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Introduction to Meteorology & Climate
Climate, Climate ChangeNuclear Power and the
Alternatives
Introduction to Meteorology & Climate
PHYC 40050
Peter Lynch
Meteorology & Climate Centre
School of Mathematical Sciences
University College Dublin
Climate, Climate ChangeNuclear Power and the
Alternatives
Introduction to Meteorology & Climate
The Composition and StructureThe Composition and Structure
of the Atmosphereof the Atmosphere
Lecture 1Lecture 1
Introduction to Meteorology & Climate
OUR HOME
Introduction to Meteorology & Climate Introduction to Meteorology & Climate
COMPARISON OF HEMISPHERESCOMPARISON OF HEMISPHERES
70% of the globe covered by water70% of the globe covered by water
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Atmospheric CompositionAtmospheric Composition
Introduction to Meteorology & Climate
N2O2
Ar
O3
Inert gasesCO2
H2
SO2,NO2,
CFCs, etc
PMCOCH4
N2O
COMPOSITION OF THE EARTHS ATMOSPHERE
100%100%
1%1%
0.04%0.04%
0.0002%0.0002%
Introduction to Meteorology & Climate
~78%~21%
~1%
.04%
Introduction to Meteorology & Climate
ATMOSPHERIC COMPOSITIONATMOSPHERIC COMPOSITION
MolecularMolecular oxygenoxygen andand nitrogennitrogen are majorare majorcomponentscomponents 99%99%
Of the remaining 1% , 96% is the inertOf the remaining 1% , 96% is the inertgas argongas argon
Of the remaining 4%, 93% is carbonOf the remaining 4%, 93% is carbondioxidedioxide
All remaining gasesAll remaining gases about 2 parts inabout 2 parts in100,000 are known as100,000 are known as trace speciestrace species
These gases control the chemistry of theThese gases control the chemistry of thetropospheretroposphere
Introduction to Meteorology & Climate
THE EARLY ATMOSPHERE
4.6 billion years ago: Earths gravity too weak to hold hydrogenEarths gravity too weak to hold hydrogen
and helium (unlike Sun, Jupiter, Saturn,and helium (unlike Sun, Jupiter, Saturn,Uranus)Uranus)
Earths present atmosphere fromEarths present atmosphere fromvolcanoes (volcanoes (outgassingoutgassing))
Water vapor condensed to form oceansWater vapor condensed to form oceans
COCO22 went into oceans and rockswent into oceans and rocks
NN22
Oxygen forms by breakOxygen forms by break--up of water byup of water bysunlight, later from plants sunlight, later from plants photosynthesisphotosynthesis..
Introduction to Meteorology & Climate
ATMOSPHERIC EVOLUTIONATMOSPHERIC EVOLUTION
EarthsEarths early atmosphereearly atmosphere consisted ofconsisted ofHydrogen (H), Helium (He), MethaneHydrogen (H), Helium (He), Methane
(CH(CH44) and Ammonia (NH) and Ammonia (NH33))
As the earth cooledAs the earth cooled volcanic eruptionsvolcanic eruptions
occurred emitting wateroccurred emitting water vapourvapour (H(H22O),O),carbon dioxide (COcarbon dioxide (CO22) and nitrogen (N) and nitrogen (N22).).
The molecular oxygen (OThe molecular oxygen (O22) in the) in the
current atmosphere came about ascurrent atmosphere came about as
single celled algaesingle celled algae developed in thedeveloped in the
oceans about 3 billion years ago.oceans about 3 billion years ago.
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Oxygen is produced as a byOxygen is produced as a by--product ofproduct ofphotosynthesisphotosynthesis, the making of sugars from, the making of sugars fromwater vapor and carbon dioxide.water vapor and carbon dioxide.
This oxygen producesThis oxygen produces ozoneozone (O(O33) in the) in theupper atmosphere which filtered outupper atmosphere which filtered outharmful ultraviolet radiation from the sun.harmful ultraviolet radiation from the sun.
This allowedThis allowed plantsplants andand animalsanimals totodevelop on land.develop on land.
