Chapter 7: The Ocean and Atmosphere

• Objectives:• Structure/composition of air

• Sulfur compounds

• General circulation patterns

• Coriolis Effect

• Seasonal Changes

• El Nino, La Nina

• Storms

• Practical Considerations

Ocean and Atmosphere

• Can’t separate; closely related:

• Moderates surface temperature

• Shapes weather and climate

• Creates most of sea’s waves and currents

Structure and Composition• 90% of gases = within 9 mi. from surface

• Troposphere temp. from conduction

• Greenhouse Effect; Global Warming

• Stratosphere: Ozone; depletion

• Mesosphere: colder

• Thermosphere: leads to outer space

• 78% N, 21% O in dry air

• Weather =

• Climate =

• Influenced by:

Solar radiation

Land

Nearby body of water

Changing geo and bio conditions

Measuring Earthshine How much radiation the Earth reflects.

GREENHOUSE EFFECT• Gases: CO2, CH4, H2O, CFC, N2O

• Trend: increase in gases global warming of 2-4 degrees C in next 100 yrs.

• **Unbalances C cycle• Possible sea-surface effects:

– Affects high latitudes melt polar icecaps

– Affects thermohaline circulation and surface winds modify transfer of heat from low to high latitudes alters Earth’s climate patterns

OZONE DEPLETION• Monitored since 1978• CFC’s (1 molecule breaks down 100,000 molecules of

ozone)• Methyl bromide: from single celled algae at surface,

pesticides, industry, burning of vegetation.• Problems:• Pollutant at ground level• Skin cancer, cataracts• Sunburns, earlier wrinkles• Suppress immune systems crop production• Degradation of paint, plastics in phytoplankton productivity

Ozone Depletion

Sulfur Compounds• 20-40 million T from dimethyl sulfide

(DMS) from phytoplankton at surface (odor of sea)

• DMS sulfate & water sulfuric acid acid rain

• Controls density of clouds over sea

• DMS changes reflective prop., reduces incoming radiation, heating of ocean surface

DMS, excess clouds + sulfur over sea less light hitting surface, temp , plant production of DMS

SELF REGULATING

ATMOSPHERIC CIRCULATION• Uneven solar heating wind

• Convection current

• Patterns if world was still

• CORIOLIS EFFECT: apparent deflection of a moving object from its initial course when its speed and direction = measured in reference to the surface of the rotating Earth.

• Earth moves 15 degrees/hour

• All places on Earth don’t move at same speed

• N. Hemisphere winds = clockwise

• S. Hemisphere counterclockwise

• Equator none

• Coriolis Effect only influences wind

Wind Bands• Geographical Equator = 0o

• Meteorological Equator = ITCZ, ~5o N or S of Equator

*Maintains thermal equilibrium

• 3 convection cells of air:

1. 0o--30o

2. 30o--60o

3. 60o--90o

Wind Patterns1. Trade winds: bands of moving air

between 0--30

movement to right (west)

steady speed, direction

2. Westerlies: between 30--60

go to east

Winds = named for direction of origin

3. Horse Latitudes: 30 degrees N and S

air = dry, deserts

4. Doldrums: at Equator

low a.p., moist air, rainforests

vertical movement of air

5. Polar Easterlies: betw. 60 degrees and

and the Poles

6 surface wind bands

Measuring winds: surface, satellites

• Cell circulation: depends on

1. Seasonal changes

2. Amount of land

3. Amount of ocean

**Remember: land doesn’t have the high heat capacity of water --> temperature fluctuations = greater.

Seabreeze

Landbreeze

MONSOONS• Pattern of wind circulation that changes

with seasons due to heat capacities of land and water and moving ITCZ.

• Wet summers, dry winters

• In spring: land heats more rapidly than ocean, air over land rises and cool moist air rushes in to take its place --> rain

• In winter: opposite. Dry surface winds move seaward.

Delhi Floods

Air Masses• Large body of air with nearly same temp,

humidity, and density throughout

• characteristics come from where they were formed

• mT (maritime tropical) = warm, moist

• mP (maritime polar) = cold, moist

• cT (continental tropical) = warm, dry

• cP (continental polar) = cold, dry

• cold front, warm front, stationary front

• Storms: Regional atmospheric disturbances characterized by strong winds and precipitation.

• Cyclones: huge rotating masses of low pressure in which winds converge and ascend.

Extratropical Cyclone• Form between each hemisphere’s polar

and Ferrell cells

• occur in winter

• from 1000-2500 km in diameter (625-1600 mi.)

• In North America = nor’easters

• Example: “Perfect Storm”

Perfect Storm

The storm—created from a collision between a high

pressure system, a low pressure system and the

remnants from a dying hurricane—sent high winds and

Atlantic Ocean waves crashing into the East Coast, from

New England to Cape Hatteras, North Carolina.

The Perfect Storm

Tropical Cyclones• Great masses of warm, humid rotating air

• Hurricanes in Atlantic

• Typhoons in Pacific

• Tropical Cyclones in Indian Ocean

• Willi-willis in Australia

• less force = tropical depression --> tropical storm

• Hurricane status = 74 mph

• = most powerful storm on earth

• 20 billion metric T of water/day

• Danger: storm surge

high winds

rain

• Eye: calm, wind shifts direction

• On land, weakens due to surface friction, no power source.

1813-189-126-84-5Surge

(feet)

CatastrophicExtremeExtensiveModerateMinimalDamage

155131-155111-13096-11074-95Wind

(mph)

919944-920964-945979-965 980Pressure

(mb)

54321Category

The Saffir-Simpson Scale

Squall• Sudden increase in wind speed by 16 knots,

rising to 22 knots or more and lasting for at least 1 minute---then diminishes.

• Associated with cold fronts• sharp drop in temp.• roll shaped cloud• rain shower• may be snow

Florida, U.S.A Squall Line

Target Name: Earth

Spacecraft: Space Shuttle

Produced by: NASA

Copyright: NASA Copyright Free Policy

Cross Reference: STS41C-40-2130

Date Released: April 1984

Practical Considerations• Preventions:

evacuations

dikes

gate in Thames

other precautions?

Decision: prevention or cleanup?

Should historically proned areas be vacated?

Hurricane Katrina

Hurricane Ivan

Hurricane Frances

September 2004

Hugo

Hugo

Hugo

Hurricane Ivan

Ivan