SOAR 2007SOAR 2007

Earth’s Atmosphere and WindEarth’s Atmosphere and Wind

Course OutlineCourse Outline Course Outline

Atmospheric structure, pressure & wind Oceanic Circulation Energy transfer & circulation Past Climates Global Climate Change

Course Outline Atmospheric structure, pressure & wind Oceanic Circulation Energy transfer & circulation Past Climates Global Climate Change

Origin of PlanetsOrigin of Planets Coalescence of matter in circumsolar

cloud Many Craters Collisions heat! Molten interior Interior layered Denser materials sink to center

Core mostly Iron (Fe) & Nickle (Ni) Crust mostly rocky (CaCO3, SiO2, etc)

Coalescence of matter in circumsolar cloud

Many Craters Collisions heat! Molten interior Interior layered Denser materials sink to center

Core mostly Iron (Fe) & Nickle (Ni) Crust mostly rocky (CaCO3, SiO2, etc)

Planetary AtmospheresPlanetary Atmospheres Form from

Gases from planet’s interior (volcanoes) Gases from impacts (planets)

Terrestrial Planets Mercury – none Venus CO2 with H2SO4 clouds

Mars – CO2 with H2O clouds

Earth – N2 with O2

Jupiter & Saturn – H with NH3 clouds Galilean moons – traces Titan – N2 with CH4

Uranus & Neptune – H with CH4 clouds

Form from Gases from planet’s interior (volcanoes) Gases from impacts (planets)

Terrestrial Planets Mercury – none Venus CO2 with H2SO4 clouds

Mars – CO2 with H2O clouds

Earth – N2 with O2

Jupiter & Saturn – H with NH3 clouds Galilean moons – traces Titan – N2 with CH4

Uranus & Neptune – H with CH4 clouds

Planetary AtmospheresPlanetary Atmospheres

Escape Velocity

Molecular Speed & Temp

or

Escape Velocity

Molecular Speed & Temp

or

center from

planetescape R

2GMv

NAME Mass RadiusWeight

of 150 lb person

Escape Speed

  (kg) (km) lb m/s1000 mph

SOL 2E+30 695990 4196 617439 1,381

MERCURY 3E+23 2440 57 4248 9.5

VENUS 5E+24 6052 136 10358 23

EARTH 6E+24 6378 150 11174 25

Luna 7E+22 1737 25 2376 5.3

MARS 6E+23 3397 57 5017 11

JUPITER 2E+27 71492 380 59524 133

Io 9E+22 1820 28 2557 5.7

Europa 5E+22 1570 20 2034 4.6

Ganymede 1E+23 2630 22 2749 6.1

Callisto 1E+23 2400 19 2450 5.5

SATURN 6E+26 60268 160 35473 79

Titan 1E+23 2670 19 2597 5.8

m

kTv

3

Constant sBoltzmann' 231038.1 KJk

kTmv2

3

2

1 2 avg

avg

Planetary AtmospheresPlanetary Atmospheres Presence & size due to combination of

Temperature = Distance from Sol Size of world = escape velocity

Large worlds Keep atmospheres even close to Sol

Small worlds Only have atmospheres far from Sol

Composition due to Size of world

Large worlds keep small molecules (H) Small worlds keep large molecules (N2, O2,

CO2)

Presence & size due to combination of Temperature = Distance from Sol Size of world = escape velocity

Large worlds Keep atmospheres even close to Sol

Small worlds Only have atmospheres far from Sol

Composition due to Size of world

Large worlds keep small molecules (H) Small worlds keep large molecules (N2, O2,

CO2)

kR3

2 molecule

world

worldEscape

mGMT

Inner PlanetsInner Planets Mercury

Small, hot no atmosphere stays Venus

Large, hot thick atmosphere NO WATER H2O H2 + O that binds with C, S, etc

CO2 + H2S04 Clouds Run-away greenhouse effect

Mars Small, cool thin atmosphere & thinning

Evidence of ancient oceans but water now present only as solid and gas

CO2 + H2O Clouds, fogs

Mercury Small, hot no atmosphere stays

Venus Large, hot thick atmosphere

NO WATER H2O H2 + O that binds with C, S, etc

CO2 + H2S04 Clouds Run-away greenhouse effect

Mars Small, cool thin atmosphere & thinning

Evidence of ancient oceans but water now present only as solid and gas

CO2 + H2O Clouds, fogs

Mars & VenusMars & Venus Both primarily CO2 but very different! Both primarily CO2 but very different!

