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22.1 Introduction to the 22.1 Introduction to the AtmosphereAtmosphere
(Layers & composition)(Layers & composition)
By Unknown Author & Bill Holmes, U. of MichiganModified by Laura Smith
Thin Thin Blue Line Line
Click on picture or title
The The layers of gaslayers of gas surrounding the Earth surrounding the Earth MixtureMixture of chemicals (elements and compounds) of chemicals (elements and compounds)
called AIRcalled AIR
ProtectsProtects Earth from Earth from solar radiationsolar radiation Helps Helps regulate temperatureregulate temperature on the planet on the planet Divided into Divided into layerslayers based on based on temperaturetemperature changes changes
with increasing altitudewith increasing altitude
The AtmosphereThe Atmosphere
Composition of the AtmosphereComposition of the Atmosphere
Composition of the AtmosphereComposition of the Atmosphere
Argon,
Which Gas Makes Up More of Which Gas Makes Up More of Our Atmosphere: Our Atmosphere:
NitrogenNitrogen oror OxygenOxygen??
This question will try to trick you in This question will try to trick you in the future!the future!
NITROGENNITROGEN
Nitrogen makes up about 78% of Nitrogen makes up about 78% of EarthEarth’’s atmosphere and is maintained s atmosphere and is maintained through the through the nitrogen cycle.nitrogen cycle.
NITROGENNITROGEN Nitrogen is removed from the air mainly Nitrogen is removed from the air mainly
by the action of nitrogen-fixing by the action of nitrogen-fixing bacteriabacteria..
DecayDecay releases nitrogen back into the releases nitrogen back into the atmosphere.atmosphere.
OXYGENOXYGEN
Oxygen makes up about Oxygen makes up about 21% of 21% of EarthEarth’’s s atmosphereatmosphere..
Land and ocean plants produce large Land and ocean plants produce large quantities ofquantities of oxygen oxygen in a process called in a process called photosynthesisphotosynthesis..
Stromatolites
Cyanobacteria
OXYGENOXYGEN
Bacteria and plants Bacteria and plants add oxygenadd oxygen from from the air as part of their life processes.the air as part of their life processes.
Animals Animals removeremove oxygenoxygen from the air. from the air.
WATER VAPORWATER VAPOR
As water evaporates from oceans, lakes, As water evaporates from oceans, lakes, streams, and soil, it enters air as the streams, and soil, it enters air as the invisible gas invisible gas water vaporwater vapor..
Plants give off water vapor during Plants give off water vapor during transpiration; transpiration; animals during animals during respirationrespiration..
WATER VAPORWATER VAPORAs water vapor enters the atmosphere, it As water vapor enters the atmosphere, it is removed by the processes of is removed by the processes of condensation condensation and and precipitation precipitation in thein the hydrologic, hydrologic, oror water cycle water cycle..
WATER VAPORWATER VAPOR
The The humidityhumidity is a measure of the water is a measure of the water vapor in the air.vapor in the air.
The The percentagepercentage of water vapor in the of water vapor in the atmosphere atmosphere variesvaries depends on factors depends on factors such as such as time of day, location, and time of day, location, and season.season.
WATER VAPORWATER VAPOR
Relative Relative humidity changes with humidity changes with temperature.temperature.
OZONEOZONE
OzoneOzone is is a gas a gas molecule that is made molecule that is made up of up of three oxygenthree oxygen atomsatoms
Ozone in the upper Ozone in the upper stratosphere forms the stratosphere forms the ozone layerozone layer, which , which absorbs harmful absorbs harmful ultraviolet radiationultraviolet radiation from the sun.from the sun.
OZONEOZONE Ozone in the upper stratosphere forms the Ozone in the upper stratosphere forms the
ozone layerozone layer, which absorbs much of the , which absorbs much of the harmful harmful ultraviolet radiationultraviolet radiation from the sun. from the sun.
OZONEOZONE
Without the ozone Without the ozone layer, living layer, living organisms would organisms would be severely be severely damaged damaged by the by the sunsun’’s ultraviolet s ultraviolet rays.rays.
OZONEOZONE Unfortunately, a number Unfortunately, a number
of human activities of human activities damagedamage the ozone layer. the ozone layer.
CChlorohloroFFluoroluoroCCarbons arbons (CFCs) (originally used (CFCs) (originally used in aerosols & refrigerants in aerosols & refrigerants & styrofoam & styrofoam manufacturing) break manufacturing) break apart ozone molecules apart ozone molecules creating a creating a ““holehole”” in the in the ozone layerozone layer
Too much here... Vehicles, power plants and factories emit air pollution that forms ground-level ozone.
Too little there... CFC’s and halons from air conditioners and refrigerators break down the protective ozone layer.
Good Ozone, Bad OzoneGood Ozone, Bad Ozone
Sources of Ground-Level OzoneSources of Ground-Level Ozone
NOx, VOC + sunlight
Ozone
OZONE HOLEOZONE HOLE
NASA Exploring OzoneClick title for 2:20 min video
OZONE HOLEOZONE HOLE OZONE HOLE 1979-2007 MOVIE
OZONE HOLEOZONE HOLE
Ozone Movie
PARTICULATESPARTICULATES Many Many naturalnatural and and manmademanmade particulates are particulates are
in the atmospherein the atmosphere DustDust, , pollenpollen, , volcanicvolcanic eruptions and eruptions and seasea
spray all add natural, tiny solid particles to spray all add natural, tiny solid particles to the atmosphere.the atmosphere.
