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Introduction to atmosphere, weather, and climate

February 20, 2010

The Atmosphere

Where is the atmosphere?– Everywhere!

Completely surrounds Earth

What makes up the atmosphere?

––ArgonArgon–– Inert gasInert gas

1%1%

Variable GasesVariable Gases–– Influential for _________ & _________Influential for _________ & _________

____________________________–– Source of all clouds and precipitation; heating/cooling Source of all clouds and precipitation; heating/cooling

____________________________–– Absorbs infrared radiation = warms lower Absorbs infrared radiation = warms lower

atmosphereatmosphere

Importance of our atmosphereMakes life possible on Earth

1.2.3.4.

4 Layers of the Atmosphere

Thermosphere

We live in the _________Troposphere

TropopauseStratosphere

It gets colder as you go up in the troposphere because you get farther from the earth, the main heat source.

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Troposphere

Lowest region of the atmosphereLowest region of the atmosphereContains Contains ½½ of the Earthof the Earth’’s atmospheres atmosphereTemperature ____________ with an Temperature ____________ with an _______________________________________________ occurs in this layer_____________ occurs in this layerExtends from surface to about 11 Extends from surface to about 11 milesmiles

Depth of tropopause

Between the troposphere & Between the troposphere & Stratosphere is the tropopauseStratosphere is the tropopauseHeight is variableHeight is variableVaries in time & placeVaries in time & place–– Tropical regionsTropical regions–– PolesPoles–– SummerSummer–– WinterWinter–– Warm/cold air massesWarm/cold air masses

Stratosphere

Temperature ________ with an ____________________– Called a __________________Extends from about 11 miles to 30 miles

Why is there a temperature inversion in the stratosphere?

–

–

Mesosphere

Temperature ________ with an _______________Where meteors burn up while entering the Earth’s atmosphere

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Thermosphere

First exposed to the Sun's radiation and so is first heated by the Sun– Air is so thin that a small increase in

energy can cause a large increase in temperature

Contains the ionosphere– Region of the atmosphere filled with

charged particles– Makes radio communication possible

What is atmospheric pressure?

– Taller the column of air above an object, the greater the air pressure exerted on that object

Density & Pressure

Air is highly compressibleAir is highly compressibleLower layers of atmosphere are Lower layers of atmosphere are compressed by air above itcompressed by air above it–– This compression increases pressure & This compression increases pressure &

density of the lower layers of the density of the lower layers of the atmosphereatmosphere

Our atmosphere produces an infinite variety of conditions and phenomena know as weather

What is the difference between weather and climate?Weather–

Climate–

Weather that we expect to occur– Based on long time average of day-to-day weather

conditions, variations, and extremesElements of weather & climate– Temperature, moisture content, pressure, and wind– The basic ingredients of weather and climate

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Examples of Weather

– Temperature, cloud cover, precipitation, humidity

Climate: _________________________30 year average in U.S.

precipitation

temperature

seasonal variations in monthly averages

wind speed and direction

cloud cover

Use climograph to display climate data

Climograph

What kind of weather would you expect?

January in Barrow, Alaska

June in Mobile, Alabama

Meteorology -

condition of atmosphere at a given time for a given areatemperature, pressure, wind, moisture

Climatology -

usually over past 30 years

What controls weather & climate?

Semipermanent attributes of Earth that influence climate & weather1.2.3.4.5.6.7.

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Latitude

Most basic control of ___________– If this were the only control of

temperature on Earth, then isotherms would run east to west

Temperature _________ as latitude ___________– Because solar insolation decreases with

an increase in latitude

Land-Water Contrast

Water has a much higher specific heat than land– This means that land heat and cools

quicker than water– This also means that it takes a lot of time

and heat energy to change the temperature of water

New Orleans, LA New Orleans, LA –– Average January temp = 51.3 Average January temp = 51.3 °°FF–– Average July temperature = 81.9 Average July temperature = 81.9 °°FF

Fargo, NDFargo, ND–– Average January temp = 5.9 Average January temp = 5.9 °°FF–– Average July temp = 71.1 Average July temp = 71.1 °°FF