Mars 95.3% CO2Mars 95.3% CO2

Venus 96.5% CO2Venus 96.5% CO2

250K – 273K = -23ºC = -10ºF

250K – 273K = -23ºC = -10ºF

750K – 273K = 477ºC = 890ºF

750K – 273K = 477ºC = 890ºF

Venus: Greenhouse gone wild!Venus: Greenhouse gone wild!

Interaction with SunlightInteraction with Sunlight Sky is blue because blue scatters, red

doesn’t Sky is blue because blue scatters, red

doesn’t

EarthEarth Complex atmospheric evolution

Primordial Atmosphere Lost to space H & He very light molecules, escape easily

Initially like Venus & Mars: mostly CO2

THEN Water condensed into oceans Oceans absorbed CO2

Locked it into rocks (CaCO3 = limestone)

Life flourished in oceans Released free oxygen

Sedimentary rocks turned red Ozone layer formed

Complex atmospheric evolution Primordial Atmosphere Lost to space

H & He very light molecules, escape easily

Initially like Venus & Mars: mostly CO2

THEN Water condensed into oceans Oceans absorbed CO2

Locked it into rocks (CaCO3 = limestone)

Life flourished in oceans Released free oxygen

Sedimentary rocks turned red Ozone layer formed

Evolution of Earth’s Atmosphere

Evolution of Earth’s Atmosphere

Oxygen content created,

maintained by life.

Oxygen content created,

maintained by life.

Atmospheric Structure

Atmospheric Structure

Layers (from surface) due to

Density (Pressure) Radiation Environment Temperature

Layers (from surface) due to

Density (Pressure) Radiation Environment Temperature

Atmospheric Structure

Atmospheric Structure

Layers (from surface)

Troposphere – sphere of weather

Stratosphere – sphere of ozone (O3)

Mesosphere Ionosphere – sphere of ions

Layers (from surface)

Troposphere – sphere of weather

Stratosphere – sphere of ozone (O3)

Mesosphere Ionosphere – sphere of ions

Atmospheric Structure

Atmospheric Structure

Layers By Function Ozonosphere (O3 layer)

Upper portion of Stratosphere

Absorbs UV (0.1-0.3 nm), radiates IR

Warmest layer in atmosphere

Harmed by CFC’s Cl + 2O3 Cl + 3O2

… and Cl is free to kill again!

Layers By Function Ozonosphere (O3 layer)

Upper portion of Stratosphere

Absorbs UV (0.1-0.3 nm), radiates IR

Warmest layer in atmosphere

Harmed by CFC’s Cl + 2O3 Cl + 3O2

… and Cl is free to kill again!

Ozone constantly created & destroyed by UV, CFC’s

increase destruction

Ozone constantly created & destroyed by UV, CFC’s

increase destruction

Hole in the ozone layer over AntarcticaHole in the ozone layer over Antarctica

Atmospheric StructureAtmospheric Structure Layers By Function

Ionosphere Thermosphere & Mesosphere Ionized particles (UV + atoms ions + e- +

energy Absorbs -rays, x-rays, UV, cosmic rays Reflects AM radio waves

Layers By Function Ionosphere

Thermosphere & Mesosphere Ionized particles (UV + atoms ions + e- +

energy Absorbs -rays, x-rays, UV, cosmic rays Reflects AM radio waves

Importance of WindImportance of Wind Arises due to differences in pressure

Distributes heat moisture dust pollutants microscopic life

Arises due to differences in pressure

Distributes heat moisture dust pollutants microscopic life

PaPaPascalPascalmetermeter

NewtonsNewtons

AreaAreaForceForce

PP 22

Air PressureAir Pressure Pressure is force/area = weight of air

column 1 in2 column

weight = 14.7 lb

1 m2 column weight = 10 tonnes

1 tonne = 1000 kg = 2204 lb

Why doesn’t the air pressure crush you when you lie down?

Pressure is force/area = weight of air

column 1 in2 column

weight = 14.7 lb

1 m2 column weight = 10 tonnes

1 tonne = 1000 kg = 2204 lb

Why doesn’t the air pressure crush you when you lie down?

