Chapter 3Chapter 3

Introduction to the AtmosphereIntroduction to the Atmosphere

Supplies oxygen for humans & animalsSupplies oxygen for humans & animals Supplies carbon dioxide (COSupplies carbon dioxide (CO22) for plants) for plants

Helps maintain water supplyHelps maintain water supply Insulates Earth from extreme temperaturesInsulates Earth from extreme temperatures Insulates Earth from ultraviolet radiation -Insulates Earth from ultraviolet radiation -

(UV) rays(UV) rays

Atmosphere makes life possible on Atmosphere makes life possible on EarthEarth

Introduction to the AtmosphereIntroduction to the Atmosphere

Composition of the AtmosphereComposition of the Atmosphere Vertical Structure of the AtmosphereVertical Structure of the Atmosphere The Ozone ProblemThe Ozone Problem Weather and ClimateWeather and Climate

AirAir

Air is not a gas; it is a mixture of gasesAir is not a gas; it is a mixture of gases 2 main gases are oxygen and nitrogen2 main gases are oxygen and nitrogen Pure air is colorless and odorlessPure air is colorless and odorless Clouds are made up primarily of water Clouds are made up primarily of water

vaporvapor

Composition of Composition of the Atmospherethe Atmosphere

3 Main Gases:3 Main Gases:– Nitrogen = 78Nitrogen = 78– Oxygen = 21Oxygen = 21– Argon = 1Argon = 1

These are approximate numbers that we will use in this class.

Atmospheric GasesAtmospheric Gases

ParticulatesParticulates

Larger particulates are water and iceLarger particulates are water and ice Dust and pollenDust and pollen ChemicalsChemicals AerosolsAerosols Some are natural – some are human sourceSome are natural – some are human source i.e. industrial, automotive, firesi.e. industrial, automotive, fires

Particulate matter in the atmosphere is from both natural and human sources. For example: pollen is natural and automotive exhaust (CO2) is human.

ParticulatesParticulates

The atmosphere provides The atmosphere provides vertical and horizontal vertical and horizontal transport of particulatestransport of particulates

Particulates can be Particulates can be transported great transported great distances – even globally distances – even globally by the atmosphereby the atmosphere

Particulates affect weather Particulates affect weather and climate:and climate:

Cloud formationCloud formationAbsorption & Absorption &

reflection of sunlightreflection of sunlight

Earth

Atmosphere

Dust Storms

Atmospheric ParticulatesAtmospheric Particulates

Dodge City, KansasMay 29, 2004

Libya-SicilyMay 29, 2004

Mt. St. HelensMt. St. Helens8:32 Sunday morning, May 18, 1980 8:32 Sunday morning, May 18, 1980

NYC 9/11NYC 9/11

Vertical Structure of the Vertical Structure of the AtmosphereAtmosphere

Temperature varies and rises or falls at Temperature varies and rises or falls at different altitudesdifferent altitudes

Pressure is greater near the surface of Pressure is greater near the surface of the earththe earth

Composition of gases is different at Composition of gases is different at different structural levels in the different structural levels in the atmosphereatmosphere

The vertical structure of the atmosphere determines:

Thermal Layers of Thermal Layers of thethe

AtmosphereAtmosphere

EExospherexosphere TThermospherehermosphere MMesosphereesosphere SStratospheretratosphere TTroposphereroposphere

TemperatureTemperatureVariation with Variation with

ElevationElevation

From sea level through From sea level through the troposphere temp the troposphere temp decreasesdecreases

At 12 miles it starts to At 12 miles it starts to increaseincrease

At 30 miles bottom of At 30 miles bottom of mesosphere it starts to mesosphere it starts to decrease againdecrease again

Minimum at 50 milesMinimum at 50 miles

Vertical Thickness of AtmosphereVertical Thickness of Atmosphere

Not a consistent Not a consistent depth/thicknessdepth/thickness

Over the equator, Over the equator, the troposphere is the troposphere is deepest/thickestdeepest/thickest

Over the poles, it is Over the poles, it is shallowest/thinnest shallowest/thinnest

N

S

Atmospheric PressureAtmospheric Pressure

Can be thought of as the weight of overlying Can be thought of as the weight of overlying layers of air compressing the lower layers layers of air compressing the lower layers

Atmospheric pressure is highest at sea level Atmospheric pressure is highest at sea level and decreases with altitudeand decreases with altitude

As you climb a mountain the atmospheric As you climb a mountain the atmospheric pressure decreases. We say the air is pressure decreases. We say the air is thinner.thinner.

Atmospheric PressureAtmospheric Pressure

Spatial Location of Atmospheric Spatial Location of Atmospheric MassMass

Atmospheric Atmospheric CompositionComposition

Good mix = uniform distribution

Not mixed = layered

The Ozone ProblemThe Ozone Problem

Natural Atmospheric OzoneNatural Atmospheric Ozone Destruction of Ozone by Destruction of Ozone by

Chlorofluorocarbons (CFCs)Chlorofluorocarbons (CFCs) The Antarctic Ozone HoleThe Antarctic Ozone Hole

Vertical Vertical StructureStructure

of the of the AtmosphereAtmosphere

Note: the Ozone Layer overlaps the Troposphere – the zone we live in!

Natural OzoneNatural Ozone

Ozone Destruction by CFCsOzone Destruction by CFCs

Ozone DepletionOzone Depletion

Weather and ClimateWeather and Climate

Elements of Weather and ClimateElements of Weather and Climate Controls of Weather and ClimateControls of Weather and Climate

Elements & ControlsElements & Controls

TemperatureTemperature PressurePressure WindWind Moisture ContentMoisture Content

LatitudeLatitude Distribution of land and Distribution of land and

waterwater General circulation of General circulation of

the atmospherethe atmosphere General circulation of General circulation of

the oceansthe oceans ElevationElevation Topographic BarriersTopographic Barriers StormsStorms

ELEMENTS CONTROLS

LatitudeLatitude

General Circulation of the AtmosphereGeneral Circulation of the Atmosphere

Figure 3-14

General Circulation of the OceansGeneral Circulation of the Oceans

ElevationElevation

Topographic BarriersTopographic Barriers

StormsStorms