The Earth’s AtmosphereThe Earth’s Atmosphere1

April 4, 2011

Agenda: SILENCE YOUR CELL PHONE!!• Red-Rock Canyon FT – April 9th - - Saturday

• Sign-up sheets Today- Thursday• RRC itinerary online by Tuesday

• Geologic Time – Lecture “What you need to know”• PPt slides to # 38 “What is the importance of radiometric dating………..• The geologic time scale

• eons, eras, periods• Monday, Wednesday Labs

• Atmosphere – I will have labs for students

The AtmosphereThe Atmospherethin layer of gas that covers thethin layer of gas that covers theentire earth --- (a sea of gasses)entire earth --- (a sea of gasses)

lets us breathelets us breathekeeps us coolkeeps us cool

very thin (approx. 65 milesvery thin (approx. 65 miles))

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Atmosphere: a mixture of gasses surrounding a planet (sea of gasses)The earth’s atmosphere:Nitrogen (N) = 78.08%Oxygen (O) = 20.95%Argon (Ar) = .93%Other:Water vapor (H2O) = 1%-4%Carbon dioxide (CO2) = .035%Helium (He)Methane (CH4)Krypton (Kr)Nitrous oxide (N2O)Hydrogen (H2)Ozone (O3)dust and pollen particles

measured asdry air

I I to breathe our atmosphere.to breathe our atmosphere.

I will get an A on my exams and quizzes.I will get an A on my exams and quizzes.

Discuss with a friend:Discuss with a friend:1.1.Define an atmosphere (not the earth’s).Define an atmosphere (not the earth’s).2. What is the composition of the earth’s2. What is the composition of the earth’s atmosphere?atmosphere?3. What are the two major compounds3. What are the two major compounds that represent less than 1% of gassesthat represent less than 1% of gasses in the atmosphere?in the atmosphere?

Atmospheric Layers and TemperatureAtmospheric Layers and Temperature

TT

TT

TT

TTThermosphereThermosphere

MesosphereMesosphere

StratosphereStratosphere

TroposphereTroposphere7 mi7 mi

30 mi30 mi

50 mi

TT

TT

TT

T

HomosphereComposition of the

atmosphere isuniform. .

HeterosphereAtmosphere is

layered by molecularweight and electric

charge.

I I to breathe our atmosphere.to breathe our atmosphere.Discuss with a friend:Discuss with a friend:

1.1.Draw a diagram showing the layeringDraw a diagram showing the layering of the earth’s atmosphere.of the earth’s atmosphere.2. Show the temperature relations between2. Show the temperature relations between each atmospheric layer.each atmospheric layer.3. Define the differences between the3. Define the differences between the homospherehomosphere and and heterosphere heterosphere zones zones of the atmosphere. of the atmosphere.

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TroposphereTroposphere• lowest layer of the atmospherelowest layer of the atmosphere• temperature decreases with altitudetemperature decreases with altitude

• environmental temperature lapse rate (ETL)environmental temperature lapse rate (ETL)• ETL – temperature decreases with altitudeETL – temperature decreases with altitude• ETL averages 6.4 ETL averages 6.4 00C/1000 m or 3.5 C/1000 m or 3.5 00F/1000 ft.F/1000 ft.

• all storm and turbulent activity takes placeall storm and turbulent activity takes place• average thickness is 12 km from surfaceaverage thickness is 12 km from surface• thickest at the equator (16 km, 10 mi.)thickest at the equator (16 km, 10 mi.)• thinnest at the polar regions (6 km, 4 mi.)thinnest at the polar regions (6 km, 4 mi.)• responsible for the greenhouse effectresponsible for the greenhouse effect

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StratosphereStratosphere• Layer lies between the troposphere andLayer lies between the troposphere and mesosphere.mesosphere.• contains strong, persistent winds that blowcontains strong, persistent winds that blow from west to east.from west to east.• Temperature increases as altitude increases.Temperature increases as altitude increases.• contains the ozone layer (Ocontains the ozone layer (O33).).

• Stratosphere heats up because the ozone absorbsStratosphere heats up because the ozone absorbs the sun’s radiation.the sun’s radiation.

