The AtmosphereThe Atmosphere

Atmospheric CompositionAtmospheric CompositionComponentComponent % of % of

atm.atm.Information:Information:

Nitrogen Nitrogen (N(N22))

7878 Fundamental Nutrient for living Fundamental Nutrient for living organismsorganisms

Oxygen (OOxygen (O22)) 2121 Enter atm. in photosynthesis; removed in Enter atm. in photosynthesis; removed in cellular respiration. cellular respiration.

Water Vapor Water Vapor (H(H22O)O)

0-40-4 Varies depending on region: more over Varies depending on region: more over oceans and at equator; less over deserts oceans and at equator; less over deserts and near polesand near poles

Carbon Carbon Dioxide Dioxide (CO(CO22))

<<1<<1 Taken up in photosynthesis; release in Taken up in photosynthesis; release in cellular respiration; increased 25% in cellular respiration; increased 25% in past 300 yearspast 300 years

Methane Methane (CH(CH44))

<<<<<<11

Contributes to green house effect; Contributes to green house effect; increased 150% since 1750increased 150% since 1750

Nitrous Nitrous Oxide (NOxide (N22O)O)

<<<<<<11

Comes from burning fossil fuels and Comes from burning fossil fuels and deforestationdeforestation

Ozone (OOzone (O33)) <<<<<<11

97% in stratosphere (ozone layer); 97% in stratosphere (ozone layer); absorbs UV radiationabsorbs UV radiation

Structure of AtmosphereStructure of AtmosphereLayersLayers Height Height

above above Earth’s Earth’s SurfaceSurface

Information:Information:

TroposphereTroposphere 0-11km0-11km 75% of atmospheric mass; 75% of atmospheric mass; Temperature decreases with Temperature decreases with altitude; weather occurs herealtitude; weather occurs here

StratosphereStratosphere 11 – 50 11 – 50 kmkm

Temperature increases with altitude Temperature increases with altitude due to absorption of heat by ozone due to absorption of heat by ozone layer; ozone layer herelayer; ozone layer here

MesosphereMesosphere 50 – 80 50 – 80 kmkm

Temperature decreases with Temperature decreases with altitude; coldest layer; meteors burn altitude; coldest layer; meteors burn up in this layer; ice clouds hereup in this layer; ice clouds here

ThermospherThermosphere e (Ionosphere)(Ionosphere)

80+ km80+ km Temperature increase with altitude Temperature increase with altitude due to gamma and x-rays and UV due to gamma and x-rays and UV radiation; auroa borealis and auroa radiation; auroa borealis and auroa australis hereaustralis here

Structure of AtmosphereStructure of Atmosphere

Weather and ClimateWeather and Climate

WEATHER ≠ WEATHER ≠ CLIMATECLIMATE

WeatherWeather• The short-term conditions of the The short-term conditions of the

atmosphere in a given placeatmosphere in a given place• Influenced by the movement or transfer of Influenced by the movement or transfer of

heat energyheat energy• Influences:Influences:

– TemperatureTemperature– Air pressureAir pressure– HumidityHumidity– PrecipitationPrecipitation– Available sunshine (lack of cloud cover)Available sunshine (lack of cloud cover)– Wind speedWind speed– Wind directionWind direction

She is reporting weatherShe is reporting weather

ClimateClimate

• The total of all weather occurring The total of all weather occurring over a period of years in a given over a period of years in a given placeplace

• Energy transfered through:Energy transfered through:– RadiationRadiation– ConductionConduction– ConvectionConvection

Factors that influence Factors that influence climateclimate• Air MassAir Mass• Air PressureAir Pressure• AlbedoAlbedo• AltitudeAltitude• Angle of sunlightAngle of sunlight• Carbon CycleCarbon Cycle• CloudsClouds• Distance to OceansDistance to Oceans• FrontsFronts• Greenhouse EffectGreenhouse Effect• Heat (convection)Heat (convection)• Land ChangesLand Changes• Land mass distributionLand mass distribution