Air PressureAir Pressure Standard Atmosphere

760 mm Hg 29.92 in Hg 33.9 ft. H2O 1013 millibars (mb) 1013 hPa hectopascals

Standard Atmosphere 760 mm Hg 29.92 in Hg 33.9 ft. H2O 1013 millibars (mb) 1013 hPa hectopascals

Weight of column of Hg

Weight of Hg = Weight of AirWeight of Hg = Weight of Air

Weight of column of air

Hg(tube area)(column height)

= (air presure)(bowl area)

Hg(tube area)(column height)

= (air presure)(bowl area)

Air PressureAir Pressure Varies with

altitude (in Pa, H in m)

air motion rising air = low pressure subsiding air = high

pressure moving air is at lower

pressure than still (or slower moving air … wind pulls curtains against window screen & airplane wings up!

Varies with altitude (in Pa, H in m)

air motion rising air = low pressure subsiding air = high

pressure moving air is at lower

pressure than still (or slower moving air … wind pulls curtains against window screen & airplane wings up!

155001550055loglog1010

HHPP

Air MotionAir Motion Updrafts – upward motion of air Downdrafts – downward motion of air Wind

Horizontal motion of air across Earth’s surface (advection)

Measured by anemometers 1 knot = 1 nautical mile/hour = (1 minute of latitude)/hour = 1.852 kph = 1.15 mph

Speed and Direction recorded

Updrafts – upward motion of air Downdrafts – downward motion of air Wind

Horizontal motion of air across Earth’s surface (advection)

Measured by anemometers 1 knot = 1 nautical mile/hour = (1 minute of latitude)/hour = 1.852 kph = 1.15 mph

Speed and Direction recorded

Driving ForcesDriving Forces Gravitational Force

Earth’s gravity holds atmosphere

Pressure Gradient force isobar = line of constant pressure Pressure Gradient force acts perpendicular

Gravitational Force Earth’s gravity holds atmosphere

Pressure Gradient force isobar = line of constant pressure Pressure Gradient force acts perpendicular

2

3moleculeworld

EscapeworldR k

mGMT

2

3moleculeworld

EscapeworldR k

mGMT

Importance of WindImportance of Wind

Only a difference in pressure

makes air move.

Only a difference in pressure

makes air move.

Driving ForcesDriving Forces Pressure

Gradient force Pressure

Gradient force

Indicated by density of

isobars

Indicated by density of

isobars

Driving ForcesDriving Forces Pressure

Gradient force Pressure

Gradient force

Indicated by density of

isobars

Indicated by density of

isobarsNorth America & Greenland, February 6, 18Z (1 pm EST)

18 hPa across ~400

km

Driving forcesDriving forces Pressure Gradient force

from high pressure to low pressure

Pressure Gradient force from high pressure to low pressure

Driving ForcesDriving Forces Coriolis Force

Acts ONLY ON MOVING objects proportional to velocity ( ) perpendicular to velocity acts over large distances

Does not determine direction water spins down a drain!

Coriolis Force Acts ONLY ON MOVING objects

proportional to velocity ( ) perpendicular to velocity acts over large distances

Does not determine direction water spins down a drain!

The rolling ball follows a straight path seen from above, a curved path seen from the rotating reference frame (riding on the merry-go-round).

The rolling ball follows a straight path seen from above, a curved path seen from the rotating reference frame (riding on the merry-go-round).

velocityvelocity

forceforcevvFF

Coriolis ForceCoriolis ForceDifferent latitudes

“orbit” axis at different

speeds.

Projectile carries small speed, falls

behind high speed equator.

Projectile carries small speed, falls

behind high speed equator.

Coriolis ForceCoriolis Force All moving objects are deflected

to their right in northern hemisphere to their left in southern hemisphere

All moving objects are deflected to their right in northern hemisphere to their left in southern hemisphere

Coriolis force deflects velocity no matter what

the original direction of the

velocity!

Coriolis force deflects velocity no matter what

the original direction of the

velocity!

Coriolis Force:Coriolis Force: All moving objects are deflected

All moving objects are deflected

to their right in

northern hemisphere

to their right in

northern hemisphere

to their left in southern hemisphere

to their left in southern hemisphere

Tropical Cyclone OlyviaTropical Cyclone Olyvia

Hurricane IsabelHurricane Isabel

Coriolis ForceCoriolis Force Northern

Hemisphere Moving objects

deflected to their own right.

Northern Hemisphere Moving objects

deflected to their own right.

Southern Hemisphere Moving objects

deflected to their own left.

Southern Hemisphere Moving objects

deflected to their own left.