ATMOSPHERIC EVOLUTIONATMOSPHERIC EVOLUTION
Introduction to Meteorology & Climate
Introduction to Meteorology & Climate
Keeling Curve (Charles Keeling)
Introduction to Meteorology & Climate
CARBON DIOXIDE CYCLECARBON DIOXIDE CYCLE
SourcesSources Plant/animal respirationPlant/animal respiration
Plant decayPlant decay
VolcanoesVolcanoes
Burning of fossil fuelsBurning of fossil fuels
DeforestationDeforestation
SinksSinks Plant photosynthesisPlant photosynthesis
OceansOceans
CarbonatesCarbonates
Introduction to Meteorology & Climate
HYDROLOGICAL CYCLEHYDROLOGICAL CYCLE
Introduction to Meteorology & Climate
HYDROLOGICAL CYCLECYCLE Water is everywhere on earthWater is everywhere on earth
It is in the oceans, glaciers, rivers, lakes, theIt is in the oceans, glaciers, rivers, lakes, theatmosphere, soil, and in living tissueatmosphere, soil, and in living tissue
All these reservoirs constitute theAll these reservoirs constitute the hydrospherehydrosphere
The continuous exchange of water between theThe continuous exchange of water between thereservoirs is called thereservoirs is called the hydrological cyclehydrological cycle
The hydrological cycle is powered by the SunThe hydrological cycle is powered by the Sun
It comprisesIt comprises Evaporation and transpirationEvaporation and transpiration
PrecipitationPrecipitation
Percolation into groundPercolation into ground
RunRun--off to the seaoff to the sea
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Trace Constituents
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Methane and world population
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CFCs: global productionIntroduction to Meteorology & Climate
CFCs: global concentration
Introduction to Meteorology & Climate
Aerosols: particle sizes
1 nm 1 mm1 um|
Introduction to Meteorology & Climate
AEROSOLS Particles suspended in the atmosphereParticles suspended in the atmosphere
Diameters of micronsDiameters of microns one millionth of a meter.one millionth of a meter.
Modify the amount of solar energy reachingModify the amount of solar energy reaching
the surface.the surface.
Act asAct as condensation nucleicondensation nuclei for cloud droplets.for cloud droplets.
PRIMARY SOURCES:PRIMARY SOURCES: Sea salt spraySea salt spray
Wind erosionWind erosion
VolcanoesVolcanoes
FiresFires
Human activityHuman activity
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Introduction to Meteorology & ClimateLos Alamos Fire, 2000
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PRESSURE AND DENSITYPRESSURE AND DENSITY
PressurePressure is the force exerted on a given area.is the force exerted on a given area. Air pressure results when air moleculesAir pressure results when air molecules
move and collide with objects.move and collide with objects.
Air pressure is exerted in all directions.Air pressure is exerted in all directions.
DensityDensity is the concentration of molecules, oris the concentration of molecules, ormass per unit volume.mass per unit volume.
The pressure, density, and temperature of aThe pressure, density, and temperature of agas are all related to each other.gas are all related to each other.
Introduction to Meteorology & Climate Introduction to Meteorology & Climate
PRESSURE AND ALTITUDEPRESSURE AND ALTITUDE
Pressure is measured in terms of inches ofPressure is measured in terms of inches ofmercury, or inmercury, or in millibarsmillibars oror hectopascalshectopascals..
Average seaAverage sea--level pressure is 29.92 incheslevel pressure is 29.92 inchesof mercury or 1013.25of mercury or 1013.25 millibarsmillibars ((hPahPa).).
Atmospheric pressure always decreasesAtmospheric pressure always decreaseswith increasing altitude.with increasing altitude.
The air pressure measured on top of theThe air pressure measured on top of theSugar Loaf is always less than the pressureSugar Loaf is always less than the pressure
inin KilmacanogueKilmacanogue.. To subtract the effect of station elevation,To subtract the effect of station elevation,
air pressure is corrected to report what itair pressure is corrected to report what itwould be at sea level (would be at sea level (sea level pressuresea level pressure))
Introduction to Meteorology & Climate
Density decreases exponentially with heightDensity decreases exponentially with heightIntroduction to Meteorology & Climate
BlaiseBlaise
PascalPascal
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ATMOSPHERIC PRESSUREATMOSPHERIC PRESSURE
Pressure at a point isPressure at a point is the weight of air abovethe weight of air abovethat point.that point.
