Physical GeographyPhysical Geography

Class 9 – Class 9 –

Earth’s AtmosphereEarth’s Atmosphere

Structure and CompositionStructure and Composition

How big is the atmosphere?How big is the atmosphere?

Atmosphere extends to 32,000 km Atmosphere extends to 32,000 km (20,000 mi) from surface(20,000 mi) from surface

Thermopause is at 480 km (300 mi)—top Thermopause is at 480 km (300 mi)—top of the principal atmosphere of the principal atmosphere

100 km??100 km??

Atmospheric Atmospheric PressurePressure

Figure 3.3

Layers of the AtmosphereLayers of the Atmosphere

Atmospheric TemperatureAtmospheric Temperature

TroposphereTroposphere– Surface to 18 km (11 mi)Surface to 18 km (11 mi)– 90% mass of atmosphere90% mass of atmosphere– Normal lapse rate – average cooling at rate of Normal lapse rate – average cooling at rate of

6.4 C°/km (3.5 F°/1000 ft)6.4 C°/km (3.5 F°/1000 ft)– Environmental lapse rate – actual local lapse Environmental lapse rate – actual local lapse

raterate

Atmospheric TemperatureAtmospheric Temperature

ThermosphereThermosphere– Roughly same as heterosphereRoughly same as heterosphere– 80 km (50 mi) outward80 km (50 mi) outward– Temperature risesTemperature rises

Atmospheric TemperatureAtmospheric Temperature

MesosphereMesosphere– 50 to 80 km (30 to 50 mi)50 to 80 km (30 to 50 mi)– Temperature fallsTemperature falls

Atmospheric TemperatureAtmospheric Temperature

StratosphereStratosphere– 18 to 50 km (11 to 31 mi)18 to 50 km (11 to 31 mi)– Temperature risesTemperature rises

Composition of AirComposition of Air

Variable Atmospheric Components  Variable Atmospheric Components  

Impurities and Pollutants in TroposphereImpurities and Pollutants in Troposphere

Harmful Gases and Other ChemicalsHarmful Gases and Other Chemicals

VirusesViruses

Water VaporWater Vapor

Carbon DioxideCarbon Dioxide

Aerosols/ParticulatesAerosols/Particulates

ParticulatesParticulates

Sources of AerosolsSources of Aerosols

Southern California WildfiresSouthern California Wildfires

Figure 3.8

USGSUSGS

Water VaporWater Vapor

Can you see this invisible gas?Can you see this invisible gas?

Variations in Atmospheric Variations in Atmospheric CompositionComposition

IonosphereIonosphere– Absorbs cosmic rays, gamma rays, X-rays, Absorbs cosmic rays, gamma rays, X-rays,

some UV rayssome UV rays

Ozonosphere (ozone layer)Ozonosphere (ozone layer)– Part of stratospherePart of stratosphere

– Ozone (OOzone (O33) absorbs UV energy and converts ) absorbs UV energy and converts

it to heat energyit to heat energy

Atmospheric Atmospheric PressurePressure

Figure 3.3

The endThe end

Normal Lapse RateNormal Lapse Rate