• LatitudeLatitude• LocationLocation• Moisture content of Moisture content of

the airthe air• Mountain rangesMountain ranges• Plate Tectonics Plate Tectonics • PollutionPollution• PrecessionPrecession• RotationRotation• Solar OutputSolar Output• VolcanoesVolcanoes• Wind PatternsWind Patterns• Human ActivityHuman Activity

Air MassAir Mass

• Large Body of air that has similar Large Body of air that has similar temperature and moisture contenttemperature and moisture content

• Categorized by:Categorized by:– EquatorialEquatorial– TropicalTropical– PolarPolar– ArcticArctic– ContinentalContinental– MaritimeMaritime

Air PressureAir Pressure• Decreases with altitude (99% within Decreases with altitude (99% within

20 mi of earths surface)20 mi of earths surface)

• Low Pressure Masses: produces Low Pressure Masses: produces cloudy and stormy weathercloudy and stormy weather

• High Pressure masses: contain cool High Pressure masses: contain cool dense air; drops to Earth’s surface dense air; drops to Earth’s surface and becomes warmerand becomes warmer– Associated with fair (nice) weatherAssociated with fair (nice) weather

AlbedoAlbedo

• ReflectivityReflectivity– Oceans – lowOceans – low– Land masses – moderateLand masses – moderate– Snow and Ice – highSnow and Ice – high

• Positive feedback mechanismPositive feedback mechanism

• Dust in air can form a high albedo Dust in air can form a high albedo layer in the atmosphere and reflects layer in the atmosphere and reflects sunlight backsunlight back– Temporarily cooling the atmosphereTemporarily cooling the atmosphere

AltitudeAltitude

• Every 1000 feet (300m) rise in Every 1000 feet (300m) rise in elevation = 3elevation = 3°°F drop in temperatureF drop in temperature

• Every 300 feet (90m) rise in Every 300 feet (90m) rise in elevation = 62mi (100 km) shift elevation = 62mi (100 km) shift north in latitude and biome north in latitude and biome similaritiessimilarities

Altitude changesAltitude changes

Angle of sunlightAngle of sunlight• Areas of the earth closest to the sun Areas of the earth closest to the sun

receive more sunlight and have a higher receive more sunlight and have a higher temperaturetemperature

Carbon CycleCarbon Cycle

CloudsClouds• Collections of water droplets or ice crystals Collections of water droplets or ice crystals

suspended in the atmosphere suspended in the atmosphere

Distance to OceansDistance to Oceans

• Oceans are thermally more stable Oceans are thermally more stable than landthan land– Changes in temperature are more Changes in temperature are more

extreme in center of land masses than extreme in center of land masses than near the oceansnear the oceans

FrontsFronts

• Boundary between two air massesBoundary between two air masses• Vary byVary by

– TemperatureTemperature– Dew pointDew point– Wind directionWind direction

• Cold fronts – leading edge of an Cold fronts – leading edge of an advancing cold air massadvancing cold air mass– Associated with thunderstormsAssociated with thunderstorms

Greenhouse effectGreenhouse effect

• Water, carbon dioxide, and methane Water, carbon dioxide, and methane trap solar radiationtrap solar radiation– Too much = Earth too hot to live onToo much = Earth too hot to live on– Too little = Earth too cold to live onToo little = Earth too cold to live on

Heat (Convection)Heat (Convection)

Convection:Convection:

• Primary way energy Primary way energy is transferred from is transferred from hotter to colder hotter to colder regions in the regions in the Earth’s atmosphere Earth’s atmosphere

• Primary determinant Primary determinant of weather patternsof weather patterns

Conduction:Conduction:

• Involves the heat Involves the heat transfer through a transfer through a substance heat substance heat results from results from different different temperatures in temperatures in different parts of different parts of that substancethat substance