A column of air of crossA column of air of cross--section 1 squaresection 1 squaremetremetre weighs about 10weighs about 10 tonnestonnes !!
In still air, two factors determine the pressureIn still air, two factors determine the pressure temperature and densitytemperature and density
Ideal gas law:Ideal gas law:
Pressure = ConstantPressure = ConstantXXDensityDensityXXTemperatureTemperature
Pressure decreases with altitude.Pressure decreases with altitude.
Introduction to Meteorology & Climate
ATMOSPHERIC DENSITYATMOSPHERIC DENSITY
The concentration of molecules in measuredThe concentration of molecules in measuredin terms ofin terms ofdensitydensity, or mass per unit volume., or mass per unit volume.
Density at sea level for temperature of 15Density at sea level for temperature of 15CCis about 1.2 kilograms per cubicis about 1.2 kilograms per cubic metremetre..
Density decreases with altitude.Density decreases with altitude.
Introduction to Meteorology & Climate
IDEAL GAS LAWIDEAL GAS LAW The relationship between pressure,The relationship between pressure,
temperature, and volume is given by thetemperature, and volume is given by theideal gas law:ideal gas law:
p = Rp = R TT
where p = pressurewhere p = pressure
R = the gas constantR = the gas constant = (Greek letter= (Greek letter rhorho) density) density
T = temperatureT = temperature
Introduction to Meteorology & Climate
IDEAL GAS LAWIDEAL GAS LAW
Knowing the Ideal Gas Law, you should beKnowing the Ideal Gas Law, you should be
able to say what happens to one variableable to say what happens to one variable
if a change in one of the others occursif a change in one of the others occurs
(while the third remains constant).(while the third remains constant).
E.g., what happens to pressure if densityE.g., what happens to pressure if densityincreases (temperature constant)?increases (temperature constant)?
Introduction to Meteorology & Climate
STRATIFICATION OF THESTRATIFICATION OF THE
ATMOSPHEREATMOSPHERE
Introduction to Meteorology & Climate
The atmosphere can be divided upThe atmosphere can be divided up
according toaccording to pressurepressure (500(500 mbmb layer islayer is
about halfway up in the atmosphere).about halfway up in the atmosphere).
The atmosphere can also be divided upThe atmosphere can also be divided up
according toaccording to temperaturetemperature (which does not(which does not
follow a simple relationship with height).follow a simple relationship with height).
Averaging out temperature values in theAveraging out temperature values in the
atmosphere, we identifyatmosphere, we identify four layersfour layers..
ATMOSPHERIC LAYERSATMOSPHERIC LAYERS
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ATMOSPHERIC LAYERSATMOSPHERIC LAYERS
TroposphereTropospheretemperature decreases with heighttemperature decreases with height
StratosphereStratosphere
temperature increases with heighttemperature increases with height
MesosphereMesosphere
temperature decreases with heighttemperature decreases with height
ThermosphereThermosphere
temperature increases with heighttemperature increases with height
Introduction to Meteorology & Climate
Introduction to Meteorology & Climate
TROPOSPHERETROPOSPHERE
From the surface up to about 12kmFrom the surface up to about 12km(varies with latitude and season(varies with latitude and season higherhigherin Summer, and in the tropics).in Summer, and in the tropics).
Temperature decreases with heightTemperature decreases with heightbecause the troposphere is heated by thebecause the troposphere is heated by thesurface and not directly by sunlight.surface and not directly by sunlight.
Almost all of what we call weatherAlmost all of what we call weatheroccurs in the troposphere.occurs in the troposphere.
Contains 80% of the atmospheres massContains 80% of the atmospheres mass
Introduction to Meteorology & Climate
STRATOSPHERESTRATOSPHERE
Between about 12km and 50km.Between about 12km and 50km.
Temperature increases with height becauseTemperature increases with height becausethethe ozone layerozone layer absorbs ultraviolet light andabsorbs ultraviolet light andwarms up as a result.warms up as a result.
Lack of mixing and turbulence.Lack of mixing and turbulence.
Very little exchange occurs between theVery little exchange occurs between the
stratosphere and troposphere (but it isstratosphere and troposphere (but it isimportant where it does).important where it does).
