Earths Atmosphere & Weather

Earths Atmosphere & Weather

Characteristics of the AtmosphereOrigin of Earths AtmosphereEarly Earth was HOT! Why? Accretion; Radioactive decay of elementsConsequences - Constant volcanism, surface temperature too high for liquid water or life as we know it, molten surface or thin, unstable basaltic crust. Cooling led to:Condensation & accumulation of surface water Changing atmosphere due to volcanic out-gassing The right conditions for the evolution of life

Source: http://www.ux1.eiu.edu/~cfjps/1400/atmos_origin.html1st AtmosphereComposition - H2, He Lost to space early in Earth's history because:Earth's gravity is not strong enough to hold lighter gases Earth still did not have a differentiated core (solid inner/liquid outer core) which creates Earth's magnetic field (magnetosphere = Van Allen Belt) which deflects solar winds. Once the core differentiated the heavier gases could be retained

2nd AtmosphereProduced by volcanic out-gassing. H2O, CO2, SO2, CO, S2, Cl2, N2, H2 and NH3 (ammonia) and CH4 (methane) No free O2 at this timeOcean Formation - As the Earth cooled, H2O produced by out-gassing could exist as liquid in the early Archean, allowing oceans to form.

Addition of O2Photochemical dissociation - breakup of water molecules by UV radiationProduced O2 levels approx. 1-2% current levels At these levels O3 (Ozone) can form to shield Earth surface from UV Photosynthesis CO2 + H2O + sunlight glucose + O2 O2 produced by cyanobacteria, and eventually higher plants

Present Composition78% Nitrogen21% Oxygen1% Other trace gasesLayers of the AtmosphereCaused by temp. differencesThese differences result from how solar energy is absorbed as it moves through the atmosphere

http://www.aerospaceweb.org/question/atmosphere/atmosphere/layers.gif4 Main Layers of the Atmosphere

http://www.epa.gov/apti/course422/images/fig-1.gif

http://www.greenfacts.org/images/glossary/stratosphere-troposphere.jpg

TroposphereClosest to EarthNearly all weather occurs hereAlmost all H2O vapor and CO2Temp. decreases with altitude because air in this layer is heated from below by thermal energy that is re-radiated from Earths surface

TropopauseUpper boundary of the troposphereJet streamVaries with latitude & seasons250 mphEast wind

Stratosphere16 50 kmOzone layer is hereTemp. increases because air is heated from above by absorption of solar radiation by ozoneJets fly here to avoid turbulenceStratopause - upper boundary

Ozone LayerOzone is made of 3 atoms of oxygen (O3) 2-3 mm thick if it were at sea levelPurpose - absorbs harmful UV radiation from the Sun

Mesosphere50 85 kmTemp. decreases as altitude increases Mesopause - Upper boundaryAvg Temp. = - 90oCCOLDEST layer in the atmosphereMeteors begin to disintegrate here

Red SpriteBurning Tree Sprite Credit: ISUAL Project, NCKU / NSPO, Taiwan Explanation: This dramatic, garishly colored image was captured with a low-light level camera on 2001 June 7. It shows what appears to be a "burning tree" above the National Cheng Kung University campus in Tainan City, Taiwan ... but the burning tree is actually a fleeting red sprite 300 kilometers away. Red sprites are recently discovered and still poorly understood optical flashes seen dancing at altitudes of 30 to 90 kilometers above thunderstorms. Cousins to lightning bolts, red sprites occur near the edge of the atmosphere and have been glimpsed by astronauts from orbit. What ever their cause, the red sprite flashes usually last only tenths to hundredths of a second and characteristically take on shapes which researchers describe as columns, fingers, trees, or carrots.

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SpritesSprite Fireworks Credit: D. Sentman (U. Alaska) et al., EXL98 Campaign, AFRL, NRL, USAFA, NASA Explanation: Sometimes lightning occurs out near space. One such lightning type is the recently documented red sprite lightning, which has only been photographed and studied on Earth over the last few years. The origins of all types of lightning remains unknown, and scientists are even trying to figure out why red sprite lightning occurs at all. What is known is that as some large, positive cloud-to-ground lightning strokes occur, millisecond flashes appearing red may also occur far above in the upper atmosphere. Pictured above, a group of red sprites was photographed at high resolution. Reasons for the observed complexities are being researched.