Atmospheric Convection Atmospheric Convection CellCell

Land Mass DistributionLand Mass Distribution

• Oceans absorb more solar heat than Oceans absorb more solar heat than land massesland masses

• Earth receives more solar radiation Earth receives more solar radiation at low latitudes (near the equator) at low latitudes (near the equator) than at high latitudesthan at high latitudes

• More landmasses near the equator More landmasses near the equator leads to a cooler planetleads to a cooler planet

Latitude Latitude • High latitude = less solar radiation = cooler High latitude = less solar radiation = cooler

climateclimate

Land ChangesLand Changes

• DeforestationDeforestation

• UrbanizationUrbanization

Moisture Content (Humidity)Moisture Content (Humidity)

• Atmospheric water vapor:Atmospheric water vapor:– Provides moisture for clouds and rainProvides moisture for clouds and rain– Acts as a green house gas keeping the Acts as a green house gas keeping the

Earth warmEarth warm

• A primary determinant of plant A primary determinant of plant growth growth – Determines type of biomeDetermines type of biome

• Dew point – temperature at which Dew point – temperature at which condensation takes placecondensation takes place

Mountain RangesMountain Ranges

• Force air masses from a low elevation to a Force air masses from a low elevation to a high elevationhigh elevation– Air mass expands and cools as it risesAir mass expands and cools as it rises– Relative humidity is raisedRelative humidity is raised– Clouds form (sometimes get rain)Clouds form (sometimes get rain)

• Windward side of the range gets the most Windward side of the range gets the most rainrain

• The leeward side gets the least rain The leeward side gets the least rain creating a rain shadow effect and producing creating a rain shadow effect and producing a different biomea different biome

Rain shadow effectRain shadow effect

Plate Tectonics Plate Tectonics

• Stable plate tectonics leads to less Stable plate tectonics leads to less volcanism volcanism

• Less volcanism means less carbon Less volcanism means less carbon dioxide in the atmosphere dioxide in the atmosphere cooler cooler planetplanet

• More plate movement More plate movement more more volcanism volcanism more greenhouse more greenhouse gasses gasses hotter planet hotter planet

PollutionPollution

• Greenhouse gasses from human Greenhouse gasses from human sources sources increase in global increase in global temperaturetemperature

• CFC’s damage the ozone layerCFC’s damage the ozone layer

• Excess sulfur Excess sulfur acid rain acid rain

PrecessionPrecession

• Precession – the wobble of the Earth Precession – the wobble of the Earth on it’s axison it’s axis

• Changes in precession Changes in precession changes in changes in the amount of sunlight the earth the amount of sunlight the earth receives receives atmospheric changes atmospheric changes

RotationRotation

• Daily temperature changes are affected Daily temperature changes are affected by the Earth’s 24 hour rotation cycle (1 by the Earth’s 24 hour rotation cycle (1 day)day)

• Solar radiation warms the planet during Solar radiation warms the planet during the daythe day

• Heat escapes the planet at night Heat escapes the planet at night

Solar OutputSolar Output

RadiationRadiation

• Flow of electromagnetic radiation from the Flow of electromagnetic radiation from the sunsun

• Adds energy to the Earth’s systemsAdds energy to the Earth’s systems

VolcanoesVolcanoes• Volcano aerosols:Volcano aerosols:

– Sulfur ejected into the stratosphere warms Sulfur ejected into the stratosphere warms the stratosphere and cools the troposphere.the stratosphere and cools the troposphere.