L

Storms rotate counterclockwise

Storms rotate counterclockwise

L

Storms rotate clockwise

Storms rotate clockwise

Cyclones & AnticyclonesCyclones & Anticyclones Cyclone – circulation around low pressure

CCW in northern hemisphere CW in southern hemispere

Anticyclone – circ. around high pressure CW in northern hemisphere CCW in southern hemisphere

Cyclone – circulation around low pressure CCW in northern hemisphere CW in southern hemispere

Anticyclone – circ. around high pressure CW in northern hemisphere CCW in southern hemisphere

http://www.usatoday.com/weather/tg/whighlow/whighlow.htm

Driving ForcesDriving Forces Friction

Friction with ground slows wind Extends upward ~ 500 m Varies with surface, time

Friction Friction with ground slows wind Extends upward ~ 500 m Varies with surface, time

Friction with ground slows wind

Surface air slows air aloft

Geostrophic WindsGeostrophic Winds Pressure Gradient Force

creates wind ⊥ to isobars Coriolis Force

deflects motion to right in N. hemisphere

⇒ deflects Coriolis force!

Pressure Gradient Force creates wind ⊥ to isobars

Coriolis Force deflects motion to right in N.

hemisphere ⇒ deflects Coriolis force!

wind velocitywind velocity

Coriolis forceCoriolis force

Pressure Gradient force

Pressure Gradient force

IsobarsIsobarsForces

BalanceForces

Balance

wind along isobarwind along isobar

Wind deflects due to Coriolis force

Wind deflects due to Coriolis force

Coriolis force acts perpendicular to

new wind direction

Coriolis force acts perpendicular to

new wind direction

Geostrophic WindsGeostrophic Winds Pressure Gradient Force

creates wind ⊥ to isobars Coriolis Force

deflects motion to its right in N. hemisphere to its left in S. hemisphere

aligns wind with isobars

Pressure Gradient Force creates wind ⊥ to isobars

Coriolis Force deflects motion

to its right in N. hemisphere to its left in S. hemisphere

aligns wind with isobars

Surface Winds: Not GeostrophicSurface Winds: Not Geostrophic Friction slows winds at surface

Reduces Coriolis force Pressure Gradient force dominates

Friction slows winds at surface Reduces Coriolis force Pressure Gradient force dominates

Convection CellsConvection Cells

Sunlight heats land, water, air Land warms, heats air Air circulates

Convection cells warms -> expands -> rises cools -> contracts -> sinks

Water circulates Currents driven by wind & Earth rotation Water temperature increases SLOWLY

Large energy change needed for small temp. change

Sunlight heats land, water, air Land warms, heats air Air circulates

Convection cells warms -> expands -> rises cools -> contracts -> sinks

Water circulates Currents driven by wind & Earth rotation Water temperature increases SLOWLY

Large energy change needed for small temp. change

Convection CellsConvection Cells Hot surface heats air Air expands,

becomes less dense than surroundings rises, spreads out at top

Air aloft cools, becomes more dense than surroundings sinks, spreads out on surface

Hot surface heats air Air expands,

becomes less dense than surroundings rises, spreads out at top

Air aloft cools, becomes more dense than surroundings sinks, spreads out on surface

Atmospheric CirculatonAtmospheric Circulaton Rising Air

Cools Water vapor condenses (usually) results in clouds Lowers surface pressure

Rising Air Cools Water vapor condenses (usually) results in clouds Lowers surface pressure

Atmospheric CirculatonAtmospheric Circulaton Falling Air

Warms DRY (lost mosture rising) Increases surface pressure

Falling Air Warms DRY (lost mosture rising) Increases surface pressure

Atmospheric CirculationAtmospheric Circulation Sunlight heats ground Ground heats air , drives convection