Land-Water Contrast

Fargo, ND has a 65.2 °F difference between January & July temperatures– Very continental climate, hot in the summer

and very cold in the winterNew Orleans, LA has a 30.6 °F difference between January & July temperatures– Temps are influenced by the Gulf of Mexico

Wind Patterns & Air Masses

Semipermanent pattern of major wind Semipermanent pattern of major wind and pressure systems dominates the and pressure systems dominates the tropospheretroposphere

Wind Patterns & Air Masses

Dominant wind direction influences local temperature patternsDominant wind direction for midlatitudes is from the _________– This means that air masses tend to move from the

_____________

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Ocean Currents

Assist in heat transfer – Move warm water poleward & cool

water toward the equatorWarm currents are found off the eastern coasts of continentsCool currents occur off western coasts

Ocean Currents

Altitude/Elevation

Generally speaking, temperature decreases with increased elevationHigh elevation stations have a similar temperature pattern as nearby stations as a lower elevation– Consistently cooler

Topographic Barriers

Effect climate & weather by diverting wind flowSide of mountain range facing the wind is called the ______________Side of mountain range that is sheltered is called the _____________

Storms

Can affect a wide area or be localizedResult from interactions among other climate controls

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Atmosphere: blanket of air surrounding earth1. 2. 3.

Without our atmosphere: cold, quiet, cratered place

Dynamic: currents and circulation cells

Atmosphere important in equalizing temperature and pressure by transfer of heat, energy, and moisture around world

The Sun & InsolationThe Sun & Insolation

The SunThe Sun

Most important source of energy for EarthMost important source of energy for Earth’’s s atmosphereatmosphere

The Sun (cont.)The Sun (cont.)

Provides an immense and continuous flow Provides an immense and continuous flow of radiant energy of radiant energy –– Electromagnetic wavesElectromagnetic waves

UV, visible, infraredUV, visible, infraredAlmost all is shortwave (Almost all is shortwave (uvuv & visible)& visible)

Dispersed in all directionsDispersed in all directions....Less than one billionth of total solar Less than one billionth of total solar output reaches Earthoutput reaches Earth’’s atmospheres atmosphere

Driving force behind _________ and ____________

Total insolation is a function of _________________

Controlled primarily by ___________

How bright the sun shines

Factors affecting intensity

1.

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1. Angle of the sun’s rays affects intensity of insolation

(Latitude and season affect angle of sun’s rays)

Latitudinal comparison Angle of incidence Surface area

covered

How bright the sun shines

Factors affecting intensity

1. Angle of the sun’s rays

2.

2. Atmospheric transparency affects intensity of insolation

100% at top of atmosphere

80% can reach ground on clear day

15% absorbed by molecules and dust

5% scattered or reflected

0-45% reaches ground on cloudy day

5-20% absorbed by clouds

30-60% reflected by clouds

How bright the sun shines

Factors affecting intensity

1. Angle of the sun’s rays

2. Atmospheric transparency

3.

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3. Altitude affects intensity of insolation

Mt. Everest, 5.5 mi high

How long the sun shines during the day

Depends on _______ and ________

~15 hrs12 hrs.~9 hrs.12 hrs.S.Mid-lat

24 hrs.12 hrs.0 hrs.12 hrs.S. Pole

12 hrs.12 hrs.12 hrs.12 hrs.Equator

~9 hrs.12 hrs.~15 hrs12 hrs.N.Mid-Lat

0 hrs.12 hrs.24 hrs.12 hrs.N.Pole

December Solstice

Fall Equinox

June Solstice

SpringEquinox

Duration of Insolation

Tropics: sun is directly overhead twice a year

Low latitudes

Mid-latitudes: sun never directly overhead

Mid-latitudes: sun never directly overhead

High-latitudes

High-latitudes

TROPICS: insolation high year round due to high sun angle and constant duration

Mid-latitudes: insolation highest at summer solstice due to higher sun angle and longer day, lowest at winter solstice due to low angle and short day