– Can destroy ozoneCan destroy ozone– Carbon dioxide – green house gasCarbon dioxide – green house gas

• Increased iron Increased iron increased biological increased biological activity activity take up carbon dioxide and take up carbon dioxide and cool the atmospherecool the atmosphere

• Large eruptions may trigger El Niño Large eruptions may trigger El Niño eventsevents

Wind PatternsWind Patterns

• Influenced by:Influenced by:– TemperatureTemperature– Pressure differencesPressure differences– Coriolis effectCoriolis effect

Wind PatternsWind Patterns

1.1. Sun heats the atmosphere unevenlySun heats the atmosphere unevenly

2.2. Air closest to the surface warms Air closest to the surface warms and risesand rises

3.3. Air at high elevations cools and Air at high elevations cools and sinkssinks

4.4. Rising and falling sets up a Rising and falling sets up a convection process convection process wind wind

Global Air CirculationGlobal Air Circulation

• Caused and affected by:Caused and affected by:– Uneven heating of the Earth’s surfaceUneven heating of the Earth’s surface– SeasonsSeasons– The Coriolis effectThe Coriolis effect– The amount of solar radiation reaching The amount of solar radiation reaching

the earth’s surface over a given period of the earth’s surface over a given period of timetime

– Convection cells created by areas of warm Convection cells created by areas of warm ocean waterocean water

Coriolis EffectCoriolis Effect

• Once an air mass Once an air mass is set in motion (by is set in motion (by pressure pressure gradients) it gradients) it undergoes an undergoes an apparent apparent deflection from it’s deflection from it’s path due to the path due to the rotation of the rotation of the earthearth– Coriolis force at Coriolis force at

Equator is zeroEquator is zero

Trade WindsTrade Winds• Caused by Coriolis effectCaused by Coriolis effect

• Determined shipping routes during the Age of Determined shipping routes during the Age of SailSail

Human ActivityHuman Activity

• Human activities that affect the Human activities that affect the climate:climate:– DeforestationDeforestation– UrbanizationUrbanization– Heat island effectsHeat island effects– Release of pollutantsRelease of pollutants– Burning fossil fuelsBurning fossil fuels– Produce acid rainProduce acid rain

Major Climate PeriodsMajor Climate PeriodsTime Time periodperiod

EventsEvents

2,000,002,000,000 – 0 – 12,000 12,000 BCEBCE

Pleistocene Ice Age: Characterized by large Pleistocene Ice Age: Characterized by large advancing and retreating glaciers over North advancing and retreating glaciers over North America, Europe, and Asia; Global temperatures 7America, Europe, and Asia; Global temperatures 7°°F – F – 99°°F cooler than todayF cooler than today

12,000 – 12,000 – 3,000 3,000 BCEBCE

Gradual warming trend beganGradual warming trend began

10,000 – 8,500 BCE: cooling period believed to be 10,000 – 8,500 BCE: cooling period believed to be caused by fresh water draining into the North Atlantic caused by fresh water draining into the North Atlantic and changing ocean currentsand changing ocean currents

5,000 – 3,000 BCE: Climate Optimum, warmest 5,000 – 3,000 BCE: Climate Optimum, warmest period; Many ancient civilizations flourished here.period; Many ancient civilizations flourished here.

3,000 - 3,000 - 750 BCE750 BCE

Cooling period, caused sea levels to drop 6 – 10 feet Cooling period, caused sea levels to drop 6 – 10 feet (many islands formed) and high latitude and altitude (many islands formed) and high latitude and altitude glaciers to formglaciers to form

Brief warming period from 2000 – 1500 BCEBrief warming period from 2000 – 1500 BCE

Major Climate PeriodsMajor Climate PeriodsTime Time periodperiod

EventsEvents

750 BCE 750 BCE – 900 CE– 900 CE

Warming up to 150 BCEWarming up to 150 BCE

Cooling began during Roman EmpireCooling began during Roman Empire

-Nile River and Black Sea froze-Nile River and Black Sea froze

900 – 900 – 1550 CE1550 CE

Little Climate Optimum: (to 1200 CE) warm period – Little Climate Optimum: (to 1200 CE) warm period – Viking ExpansionViking Expansion

Followed by cooling period with record floods, Followed by cooling period with record floods, droughts, extreme season fluctuations up to 1400’s droughts, extreme season fluctuations up to 1400’s