Man-made particulates = pollutionMan-made particulates = pollution
Primary PollutantsPrimary Pollutants
Atmospheric PressureAtmospheric PressureAtmospheric PressureAtmospheric Pressure the the forceforce per unit per unit areaarea
that is exerted on a that is exerted on a surfacesurface by the by the weightweight of of the atmospherethe atmosphere
Atmospheric PressureAtmospheric Pressure Gravity Gravity holds the gases of the holds the gases of the
atmosphere near Earthatmosphere near Earth’’s surface. s surface. As a result, the air molecules are As a result, the air molecules are
compressedcompressed together and exert together and exert forceforce on on EarthEarth’’s surface.s surface.
Atmospheric PressureAtmospheric Pressure
Atmospheric Pressure is measured with a Atmospheric Pressure is measured with a barometer.barometer.
Atmospheric PressureAtmospheric Pressure
Atmospheric PressureAtmospheric Pressure Atmospheric pressure is exerted Atmospheric pressure is exerted equallyequally
in all in all directionsdirections—up, down, and —up, down, and sideways-- and results from sideways-- and results from collisioncollision of of gas particles.gas particles.
Atmospheric PressureAtmospheric Pressure
At higher altitudes, or elevations, air molecules are farther apart and exert less pressure on each other (and you).
Layers of the AtmosphereLayers of the AtmosphereTroposphere:Troposphere:((““changechange””)) Lowest layer Lowest layer
(0-18 km = 0-10 miles)(0-18 km = 0-10 miles) WarmestWarmest layer; decreases layer; decreases
going up (20° at bottom to -60° at going up (20° at bottom to -60° at top)top)
Weather occurs here; clouds Weather occurs here; clouds form at topform at top
Water vapor & CO2Water vapor & CO2 All LifeAll Life Hot Air Balloons, airplanes, birdsHot Air Balloons, airplanes, birds Densest & smallest layerDensest & smallest layer
Layers of the AtmosphereLayers of the AtmosphereStratosphere: (Stratosphere: (““LayerLayer””)) Second layer (18-50 km = Second layer (18-50 km =
28-31 miles)28-31 miles) Ozone layer (@20-30km) Ozone layer (@20-30km)
blocks UV raysblocks UV rays Temp. goes up as you go Temp. goes up as you go
up (-60° bottom to 0° at up (-60° bottom to 0° at top)top)
Windy & DryWindy & Dry Weather balloonsWeather balloons Some jet planes and Some jet planes and
clouds at bottomclouds at bottom
Layers of the AtmosphereLayers of the Atmosphere
Mesosphere: Mesosphere: ((““middlemiddle””))
Third layer Third layer (50 - 80 km= 53-62 (50 - 80 km= 53-62 miles)miles)
Meteors burn upMeteors burn up ColdestColdest layer (0° layer (0°
at bottom to -80°C at bottom to -80°C at top)at top)
Layers of the AtmosphereLayers of the AtmosphereOuter Space (‘Exosphere’)
Ionosphere:Ionosphere: At Mesopause & in At Mesopause & in
both Meso- & Thermo- both Meso- & Thermo- spheresspheres
96-112+ km 96-112+ km Solar energy removes Solar energy removes
electronselectrons Four layers of ions Four layers of ions
and electronsand electrons Causes Aurora Causes Aurora
Borealis&AustralisBorealis&Australis Bounces radio waves Bounces radio waves
(esp. AM)(esp. AM)
IONOSPHERE
Layers of the AtmosphereLayers of the AtmosphereThermosphere:Thermosphere:
((““HeatHeat””)) Highest layer (80 Highest layer (80
~ 500 km = 82-~ 500 km = 82-~373 mi)~373 mi)
K.E. of particles K.E. of particles equal to 2000°C! equal to 2000°C!
Aurorae Aurorae Satellites and Satellites and
Space StationsSpace Stations
Outer Space (‘Exosphere’)
Layers of the AtmosphereLayers of the Atmosphere
““PAUSESPAUSES”” Breaks between layersBreaks between layers Delineated by changes Delineated by changes
in temperature in temperature direction (starts rising direction (starts rising or falling here)or falling here)
All layers and pause All layers and pause heights vary based on heights vary based on latitude and seasonlatitude and season
TROPOPAUSE
STRATOPAUSE
MESOPAUSE
THERMOPAUSE
Layers of the AtmosphereLayers of the AtmosphereOuter Space (‘Exosphere’)Exosphere: (Exosphere: (““EXITEXIT””))
Highest layer Highest layer (Above ~ (Above ~ 500 km)500 km)
Some consider this Some consider this outside the outside the atmosphereatmosphere
Blends with the Blends with the complete vacuum of complete vacuum of space (No limit)space (No limit)
Temperature drops Temperature drops againagain
How the Temperature Changes in How the Temperature Changes in the Layersthe Layers
Temperature Temperature trends trends alternatealternate from layer to from layer to layerlayer
These shifts are These shifts are the the boundariesboundaries between layersbetween layers
Memorize theseMemorize these! !