High latitudes: insolation highest at summer solstice due to 24 hour duration low angle sun, extremely low to none at winter solstice

BelowBelowhorizonhorizon

HorizonHorizon

LowLow

HorizonHorizon

AngleAngle

PolesPolesEquatorEquator

HighHigh--

HighHigh

HighHigh--

HighHigh

AngleAngle

ZeroZero0 hrs.0 hrs.HighHigh--12 hrs.12 hrs.WinterWinterSolsticeSolstice

LowLow12 hrs.12 hrs.HighHigh12 hrs.12 hrs.Fall Fall EquinoxEquinox

HighHigh24 hrs24 hrsHighHigh--12 hrs.12 hrs.Sum. Sum. SolsticeSolstice

LowLow12 hrs.12 hrs.HighHigh12 hrs.12 hrs.Spring Spring EquinoxEquinox

TotalTotalDurationDurationTotalTotalDurationDuration

Seasonal variation in insolation at top of atmosphere

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Total annual insolation __________________

Seasonality _________________________

Insolation that reaches the Earth can be…

1.

2. Proportion reflected = Does not heat Earth

High albedo Low albedo

Dark surfaces are more efficient absorbers

Earth radiates in longer wavelengths90% of this radiation absorbed by atmosphere

Greenhouse gases

Clouds also absorb outgoing longwave energy

Atmosphere is warm, therefore it also radiates energy

Counter radiation directed back to Earth

Absorbed radiation heats the earth. The earth then radiates energy back out. EarthEarth’’s energy balances energy balance

There is a balance between the total There is a balance between the total amount of insolation received by Earth & amount of insolation received by Earth & atmosphere & total amount radiation atmosphere & total amount radiation returned to spacereturned to space

Net RadiationNet Radiation

Incoming Incoming –– Outgoing radiation energyOutgoing radiation energy

Highest at low latitudes = surplus energyHighest at low latitudes = surplus energyLowest at high latitudes = deficit of Lowest at high latitudes = deficit of energyenergy

How does heat move from How does heat move from one place to another?one place to another?

1.1.

2.2.

3.3.

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How can earth move energy from surplus to deficit areas? (Methods of heat transfer) 1.

All bodies above -460°F (-273°C) (0° Kelvin) radiate energy.

Lower body temperature, longer wavelength.

Thermal infrared wavelength energy radiated by Earth heats troposphere.

ConductionConductionHeat that is transferred from one part of a stationary Heat that is transferred from one part of a stationary body to another when the two are in contactbody to another when the two are in contactEarthEarth--air interfaceair interface–– Land heats up Land heats up –– transferred to lower atmospheretransferred to lower atmosphere

For this – only important at earth-air interface

ConvectionConvection

Heat transferred from one point to Heat transferred from one point to another by a moving substanceanother by a moving substance

Convection-Vertical currents

Advection-Horizontal currents

TemperatureTemperature

Measurement of sensible heat/energyMeasurement of sensible heat/energyTemperature is an expression of the Temperature is an expression of the degree of hotness or coldness of a degree of hotness or coldness of a substancesubstanceThere is a link between troposphere There is a link between troposphere temperature and Earth surface temperature and Earth surface conditionsconditions–– The air temperature represents the The air temperature represents the

balance between insolation and terrestrial balance between insolation and terrestrial radiationradiation

Temperature Depends On …

1. Insolation

altitude

seasonatmospheric transparency

latitudeangle of sun’s rays

Intensity x Duration

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Temperature depends on …

2. Reflectivity (albedo) of surface

Temperature depends on …

3. Whether surface is land or water (continentality)

Relative rates of heat flow into soil and water

Most land has low albedo. It absorbs radiation and heats up

Relative rates of heat flow into soil and water

Soil 5°C 10°C 20°C 40°C

Water heats up (and cools down) slower than land

CONTINENTALITY

Why does water heat and cool Why does water heat and cool slower than land?slower than land?

1.1.

2.2.

3.3.

4.4.

5.5.