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Ozone layer (O3)O

OO

• three oxygens bonded together• O2 (molecular oxygen) + O (elemental oxygen) combine through ultra-violet energy bombardment ------ continuous cycle

• protects us from harmful ultra-violet radiation• absorbs 97% of UV radiation• concentrated in the upper stratosphere

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MesosphereMesosphere• layer between the thermosphere and layer between the thermosphere and stratospherestratosphere• 30 to 50 miles above the earth30 to 50 miles above the earth• temperature decreases with altitudetemperature decreases with altitude• has the coldest temperature of -90 has the coldest temperature of -90 00CC

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ThermosphereThermosphere

• first layer to be heated by the sunfirst layer to be heated by the sun

• uppermost layer of atmosphereuppermost layer of atmosphere

• temperature increases with altitudetemperature increases with altitude

• Where’s the upper boundary?Where’s the upper boundary?

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What is What is incomingincoming solasolar radiar radiationtion? (? (ininsolasolationtion))• energy the earth receives from the sunenergy the earth receives from the sun• travels 300,000 km/sec (186,000 mi/sec)travels 300,000 km/sec (186,000 mi/sec)• travels in “wave motion”travels in “wave motion”• Sun rays comprise the electromagnetic spectrum.Sun rays comprise the electromagnetic spectrum.

Electromagnetic Spectrum (EM scale)Electromagnetic Spectrum (EM scale)

Wavelengths the Wavelengths the human eye can see eye can see R O Y G B I V R O Y G B I V

Not harmfulNot harmful Very harmfulVery harmfulLong WavesLong Waves Short WavesShort Waves

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I I to breathe our atmosphere.to breathe our atmosphere.1.1.Describe at least 2 major characteristicsDescribe at least 2 major characteristics of each layer in the earth’s atmosphere.of each layer in the earth’s atmosphere.2. Define 2. Define insolation.insolation.3. Draw the EM scale and label the following:3. Draw the EM scale and label the following:

types of long wave radiationtypes of long wave radiationtypes of short wave radiationtypes of short wave radiationthe visible light spectrumthe visible light spectrum

4. 4. What wavelengths are harmful to life?What wavelengths are harmful to life?

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ThermosphereThermosphere

MesosphereMesosphere

StratosphereStratosphere

TroposphereTroposphere

most short waves most short waves are absorbedare absorbed

UV waves are absorbedUV waves are absorbedand make ozone (Oand make ozone (O33))

Most EM is longwaveMost EM is longwavebefore hitting the surfacebefore hitting the surface(visible and IR)(visible and IR)

OZONEOZONE

insolation

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H2O –the most remarkable substance on earth!

Water exists in ALL three states on the earth’s surface.

SOLID LIQUID GAS

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ICE

LIQUID

WATERVAPOR Moving from

an orderedstate to a lessordered state,

heat is absorbed.

Energy is taken in.

Moving froma less orderedstate to a moreordered state,

heat is released.

Energy moves out.

Latent heat (“hidden heat”)• the amount of heat released or absorbed during a phase change (solid to a liquid to a gas)

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Heat Absorbed

Heat Released

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Examples of latent heat:Water is evaporated off your skin surface and youfeel cool. Why do you feel cool?

As water evaporates from your skin surface, heatenergy is absorbed from your skin cooling your body.

moving from a liquid state to a vapor state(latent heat is absorbed)

Clouds are formed through the process of condensation (changing water vapor to a suspendedliquid).

As water vapor cools in the upper atmosphere,it condenses to liquid releasing latent heat.

So, where does the latent heat go?20

Absorbed and released latent heatis circulated throughout the earth’s

atmosphere, giving rise to clouds andvarious forms of precipitation.

To understand the formation of clouds andprecipitation, one needs to understand:

Humidity

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The Greenhouse EffectAdiabatic Processes

ConvectionCondensation

I I to breathe our atmosphere.to breathe our atmosphere.1.1.What is latent heat, and how does latentWhat is latent heat, and how does latent heat interact with various phase changesheat interact with various phase changes of water?of water?2. Describe the differences between 2. Describe the differences between humidityhumidity and and relative humidityrelative humidity..3. 3. What conditions are necessary regardingWhat conditions are necessary regarding atmospheric temperature and water vaporatmospheric temperature and water vapor

to reach a dew point?to reach a dew point?

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• How do you feel on a hot, humid day?Humidity:

• Humidity represents the amount of water vapor in the air.• The amount of water vapor in the atmosphere is dependent on air temperature.

Relative Humidity (RH):• RH compares the amount of water vapor in the air to what that parcel of air can hold according to a particular temperature.

Dew Point:• At dew point, the air is saturated with water vapor (can’t hold anymore), and the air condenses. 23

RelativeHumidity Temperature

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parcelof air

parcelof air

What happens to both humidity and relative humidityas a function of atmospheric air temperature?

% of H2O vapor increases withincrease in air temperature.

condensing

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How does absorbed insolation keep theatmosphere warm?

