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Physical GeographyPhysical Geography
Class 9 – Class 9 –
Earth’s AtmosphereEarth’s Atmosphere
Structure and CompositionStructure and Composition
Outline: AtmosphereOutline: Atmosphere
Definition, sizeDefinition, size
Changes in pressure, what is pressureChanges in pressure, what is pressure
Temperature layersTemperature layers
Components of clean, dry airComponents of clean, dry air
Variable ComponentsVariable Components
QuestionsQuestions
What is “air”?What is “air”?
Why does air stay where it is?Why does air stay where it is?
Is air always the same stuff no matter Is air always the same stuff no matter where you go on Earth? Up in where you go on Earth? Up in atmosphere?atmosphere?
What aspects/characteristics of air change What aspects/characteristics of air change on a daily basis? From place to place?on a daily basis? From place to place?
AtmosphereAtmosphere
Layer of gases that envelope the EarthLayer of gases that envelope the Earth
How big is the atmosphere?How big is the atmosphere?
Extends to 32,000 km (20,000 mi) from Extends to 32,000 km (20,000 mi) from surfacesurface
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 Layers of the of the AtmosAtmospherephere
Atmospheric TemperatureAtmospheric Temperature
TroposphereTroposphere– Surface to 18 km (11 mi)Surface to 18 km (11 mi)– 90% mass of atmosphere90% mass of atmosphere– Weather, most cloudsWeather, most clouds
Atmospheric TemperatureAtmospheric Temperature
TroposphereTroposphere– Normal environmental lapse rate – average Normal environmental lapse rate – average
cooling at rate of 6.4 C°/km (3.5 F°/1000 ft)cooling at rate of 6.4 C°/km (3.5 F°/1000 ft)– Environmental lapse rate – actual local lapse Environmental lapse rate – actual local lapse
raterate– Weather, most cloudsWeather, most clouds
Normal Environmental Lapse Rate in Normal Environmental Lapse Rate in TroposphereTroposphere
Atmospheric TemperatureAtmospheric Temperature
StratosphereStratosphere– 18 to 50 km (11 to 31 mi)18 to 50 km (11 to 31 mi)– Temperature risesTemperature rises– High, thin, ice crystal cloudsHigh, thin, ice crystal clouds– Ozone layerOzone layer
Atmospheric TemperatureAtmospheric Temperature
MesosphereMesosphere– 50 to 80 km (30 to 50 mi)50 to 80 km (30 to 50 mi)– Temperature fallsTemperature falls– Shooting “stars”Shooting “stars”
Atmospheric TemperatureAtmospheric Temperature
ThermosphereThermosphere– 80 km (50 mi) outward80 km (50 mi) outward– 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
Aerosols and ParticulatesAerosols and Particulates
Where do small particles of Where do small particles of liquid and solids come from?liquid and solids come from?
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