20Sprites

Red Sprite Lightning Credit: D. Sentman, G. Wescott, Geophysical Institute, U. Alaska Fairbanks, NASA Explanation: Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning. Red sprites appear red in color and go from the tops of clouds to as high as the ionosphere - an ionized layer 90 kilometers above the Earth's surface. They last only a small fraction of a second. The existence of red sprites has been suggested previously, but only in 1994 were aircraft flown above massive thunderstorms with the high speed video equipment necessary to verify these spectacular events. Scientists are unsure of the cause and nature of red sprites. 21Blue Jets

Blue Jet Lightning Credit: D. Sentman, G. Wescott, Geophysical Institute, U. Alaska Fairbanks, NASA Explanation: Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning. Blue jets appear blue in color and go from the tops of clouds to a height of about 50 kilometers. Because blue jets typically last almost a full second, one can easily see the jet rise from the clouds with a fast video camera. Blue jets appear as narrow cones and travel about 100 kilometers per second. The existence of blue jets has been suggested previously, but only in 1994 were aircraft flown above massive thunderstorms with the high speed video equipment necessary to verify these spectacular events. The above black & white picture shows several blue jets rising from a thunderstorm simultaneously. Part of the aircraft is visible in silhouette on the right. Scientists are unsure of the cause and nature of blue jets. 22E.L.Ves.Emission of Light and Very low frequency perturbations

Thermosphere90 km ~ 1000 kmSpace begins here (~100 km)Temp. increases as altitude increasesCant read temp. with a thermometer because air particles are too far apartSpace Shuttle & ISS orbit hereIonosphere is the lower regionAurora occur here

ExosphereEnd of the atmosphereAlmost a vacuumWhere light elements escape Earths gravity

http://curriculum.calstatela.edu/courses/builders/lessons/less/les3/les3gifs/layers.gifThe Water Cycle

Temperature & Humidity

TemperatureA measure of the kinetic energy of the molecules of a substance

Methods of Heat TransferConduction direct transferConvection bulk movement of particlesRadiation electromagnetic waves

Where does radiation go?25% penetrates Earths atmosphere20% absorbed by the atmosphere30% scattered back into space (albedo)

AlbedoVaries due to Cloud coverParticulate matter (dust, pollen, ash, etc.)Suns angleSurface (water vs. land)

Differential HeatingEarths surface is heated unevenly due to:

Geographic position (latitude)Land vs. WaterAltitudeOcean currentsCloud coverAlbedo

HumidityThe amount of water vapor in the air90% of water vapor comes from oceans (evaporation)The warmer air is, the more water vapor it can hold

Dew PointThe temp. at which water vapor begins to condenseIf the dew point and air temp. are the same, the following will form:At ground level = dew or frostJust above ground = fogHigher levels = clouds

Relative HumidityThe amount of water vapor in the air expressed as a percentage of the amount required to saturate the air at the current temp.

% R.H. = Actual absolute humidity x 100Maximum absolute humidity

PsychrometerUsed to measure humidityMade with 2 thermometersDry bulbMeasures air temp.Wet bulbCooler than dry bulbUses evaporation to measure temp.Wet bulb depression difference between dry & wet bulb temps.

Pollution &Its Effects On the AtmosphereParticulatesTiny, solid particlesVolcanic dustAsh f/ firesMicroscopic organismsMineral particles f/ the soilPollen f/ plantsParticles f/ meteorsSalt f/ the oceanCan be suspended for mos or yrsFly ash from burning wastes

http://images.google.com/imgres?imgurl=http://www.chemsoc.org/exemplarchem/entries/2002/Air%2520pollution%2520-%2520Smith%2520%26%2520Kirsop/particulates.gif&imgrefurl=http://www.chemsoc.org/exemplarchem/entries/2002/Air%2520pollution%2520-%2520Smith%2520%26%2520Kirsop/dogs16.htm&h=251&w=332&sz=62&hl=en&start=1&tbnid=jq-gUdKJKpbV4M:&tbnh=90&tbnw=119&prev=/images%3Fq%3Dparticulates%26svnum%3D10%26hl%3Den%26rls%3DTSHA,TSHA:2006-08,TSHA:enAir PollutantsAny substance that is in the atmosphere & is harmful to people, animals, plants or propertyMain source is burning of fossil fuelsThese release harmful substances SO2, hydrocarbons, N oxides, CO & Pb into the airPollutants

http://www.greenfacts.org/images/glossary/secondary-pollutants.jpg

http://www.nuigalway.ie/ccaps/research_atmospheric_composition.html

http://www.windows2universe.org/earth/Atmosphere/ozone_hole.htmlBreaking Down the Ozone LayerCFCs (chlorofluorocarbons) break down the ozone layerThey used to be used in refrigerators, air conditioners & exhaust compounds

www.theozonehole.com

www.theozonehole.com

Temperature InversionsWhen a layer of warm air is on top of cool airThis can trap polluted air beneathTopography can make it worseSmog occurs b/c of the pollutants & lack of circulation

Temperature Inversion

http://www.epa.qld.gov.au/images/environmental_management/air/warm_air_inversion.jpg

http://www.virtual-lakes.co.uk/DerLatriggInversion.jpg

http://www.weatherquestions.com/temperature_inversion.jpgHow to Control SmogPrevent the release of pollutantsPassage of lawsCommunity awarenessPersonal responsibility

http://davidk.scelerat.com/images/smog-med.jpg

Atlanta, GAhttp://gallery.bostonradio.org/2004-11/atlanta/100-02527-med.jpg