The GreenhouseEffect

Visible and UV lightVisible and UV light““insolation”insolation”

IR heat wavesIR heat wavesare trapped are trapped inside the inside the

greenhouse.greenhouse.

The Greenhouse Effect“counterradiation”

Temperature

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.07%

.03%

trace

trace

How do greenhouse gasses contribute to counterradiation?

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Carbon dioxide absorbing infrared EM Carbon dioxide absorbing infrared EM • Infrared EM vibratesInfrared EM vibrates COCO22

• COCO22 absorbs IR EM. absorbs IR EM.• IR is released toIR is released to the earth’s surface.the earth’s surface.

AtmosphereAtmosphereheats up!heats up!

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How does the greenhouse effect work in our atmosphere?How does the greenhouse effect work in our atmosphere?

SunCOCO22 absorbs IR waves. absorbs IR waves.

Visible & UVVisible & UV

InfraredInfrared

IR returnsIR returnscounterradiation.counterradiation.

SurfaceSurface

AtmosphereAtmosphereHeatsHeats

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What do you think is the role of H2O vapor in the atmosphere?

Do we need the greenhouse effect (GHE)?• Would global temperatures be -15 0C without the greenhouse effect?• Is the greenhouse effect NATURAL?• Does the GHE act as a “blanket” keeping the earth warm?• Is the greenhouse effect considered a contributor of global warming?• The global warming debate considers:

• Is the increase in CO2 natural?• Is the increase in CO2 man-made?• What is the role of water vapor?

NO!

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I I to breathe our atmosphere.to breathe our atmosphere.

1.1.What % of EM is reflected back to space,What % of EM is reflected back to space, and what % is absorbed at the earth’s surface?and what % is absorbed at the earth’s surface?2. How is the earth’s albedo defined? 2. How is the earth’s albedo defined? 3. What are greenhouse gasses? Explain how3. What are greenhouse gasses? Explain how the greenhouse effect warms the earth.the greenhouse effect warms the earth.4. Why is the greenhouse effect important to 4. Why is the greenhouse effect important to the survival of life on earth?the survival of life on earth?

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Formation of Clouds

unique formation?

• adiabatic principle• condensation

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Adiabatic (ey-di-uh-BA-tic) processes• describes how the temperature of an air parceldescribes how the temperature of an air parcel changes as it rises and falls in the atmospherechanges as it rises and falls in the atmosphere

Air Pressure Air Pressure HigherHigher

Air PressureAir PressureLowerLower

CompressionCompression

ExpansionExpansion

WarmsWarms

CoolsCools

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Adiabatic ProcessesAdiabatic Processes

• By definition, adiabatic processes involve By definition, adiabatic processes involve NONO heat exchangeheat exchange between the parcel of air and between the parcel of air and surrounding atmosphere.surrounding atmosphere.

•CoolingCooling and and Heating Heating take place very fast.take place very fast.

• Rising air always expands and cools adiabatically.Rising air always expands and cools adiabatically.• Subsiding air is always compressed and warmedSubsiding air is always compressed and warmed adiabatically.adiabatically.

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SurfaceSurfaceTemp: 30 Temp: 30 ooCC

86 86 ooFF

1000 m1000 mTemp: 20 Temp: 20 ooCC

68 68 ooFF

2000 m2000 mTemp: 10 Temp: 10 ooCC

50 50 ooF F

Atmospheric pressure compresses air molecules, keeping air temp at 30 oC.

Decreasing air pressure causesair molecules to expand, and airtemperature decreases.Air risesAir rises

Air Air risesrises

Air molecules continue toAir molecules continue toexpand, decreasing temp.expand, decreasing temp.

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1,000 m (3,280 ft)

2,000 m (6,561 ft)

3,000 m (9,842 ft)

T= 12 0C 53 0F

T= 2 0C 35 0F

T= -8 0C 18 0F

DARDAR – – Dry Adiabatic RateDry Adiabatic Rate (when air is rising) (when air is rising) • Unsaturated air (dry air) will cool 10 Unsaturated air (dry air) will cool 10 00C/1000 mC/1000 m or 5.5 or 5.5 00F/1000 ft.F/1000 ft.

Measuring adiabatic coolingDAR (Dry Adiabatic Rate)

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What if the air is SATURATED?What if the air is SATURATED?

(MAR) Moist Adiabatic Rate (MAR) Moist Adiabatic Rate varies from 4-10 varies from 4-10 00C/1000 m, C/1000 m, as an average- as an average- 6 °C / 1000 m6 °C / 1000 m

depends on water vapor content of air (more depends on water vapor content of air (more vapor = more latent heat exchange!)vapor = more latent heat exchange!)

