55-70% 70% occur.occur.

WhenWhen MediterraneanMediterranean air massesair masses comecome fromfrom south-south-easteast, 10-, 10-15% 15%

relative

relative humidityhumidity maymay happenhappen inin thethe south-south-easteast part of Alföpart of Alföld inld in summer

summer..

Geographical distribution of mean relative humidity (%), July, Hungary

Relative humidity in the middle months of the seasons, (%)

January April

July October

FOG FOG

WhenWhen precipitatedprecipitated withinwithin volume, volume, suddenlysuddenly a largea large numbernumber of tinyof tiny water

water dropletsdroplets and/and/oror iceice crystalscrystals areare formedformed whichwhich willwill obscureobscure thethe clear

clear air.air.

ThenThen fog fog oror cloudcloud is generatedis generated, , dependingdepending onon whetherwhether thethe processprocess develops

develops onon thethe groundground oror inin highhigh altitudealtitude air.air.

Thus, Thus, therethere is no physicalis no physical differencedifference betweenbetween thethe twotwo phenomena: phenomena: cloud

cloud oror fog arefog are referredreferred toto asas a coherenta coherent part of thepart of the atmopshere, atmopshere, inin which

which thethe veryvery smallsmall waterwater dropletsdroplets and/and/oror iceice crystalscrystals areare floatingfloating inin suchsuch a largea large numbernumber thatthat theythey makemake an obstaclean obstacle toto thethe pathpath of of thethe solarsolar radiation.radiation.

Foggy

Foggy dayday is consideredis considered thethe day, day, whenwhen thethe visiibilityvisiibility isis less thanless than 1 1 km duekm due toto thethe formerformer reason, reason, forfor anyany lengthlength of timeof time..

The air

The air coolscools byby contact, contact, whenwhen flowingflowing over a colderover a colder surfacesurface ((frozenfrozen soil, soil, snowsnow cover). cover). ThisThis processprocess resultsresults inin flowingflowing fog. Itfog. It is alsois also calledcalled advective

advective, , oror frontalfrontal fog,fog, because_because suchsuch situationsituation developsdevelops inin thethe casecase of frontof front-associated-associated moisturemoisture advection. advection.

AsAs a resulta result of surfaceof surface radiation, radiation, thethe air cooledair cooled atat nightnight aboveabove thethe soilsoil maymay coolcool toto itsits dewdew pointpoint, or, or below, below, onon whichwhich waterwater vapourvapour

becomes

becomes saturated. saturated. InIn thisthis way, way, condensationcondensation generallygenerally takestakes placeplace onlyonly inin a thina thin layerlayer closeclose toto thethe groundground; so; so, , radiationradiation fog is fog is

generated generated..

Condensation

Condensation cancan occuroccur byby mixing somixing so thatthat twotwo air massesair masses of of different

different temperaturetemperature and and closeclose toto saturationsaturation mix togethermix together. The . The resulting

resulting jointjoint temperaturetemperature willwill be lowerbe lower thanthan thethe warmerwarmer air. Thusair. Thus, , itit is saturatedis saturated withwith waterwater vapourvapour, and mixing fog or, and mixing fog or cloudcloud is formedis formed. .

Mean monthly and annual number of foggy days, 1940-1954

station year

Frequency

Frequency of of fogsfogs is associatedis associated withwith thethe annualannual coursecourse of relativeof relative humidity

humidity ofof aroundaround 100%, and varies100%, and varies oppositeopposite toto temperaturetemperature.. The most

The most foggyfoggy periodperiod is December 6is December 6-12 (-12 (inin thethe mountainsmountains December 12

December 12--15) 15) wherewhere daytimedaytime is alsois also foggy. foggy. SecondarySecondary and and tertiary

tertiary maxima aremaxima are autumnautumn and and sprong, sprong, respectivelyrespectively. . SummerSummer is is practically

practically fogfog--free. free.

Daily

Daily coursecourse of fog frequencyof fog frequency is oppositeis opposite toto thatthat of of temperature: temperature: thethe most

most foggyfoggy is dawnis dawn, while, while thethe leastleast foggyfoggy periodperiod isis aroundaround noon.noon. Regarding

Regarding geographicalgeographical distribution, distribution, thethe leastleast foggyfoggy areasareas areare thethe most

most windywindy KisalfKisalföld and öld and thethe regionregion betweenbetween Duna and Tisza Duna and Tisza (20-(20-30 30 foggyfoggy daysdays onon annualannual average).average).

AtAt severalseveral regionsregions inin AlföAlföld and Dunld and Dunáántntúúl l areasareas 40-40-60 60 foggyfoggy daysdays per yearper year areare characteristic.characteristic.

Mountain

Mountain valleysvalleys areare thethe most foggymost foggy areas: areas: withwith 60-60-120 120 foggyfoggy daysdays onon annualannual average.average.

