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!