99.9% of the atmospheric mass below the99.9% of the atmospheric mass below thestratopausestratopause..
Introduction to Meteorology & Climate
MESOSPHERE & THERMOSPHEREMESOSPHERE & THERMOSPHERE
Mesosphere between 50km and 85km.Mesosphere between 50km and 85km.
Thermosphere goes up and up and up: thereThermosphere goes up and up and up: thereis no clear separation between theis no clear separation between thethermosphere and interplanetary space.thermosphere and interplanetary space.
The highest temperatures in the atmosphereThe highest temperatures in the atmosphereare found in the thermosphere due to highare found in the thermosphere due to highenergy radiation being absorbed by gases.energy radiation being absorbed by gases.
Ionosphere (charged gas atoms) thatIonosphere (charged gas atoms) thatreflects radio waves, and aurora are here.reflects radio waves, and aurora are here.
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1. Troposphere- literally means region where air turns over
-temperature usually decreases (on average ~6.5C/km) with altitude
2. Stratosphere- layer above the tropopause, little mixing occurs inthe stratosphere, unlike the troposphere, where turbulent mixing
is common
3. Mesosphere- defined as the region where temperature again
decreases with height.
4. Thermosphere- region with very little of the atmospheres mass.
High energy radiation received by the thermosphere: high
temperatures. Very low density (not much heat felt).
Tropopause
Stratopause
Mesopause
Introduction to Meteorology & Climate
Introduction to Meteorology & Climate
In meteorology we often refer to altitudeas a certain pressure value rather than height.
The atmosphere moves mainly on constantpressure surfaces (isobaric surfaces)
850 mb 1500 m (5000 ft)
700 mb 3000 m (10,000 ft)
500 mb 5500 m (18000)
300 mb 9000 m (30,000)
Introduction to Meteorology & Climate
Introduction to Weather MapsIntroduction to Weather Maps
Introduction to Meteorology & Climate
ATMOSPHERIC FRONTSATMOSPHERIC FRONTS FrontFront a boundary between two regions ofa boundary between two regions of
air that have different meteorologicalair that have different meteorologicalproperties, e.g. temperature or humidity.properties, e.g. temperature or humidity.
Cold frontCold front a region where cold air isa region where cold air isreplacing warmer air.replacing warmer air.
Warm frontWarm front a region where warm air isa region where warm air isreplacing colder air.replacing colder air.
Stationary frontStationary front a front that is not moving.a front that is not moving.
Occluded frontOccluded front a front where warm air isa front where warm air isforced aloft.forced aloft.
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WARM FRONT
Introduction to Meteorology & Climate
COLD FRONT
Introduction to Meteorology & Climate
SYNOPTIC
WEATHER CHARTIntroduction to Meteorology & Climate
WEATHER PLOTTING SYMBOLSWEATHER PLOTTING SYMBOLS
Introduction to Meteorology & Climate Introduction to Meteorology & Climate
METEOROLOGICAL TIMEMETEOROLOGICAL TIME
All weather reports areAll weather reports are labelledlabelled usingusingCoordinated Universal Time (UTC),Coordinated Universal Time (UTC),also called Greenwich Mean Timealso called Greenwich Mean Time(GMT), and also denoted Zulu (Z).(GMT), and also denoted Zulu (Z).
Zulu is the time along the 0Zulu is the time along the 0 longitudelongitudeline, which runs through Greenwich.line, which runs through Greenwich.
Meteorology uses the 24 hour clockMeteorology uses the 24 hour clockwhich omits the use of a.m. and p.m.which omits the use of a.m. and p.m.(0900 = 9 a.m., 2100 = 9 p.m.)(0900 = 9 a.m., 2100 = 9 p.m.)
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Revision: Layers of the AtmosphereRevision: Layers of the Atmosphere
Hot top: oxygenHot top: oxygenabsorbs sunlightabsorbs sunlight
Warm middle: ozoneWarm middle: ozoneabsorbs ultraviolet (UV)absorbs ultraviolet (UV)
Warm surface: land andWarm surface: land andocean absorb sunlightocean absorb sunlight
Introduction to Meteorology & Climate
End of Lecture 1End of Lecture 1