1550 – 1550 – 1850 CE1850 CE

Little Ice Age: coldest global temperaturesLittle Ice Age: coldest global temperatures

Temperatures in the northern hemisphere were Temperatures in the northern hemisphere were about 2about 2°°F colderF colder

1850 – 1850 – PresentPresent

General warming trend – due largely to humansGeneral warming trend – due largely to humans

Atmosphere Circulation Atmosphere Circulation CellsCells

• Hadley Air Circulation CellsHadley Air Circulation Cells

• Ferrel Air Circulation CellsFerrel Air Circulation Cells

• Polar Air Circulation CellsPolar Air Circulation Cells

Help determine biomes and biogeography of the Earth

WindsWinds• Isobar Map – shows wind speeds over a Isobar Map – shows wind speeds over a

geographic areageographic area– The closer the bars are the greater the wind The closer the bars are the greater the wind

speedspeed

Hadley Air Circulation CellsHadley Air Circulation Cells• Air is heated at the equator, rises and Air is heated at the equator, rises and

expands north and southexpands north and south

Ferral Air Circulation CellsFerral Air Circulation Cells• Develop between 30N and 30S latitudeDevelop between 30N and 30S latitude

• Mid-latitude climates have servere winters Mid-latitude climates have servere winters and cool summers, defined seasonsand cool summers, defined seasons

Polar Air Circulation CellsPolar Air Circulation Cells• Icy dry air from poles meets moist tropical air Icy dry air from poles meets moist tropical air

from mid-latitudesfrom mid-latitudes• Air returns to the poles, cooling and sinking, Air returns to the poles, cooling and sinking,

causing precipitationcausing precipitation• Very little liquid water – most is ice or snowVery little liquid water – most is ice or snow

The whole picture…The whole picture…

Hurricanes, Cyclones, Hurricanes, Cyclones, TyphoonsTyphoons• Same thing different placeSame thing different place

– Hurricanes – Atlantic and NE PacificHurricanes – Atlantic and NE Pacific– Cyclones – S Pacific and Indian OceansCyclones – S Pacific and Indian Oceans– Typhoons – NW PacificTyphoons – NW Pacific

• Most severe weather on planetMost severe weather on planet– Begin with collision of warm ocean areas Begin with collision of warm ocean areas

where trade winds convergewhere trade winds converge

• Cyclonic flow is initiated by Coriolis Cyclonic flow is initiated by Coriolis effecteffect

TornadoTornado• Swirling air masses with wind speeds up to 300mphSwirling air masses with wind speeds up to 300mph• Occur primarily over landOccur primarily over land• Require vertical shear of the horizontal winds Require vertical shear of the horizontal winds

(change in wind speed and direction with height)(change in wind speed and direction with height)• Last less than one hour – typically Last less than one hour – typically

MonsoonsMonsoons

• Strong violent winds that change Strong violent winds that change direction with the seasonsdirection with the seasons

• Blow from land to sea in winter Blow from land to sea in winter

• Blow from sea to land in summerBlow from sea to land in summer

• Summer monsoons provide large Summer monsoons provide large quantities of rainquantities of rain

Normal StateNormal State• Walker circulation – easterly trade winds Walker circulation – easterly trade winds

move water and air warmed by the sun move water and air warmed by the sun toward the westtoward the west

El Niño El Niño • Air Pressure in the S Pacific Changes direction, Air Pressure in the S Pacific Changes direction,

trade winds reverse direction trade winds reverse direction pushes pushes thermocline deeper and decreases upwellingthermocline deeper and decreases upwelling

• Results in a shift of prevailing rain patternResults in a shift of prevailing rain pattern

La Niña La Niña • Trade winds are stronger than normal Trade winds are stronger than normal

increased upwellingincreased upwelling

• Brings opposite effects of El Niño, warmer Brings opposite effects of El Niño, warmer and drier weather.and drier weather.