The AtmosphereThe AtmosphereBulletpoint Review for Exam

Atmosphere: OriginAtmosphere: Origin1st atmosphere: Composed of H

and He. Eroded by solar winds and weak gravity.

Origin Cont.Origin Cont.2nd atmosphere: Composed of gases

released by volcanoes (outgassing). Included all components of current atmosphere except O2 .

Oceans formed from water vapor cooling/condensing.

Origin Fin.Origin Fin.3rd atmosphere: O2 released into

air by splitting of H2O (ozone layer forming @ this time) and primarily by photosynthesis from cyanobacteria. Current O2 at 360 million years ago.

Layers of AtmosphereLayers of Atmosphere5 main layers of atmosphere w/

pseudolayer (ionosphere).

Pressure decreases exponentially w/ alt.

Temp changes vary w/ each specific layer

TroposphereTroposphereClosest to Earth (lowest alt.)

0~15kmClouds, wind, storms, and

precipitation occur in this layer. Tropopause traps H2O

Highest pressure (101KPa, 760mmHg, 1Atm. @ sea level)

Temperature as alt. .

StratosphereStratosphere2nd from ground (15-45km)Ozone layer here.Temp. increases due to O3

molecules absorbing UV rays. From -55˚C to 0 ˚C

Ozone layer shields surface from UV.

MesosphereMesosphereLocated 50-80km alt.Temp. drops rapidly from 0 ˚C to

-80 ˚C (lowest temp. in atmosphere)

ThermosphereThermosphereAbove mesosphere @ 80km-

450kmMain gases are still N2 and O2 but

molecules are up to a kilometer apart (pressure close to vacuum).

Temperature rapidly due to O2 molecules absorbing intense solar radiation.

Temp. climbs to about 980 ˚C.

IonosphereIonosphereNot a layer by location like others,

but rather a location where atm. Gas mol. are ionized by solar radiation.

Radiowaves reflect off e- and allow long range radio comm.

Radios work better @ night since waves travel further into atm. before reflecting.

Organisms and Atm.Organisms and Atm.Plants release O2 into atm. And

animals release CO2. Humans release CFC’s which destroy

O3 mol. and deplete ozone layer.Excess carbon dioxide release by

burning fossil fuels (petroleum, coal, etc.) causes greenhouse effect, trapping solar rays.

Global warming occurs when avg. temp. increase globally.

Wind and WaterWind and WaterWater vapor resides in

troposphere.Atm. water moved by water

cycle.

HumidityHumidityDef: the amount of water in air.Measured by relative hum. which

is amount water/total amount possible

Warm air holds more water since gas mol. further apart, more water mol. can fit.

Dew Point: temp @ which rate condensation and evap. are same.

StratusStratusStratus: lowest to ground layered

and sheetlike.Altostratus: higher alt. stratus.Nimbostratus: stratus clouds w/

rain.

CumulusCumulusCumulus: next lowest to ground.

Fluffy w/ flat bottoms (flat base marks dew point)

Altocumulus: mid alt. cumulus.Cumulonimbus: large rain

bearing cumulus

CirrusCirrusCirrus: high alt. made of

crystalized droplets, have whispy appearance.

Cirrostratus: high layered clouds form veil over sky.

Air PressureAir PressureBarometric pressure/air

pressure/atm. Pressure: the pressure resulting from the weight of air column extending to thermosphere.

Barometer: measures air pressure using mercury pool with a column.

Diff. in pressure cause air to move = Wind.

CoriolisCoriolisEffects the north/south moving

winds by curving them east or west.

Due to rotation of the planet @ diff. velocities depending on latitude.

Weather and ClimateWeather and ClimateAir masses differ in relative

temp.When masses of diff. temp. meet

that is called a front.3 types of front: warm, cold, and

stationary.

Warm FrontWarm FrontWhen warm air mass meets cold

mass.Warm mass slides over top of

cold. This causes cooling, condensing, and precipitation from warm mass.

Preceded by cirrus altostratus and nimbostratus clouds

Cold FrontCold FrontCold mass w/ steep edge lifts

warm mass up.Causes high wind,

thunderstorms, cumulonimbus clouds.

LightningLightningCaused by charge buildup in atm.

by water droplets in clouds as they move.

Spark discharges from ground to sky.

ThunderThunderCaused by rapid (faster than

sound) expansion of air heated by lightning bolt.

The shockwave of superheated air.

TornadoesTornadoesCaused by wind shear b/n cold

dry mass and warm moist mass.

Rotating winds spiraling in opposite directions form upward vortex with highest winds in atm. (500km/hr)

TornadosTornados

HurricanesHurricanesCaused by tropical depressions

where low pressure gen. by warm water evap. and heating air.

Causes a self feeding system until sufficient strength to form hurricane.

Very large with wind speeds of up to 250km/hr.

HurricaneHurricane

ClimateClimateDef: average weather patterns

for a region over many years.

Depends on latitude and variations in topography of land.

Axis Tilt and the SeasonsAxis Tilt and the SeasonsSeasons caused by differences in

amount of direct sunlight due to axis tilt as Earth revolves around sun.

Not dependant on distance to sun. Depends on concentration of solar rays.

Warmer at equator (almost always direct)

Cold at poles (almost always indirect)

Topography and SeasonsTopography and SeasonsDifferent land formations can

affect climate.Mountains force air to increase

alt. causing them to cool, condense, and precipitation. Rainy moist climates leeward.

Rain shadow of mountains due to drier air descending and warming tends to cause desert climates.

Seasons and AxisSeasons and Axis

Climates over TimeClimates over TimeGlobal climates are shifting

periodically.Several factors cause climate

shifts including: continental drift, mountain range formation, volcanism, and biological activity.