Why is Why is DARDAR different from different from MARMAR ? ?

1,000 m (3,280 ft)1,000 m (3,280 ft)T= 12 0C 53 0FSaturated

2,000 m (6,561 ft)2,000 m (6,561 ft)T= 6 0C 43 0F

Saturated

3,000 m (9,842 ft)3,000 m (9,842 ft)TT=0 0C 32 0F

Saturated

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I I to breathe our atmosphere.to breathe our atmosphere.

1.1.Define adiabatic processes.Define adiabatic processes.

2. Describe the differences between the2. Describe the differences between the DAR and MAR air masses.DAR and MAR air masses.

3. Describe what happens to a parcel of air3. Describe what happens to a parcel of air as it rises and falls under the influenceas it rises and falls under the influence of adiabatic processes. of adiabatic processes.

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Clouds:• Clouds are suspended water droplets, ice particles, or a mixture of both.• Cloud particles grow around a small tiny piece of solid matter (condensation nucleus) suspended in the atmosphere.

• Aerosols (condensation nuclei) originate from the ocean.

Droplets of spray are lifted by wind currents, and upon Droplets of spray are lifted by wind currents, and upon evaporation, the salt xl is left behind to form condensationevaporation, the salt xl is left behind to form condensationnuclei – the beginning of a cloud.nuclei – the beginning of a cloud.

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Formation of a Cloudand Convective Precipitation

LCL

• Saturated air mass rises and reaches the “dew point” or LCL (lifting condensation level)— forming the cloud• Continued rising and condensation add more water drops.• Convection within the cloud suspends water droplets.

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2

3

• Water drops grow in size overcoming convective updrafts and exit the cloud. This is rain.

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1 23

4

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Condensation!Condensation! Water vapor rises in the atmosphereWater vapor rises in the atmosphere

and cools (condensing) forming clouds.and cools (condensing) forming clouds.

coolscools cools

cools coolscools

Vapor risesVapor risesVapor risesVapor rises

CondensesCondenses

LCL

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Convection inside a cloudConvection inside a cloud““turbulence”turbulence”

Hot air risesHot air rises

Air cools (sinks)Air cools (sinks)

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Orographic Precipitation• Oro (mountains) -moist air moves up and over a mountain barrier.

BakersfieldBakersfieldSantaSantaBarbaraBarbara

CoastCoastRangesRanges

SierraSierraNevadaNevada

MountainsMountainsRain ShadowRain Shadow

RainRainShadow Shadow

moving moistmoving moistairair

EvaporationEvaporation

PrecipitationPrecipitation

PrecipitationPrecipitation

Dry AirDry Air

Dry AirDry Air

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.I I to breathe our atmosphere.to breathe our atmosphere.

1.1.What are condensation nuclei, and what What are condensation nuclei, and what role do they play in cloud formation? role do they play in cloud formation?

2. Describe the occurrence of precipitation in both2. Describe the occurrence of precipitation in both the convective and orographic environments.the convective and orographic environments.

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Clouds are classified based on their height and vertical development.

• high, middle, or low clouds• vertical extension into the atmosphere

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Cirrus cloudsCirrus clouds• high clouds – white and “wispy”high clouds – white and “wispy”• often have a feathery appearanceoften have a feathery appearance• appear at 20,000 feetappear at 20,000 feet• commonly appear in fair weather and pointcommonly appear in fair weather and point in the direction of air movementin the direction of air movement

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Cumulus cloudsCumulus clouds• globular individual cloud massesglobular individual cloud masses• contain a flat base (condensation level)contain a flat base (condensation level)• rising domes with anvil head topsrising domes with anvil head tops• commonly 1000 feet above the surfacecommonly 1000 feet above the surface• tremendous amounts of energy releasedtremendous amounts of energy released from condensing water vaporfrom condensing water vapor

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Stratus cloudsStratus clouds• very low “cloud sheets” very low “cloud sheets” • covers wide areas of the surfacecovers wide areas of the surface• can be considered fogcan be considered fog• a low gray blanket of moisturea low gray blanket of moisture• can bring rain or snowcan bring rain or snow

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This is the“Don’t be in the clouds

beforethe final exam”

formation.53

I I to breathe our atmosphere.to breathe our atmosphere.

1.1.How are clouds classified?How are clouds classified?

2. Give two examples of cloud types in2. Give two examples of cloud types in high, middle, and low altitudes.high, middle, and low altitudes.

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