from subsolar latitude

Sunlight heats ground Ground heats air , drives convection

from subsolar latitude

Maximum Insolation

Subsolar latitude is 23.5º

N/S on the solstices

Subsolar latitude is 23.5º

N/S on the solstices

Subsolar latitude is 0º on the equinoxes

Subsolar latitude is 0º on the equinoxes

Atmospheric Circulaton Atmospheric Circulaton

Air rises from

subsolar latitude,

clouds form &

precipitate, air aloft

moves N & S, cools,

dries & sinks at about 30º

N & S

Air rises from

subsolar latitude,

clouds form &

precipitate, air aloft

moves N & S, cools,

dries & sinks at about 30º

N & S

Moist air rising humid

Moist air rising humid

Dry air falling Arid

Dry air falling Arid

Air aloft cools until it sinks

Air aloft cools until it sinks

Air spreads N & S on surface

Air spreads N & S on surface

Driven by heating near equator

Driven by heating near equator

Atmospheric CirculatonAtmospheric Circulaton

Air from aloft sinks

near poles,

moves N & S along surface

Air from aloft sinks

near poles,

moves N & S along surface

Moist air rising humid

Moist air rising humid

Dry air falling Arid

Dry air falling Arid

Surface flows converge,

rise

Surface flows converge,

riseAir warms

and moistens along surface

Air warms and moistens along surface

Driven by cooling near

poles

Driven by cooling near

polesCold, dry air falling AridCold, dry air falling Arid

Moist air rising stormy

Moist air rising stormy

Moist air rising stormy

Moist air rising stormy

Dry air falling Arid

Dry air falling Arid

Dry air falling Arid

Dry air falling Arid

Pressure ZonesPressure Zones

Rising Air: Low

Pressure

Rising Air: Low

Pressure

InterTropical Convergence

Zone

InterTropical Convergence

Zone

Pressure ZonesPressure Zones

Falling Air: High

Pressure

Falling Air: High

Pressure

Pressure ZonesPressure Zones

Pressure

Zones: air motion is vertical so there is little wind!

Pressure

Zones: air motion is vertical so there is little wind!

Wind ZonesWind Zones

Winds: Falling air spreads North & South along

surface.

Winds: Falling air spreads North & South along

surface.

But the winds don’t go straight!But the winds don’t go straight!

Wind ZonesWind ZonesWinds named

for direction they are

from

Winds named

for direction they are

from

WesterliesWesterlies

WesterliesWesterlies

NE TradesNE Trades

SE TradesSE Trades

EasterliesEasterlies

EasterliesEasterlies

Doldrums

Horse Latitudes

Horse Latitudes

Polar Front

Polar Front

Windless zones names vary

Windless zones names vary

General Atmospheric Circulation

General Atmospheric Circulation

Cross sectional view Cross sectional view

ITCZITCZSTHPCSTHPCEasterly Trades

Easterly Trades

Polar HighPolar High

WesterliesWesterliesPolar Easterlies

Polar Easterlies

Dold

rum

sD

old

rum

s

Hors

e

Lati

tudes

Hors

e

Lati

tudes

Pola

r Fr

on

tPola

r Fr

on

t

World Pressure Cells: JanuaryWorld Pressure Cells: January

H

North American HighNorth American High

Parallel isobars over (low friction) ocean ⇒ rippin’ winds!!!

Parallel isobars over (low friction) ocean ⇒ rippin’ winds!!!

Aleutian Low

Aleutian Low

Islandic Low

Islandic Low

Siberian High

Siberian High

World Pressure Cells: JulyWorld Pressure Cells: July

Parallel isobars over (low friction) ocean ⇒ rippin’ winds!!!

Parallel isobars over (low friction) ocean ⇒ rippin’ winds!!!

Tibetan Low

Tibetan Low

Hurricane paths!Hurricane paths!

Azores High

Azores High

Monsoon Winds

Monsoon Winds

Upper Atmospheric WindsUpper Atmospheric Winds Jet Streams: Fast Winds Aloft

Polar Jet Stream Above Polar Front (midlatitude air meets polar) Rossby waves move loops north & south 7,600 – 10,700 m (25-35 kf) speeds up to 300 kph (190 mph)

Jet Streams: Fast Winds Aloft Polar Jet Stream

Above Polar Front (midlatitude air meets polar) Rossby waves move loops north & south 7,600 – 10,700 m (25-35 kf) speeds up to 300 kph (190 mph)

Upper Atmospheric WindsUpper Atmospheric Winds Jet Streams: Fast Winds Aloft

Subtropical Jet Stream above Subtropical highs (tropical air meets midlatitude)

9,100 – 13,700 m (30-35 thousand feet) speeds less than Polar Jet Stream

Jet Streams: Fast Winds Aloft Subtropical Jet Stream

above Subtropical highs (tropical air meets midlatitude)

9,100 – 13,700 m (30-35 thousand feet) speeds less than Polar Jet Stream

Polar Jet StreamPolar Jet Stream Determines N.Am. winter weather Strong west wind monitored by weather balloons

Determines N.Am. winter weather Strong west wind monitored by weather balloons

Check out PBS’s explanation!:

www.pbs.org/wgbh/nova/vanished/jetstream.html

Polar Jet StreamPolar Jet Stream Determines N.Am. winter weather Rossby waves bring cold air south

Determines N.Am. winter weather Rossby waves bring cold air south