Transcript Atmosphere Review

The Atmosphere
Bulletpoint Review for Exam
Atmosphere: Origin
 1st
atmosphere: Composed of H and He.
Eroded by solar winds and weak gravity.
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.
 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 Atmosphere

5 main layers of atmosphere w/
pseudolayer (ionosphere).

Pressure decreases exponentially w/ alt.

Temp changes vary w/ each specific layer
Troposphere
Closest to Earth (lowest alt.) 0~15km
 Clouds, wind, storms, and precipitation
occur in this layer. Tropopause traps H2O
 Highest pressure (101KPa, 760mmHg,
1Atm. @ sea level)
 Temperature  as alt. .

Stratosphere
 2nd
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.
Mesosphere
Located 50-80km alt.
 Temp. drops rapidly from 0 ˚C to -80 ˚C
(lowest temp. in atmosphere)

Thermosphere
Above mesosphere @ 80km-450km
 Main 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.

Ionosphere
Not 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.
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 Water
Water vapor resides in troposphere.
 Atm. water moved by water cycle.

Humidity
Def: 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.

Stratus
Stratus: lowest to ground layered and
sheetlike.
 Altostratus: higher alt. stratus.
 Nimbostratus: stratus clouds w/ rain.

Cumulus
Cumulus: next lowest to ground. Fluffy w/
flat bottoms (flat base marks dew point)
 Altocumulus: mid alt. cumulus.
 Cumulonimbus: large rain bearing cumulus

Cirrus
Cirrus: high alt. made of crystalized
droplets, have whispy appearance.
 Cirrostratus: high layered clouds form veil
over sky.

Air Pressure
Barometric 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.

Coriolis
Effects the north/south moving winds by
curving them east or west.
 Due to rotation of the planet @ diff.
velocities depending on latitude.

Weather and Climate
Air 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 Front
When 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 Front
Cold mass w/ steep edge lifts warm mass
up.
 Causes high wind, thunderstorms,
cumulonimbus clouds.

Lightning
Caused by charge buildup in atm. by
water droplets in clouds as they move.
 Spark discharges from ground to sky.

Thunder

Caused by rapid (faster than sound)
expansion of air heated by lightning bolt.

The shockwave of superheated air.
Tornadoes

Caused 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)
Tornados
Hurricanes
Caused 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.

Hurricane
Climate

Def: average weather patterns for a
region over many years.

Depends on latitude and variations in
topography of land.
Axis Tilt and the Seasons
Seasons 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 Seasons
Different 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 Axis
Climates over Time
Global climates are shifting periodically.
 Several factors cause climate shifts
including: continental drift, mountain
range formation, volcanism, and biological
activity.