CLOUDINESS CLOUDINESS

Cloudiness

Cloudiness has a has a fundamentalfundamental importanceimportance inin formingforming sunshinesunshine duration

duration.. Under

Under cloudinesscloudiness, we, we understandunderstand coveragecoverage of theof the skysky byby cloudsclouds and/orand/or thickthick fog, fog, expressedexpressed inin percentagepercentage oror octa.octa.

ItsIts valuevalue cancan be estimatedbe estimated, , withoutwithout usingusing instrumenation. Te instrumenation. Te skysky is is divided

divided imaginaryimaginary intointo eighteight equalequal partsparts and itand it is determinedis determined thatthat howhow bigbig part is part is coveredcovered byby clouds.clouds.

The completelyThe completely cloudlesscloudless skysky is indicatedis indicated byby 00 (0%), (0%), thethe completelycompletely covered

covered skysky byby 8 o8 occtata (100%)(100%). At. At nightnight cloudcloud coveragecoverage is assessedis assessed onon howhow manymany eigtheigth of theof the skysky is free of starsis free of stars. .

WhenWhen observingobserving clouds,clouds, theirtheir height, height, type, type, quantityquantity and passand pass shouldshould alsoalso be consideredbe considered..

Monthly and annual averages of cloudiness,

%, 1901-1950

station year

WhenWhen studyingstudying annualannual coursecourse of of cloudinesscloudiness, , thethe most most clearclear skysky is is characteristic

characteristic atat thethe end of end of summersummer ((frequentfrequent anticyclonicanticyclonic largelarge-- scale

scale weatherweather situationssituations),),

DueDue toto frequentfrequent fog fog formation, formation, associatedassociated withwith cycloniccyclonic large-large-scalescale weather

weather situationssituations, , thethe most cloudymost cloudy is December.is December.

Daily

Daily coursecourse of cloudinessof cloudiness is specificis specific. The . The leastleast cloudycloudy is lateis late evening

evening inin everyevery season. season. HoweverHowever, the, the timetime of of greatestgreatest cloudinesscloudiness differs

differs betweenbetween winterwinter and and summer.summer.

InIn thethe summer, summer, duedue toto thethe intensiveintensive cloudcloud ((cumulus) cumulus) formationformation, , early

early afternoonafternoon is theis the most most cloudy.cloudy.

InIn thethe winter, winter, duedue toto thethe frequentfrequent fogfog-- and lowand low stratusstratus formation, formation, asas a resulta result of nocturnalof nocturnal radiation, radiation, dawndawn and and morningmorning areare thethe most most

cloudy cloudy..

Geographical distribution of mean annual cloudiness (%) in Hungary

Based

Based onon thethe annnualannnual averageaverage of cloudof cloud coveragecoverage (%), the(%), the smallestsmallest cloudiness

cloudiness occursoccurs inin thethe middlemiddle part of Alföpart of Alföld ld areaarea (>(>50 %), due50 %), due toto thethe basinbasin character.character.

Towards

Towards thethe edgesedges of theof the basin, basin, cloudinesscloudiness is graduallyis gradually inreasinginreasing except

except forfor thethe southernsouthern foregroundforeground of theof the NorthernNorthern Medium-Medium-highhigh Mountains

Mountains, , wherewhere duedue toto windswinds ofof foehnfoehn charactercharacter lowlow clloudinessclloudiness is is characteristic

characteristic, , similarlysimilarly toto AlföAlföld ld areaarea.. The most

The most cloudycloudy regionregion is is thethe edgeedge areaarea atat West Hungary, West Hungary, wherewhere cloud

cloud coveragecoverage reachesreaches 70%.70%.

ForFor characterizingcharacterizing cloudinesscloudiness, , thethe numbernumber of of clearclear ((cloudcloud covercover <<

20%) and

20%) and cloudycloudy ((cloudcloud covercover >> 80%) 80%) daysdays areare usedused.. The most

The most clearclear regionregion occursoccurs inin thethe middlemiddle of Alföof Alföld ld areaarea (Kecskem

(Kecskeméét: 90 t: 90 daysdays), ), whilewhile thethe most most cloudycloudy is Zempléis Zempléni Mountain ni Mountain and theand the FoothillFoothill of theof the AlpsAlps (Sopron: 40 days(Sopron: 40 days).).

The meanThe mean annualannual numbernumber of of cloudycloudy daysdays varyvary betweenbetween 80 80 (Kecskem

(Kecskeméét) and 140 (Sopron).t) and 140 (Sopron).

Geographical distribution of the mean annual number of

clear days in Hungary

Geographical distribution of the mean annual number of

cloudy days in Hungary

Always look on the bright side of things!

We finished for today, goodbye!

ق ا ا إ اد د

ق ا ا إ اد د

ﻣ ﻣ ! ! ء ء ا ا

让我们总是从光明的一面来看待事 物吧！

今天的课程到此结束，谢谢！

ямарваа нэг зүйлийн гэгээлэг талыг нь үргэлж олж харцгаая

өнөөдөртөө ингээд дуусгацгаая, баяртай

"#$%&#ا

"#$%&#ا اذ%) اذ%)

،مو$)ا

،مو$)ا

"-ادو

"-ادو

! !