Silly way to remember the order Silly way to remember the order of the layersof the layers
EE xtra xtra
TT errestrials errestrials
MM ay ay
SS wim wim
TTonightonight
Temperature InversionsTemperature Inversions Warm air risesWarm air rises Cold air sinksCold air sinks Cool air during the Cool air during the
winter, or from winter, or from ocean influences, ocean influences, gets trapped gets trapped beneath warmer air beneath warmer air passing over passing over mountains = mountains = temperature temperature inversionsinversions
Temperature InversionsTemperature Inversions
Salt Lake City, UT
Denver, CO
Los Angeles, CA
What Was the Early Atmosphere What Was the Early Atmosphere Like?Like?
4.4 billion years ago:4.4 billion years ago:
– Formed by Formed by volcanic eruptionsvolcanic eruptions and and meteorite meteorite impactsimpacts
– Mostly Mostly carbon carbon dioxidedioxide, water , water vapor, and some vapor, and some nitrogennitrogen
– No known lifeNo known lifehttp://news.nationalgeographic.com/news/2011/09/110907-gold-metals-earth-meteors-oldest-rocks-nature-science/
A bright Geminid meteor pierces the night sky over California's Mojave Desert in 2009.
Plants Changed the AtmospherePlants Changed the Atmosphere Tiny marine Tiny marine plantsplants
(cyanobacteria, (cyanobacteria, phytoplankton, and algae) phytoplankton, and algae) appear:appear:
– PhotosynthesizePhotosynthesize carbon carbon dioxide to oxygendioxide to oxygen
– Over millions of years: Over millions of years: carbon dioxide falls and carbon dioxide falls and oxygen risesoxygen rises
Evidence?Evidence?
1.1. FossilsFossils- - Plants need carbon Plants need carbon dioxidedioxide and and animals animals need oxygenneed oxygen
- - Earliest fossils = plants Earliest fossils = plants onlyonly
(so there was carbon (so there was carbon dioxide)dioxide)
Animal fossils later appear in rocksAnimal fossils later appear in rocks (so oxygen (so oxygen was in the air at that time) was in the air at that time)
More evidenceMore evidence2.2. Glacial Ice CoresGlacial Ice Cores
- Some glaciers (frozen rivers of ice) have - Some glaciers (frozen rivers of ice) have existed for millions of years.existed for millions of years.- When the glacier freezes, it - When the glacier freezes, it traps bubbles of traps bubbles of the current atmospherethe current atmosphere..
We can sample the glaciers (ice cores) and measure We can sample the glaciers (ice cores) and measure the abundance of gases trapped inside.the abundance of gases trapped inside.
Ice cores show us that:Ice cores show us that:
Oldest ice contains no oxygen, but plenty of Oldest ice contains no oxygen, but plenty of carbon dioxide and nitrogencarbon dioxide and nitrogen
As ice gets younger, the carbon dioxide falls As ice gets younger, the carbon dioxide falls and oxygen risesand oxygen rises
Is EarthIs Earth’’s Atmosphere Unique?s Atmosphere Unique?
It has huge It has huge amounts of water amounts of water vapor vapor
The temperature is The temperature is just right just right
Contains huge Contains huge amounts of oxygenamounts of oxygen
Yes, and thank goodness!
They’re out of this world!!!!They’re out of this world!!!!
Extra Terrestrial AtmospheresExtra Terrestrial Atmospheres
http://www.grida.no/publications/vg/climate/page/3056.aspx
LetLet’’s look at our neighbors:s look at our neighbors:
The Atmosphere on The Atmosphere on MarsMars Thin, dustyThin, dusty Low pressureLow pressure 95% carbon dioxide, 95% carbon dioxide,
3% nitrogen, 3% nitrogen,
1.6% argon, and only 1.6% argon, and only traces of oxygen, traces of oxygen, water, and methanewater, and methane
Carbon dioxide Carbon dioxide icecaps at the poles icecaps at the poles
And now, EarthAnd now, Earth’’s Twin…..s Twin…..
The Atmosphere on VenusThe Atmosphere on Venus
Thick, dryThick, dry Almost entirely carbon Almost entirely carbon
dioxide and nitrogendioxide and nitrogen Thick clouds of sulfur Thick clouds of sulfur
dioxide that rain aciddioxide that rain acid GREENHOUSE GREENHOUSE
EFFECT (460EFFECT (460º C)º C)
Could Venus foretell our future?Could Venus foretell our future?
Scientists think that the hostile environment Scientists think that the hostile environment on Venus used to be more like Earthon Venus used to be more like Earth
There may have been lots of liquid water on There may have been lots of liquid water on VenusVenus’’s surfaces surface
The water was evaporated away by the The water was evaporated away by the greenhouse effectgreenhouse effect
It’s all we have! It’s all we have! Protect it!Protect it!
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