air & sea interactions

Air & Sea Interactions

Points to Remember Water takes longer to

heat up and cool down due to hydrogen bonds

Points to Remember Warm air can hold more water vapor than cold air

Points to Remember Uneven heating of the Earth’s surface leads to

wind/convection

Points to Remember Global Wind Patterns:

o Doldrumso Trade Windso Westerlieso Easterlies

Points to Remember The Coriolis Effect will cause northward and

southward traveling objects/wind to have a perceived curved trajectory

Points to Remember Global Conveyor Belt’s movement is based on

salinity and temperature differences.

Atmospheric Circulation Cells

Six distinct air masses (three in each hemisphere) with individual airflow patterns

Hadley Cells Air rises from equator

(doldrums) Moves towards the poles

due to convection Sinks at 30 degrees

latitude due to cooling and moisture loss (creates deserts)

Moves back towards the equator

Bends right as it heads towards the equator creating Trade winds

Ferrel Cells Some air that rose

at the equator continues towards the poles

Bends to the right creating the Westerlies

Polar Cells Warm air rises at 60

degrees latitude and flows towards to the poles

It cools and descends at the poles and heads back towards the equator, deflected right to form the polar easterlies

Intertropical Convergence Zone

Vertical motion of the air near the equator that releases large amounts of heat and moisture into the atmosphereo Strongly influences climate, weather, and the seasonso Constantly shifting above and below the equator due to

land masseso Atmosphere circulation symmetrical above and below

the ITCZ not the equator

Intertropical Convergence Zone

El Nino Southern Oscillation

El Nino - A build up of warm water in the oceans near the equator just east of Asia which leads to global weather and climate changes

Occurs every three to eight years

Normal Conditions: Trade winds blow strongly along the equator,

winds blowing parallel to South American coast creates a rising thermocline called an upwelling (rising of nutrient rich/cold seawater)

Normal Conditions: Upwelling makes the temperature of surface water cooler Warm water builds up in Western Pacific Results in low pressure and high rainfall in Western Pacific

(Southeast Asia) and high pressure and low rainfall in Eastern Pacific (Americas)

El Nino Conditions Trade winds weaken, stop or reverse course (blow

East) Warm water that is normally pushed west now

spreads out into the ocean and towards the East Thermocline deepens as a result and upwelling

does not reach surface with cold water, causing Eastern Pacific to be warmer

El Nino Conditions Since there is less of a temperature difference between the

Western and East Pacific, trade winds become even more weak Results in more rain and warmer temperatures in the Americas Arrives around Christmas time (called the current of the little

boy/Christ child, hence the name El Nino) Loss of nutrients from the loss of upwelling collapses the fishing

industry and marine ecosystems

Global Effects of El Nino

Causes the hottest part of the troposphere to move 1/3 around the world

Leads to extensive extreme weather conditions, flooding, tornados, and drought

Destroys ecosystems

La Nina After an El Nino, the normal conditions return in

extreme forms leading to colder than normal ocean conditions in the Eastern Pacific

Monsoons Seasonal wind pattern changes caused by

heating or cooling on the continents that lead to predictable times of massive rainfall or dry conditionso Results in summers with significant rainfall and winters

with very littleo Caused by air heated by landmass rises and is replaced

by warm, moist air from the ocean, which in turn rises and causes rainfall, Cycle reverses in winter

Cyclones Large rotating storm centers of low pressure air,

with converging winds at the center, known as hurricanes (Asia – Typhoons)

Two Types:o Tropical –cyclones that form within a single atmospheric

cello Extratropical – cycles that form in high latitudes, not as

severe, lead to “nor’easters”

Tropical Cyclones Moist winds get drawn

into a low pressure area (air moves from high to low pressure)

The Coriolis Effect causes the winds to spiral inward and counter clockwise in the Northern Hemisphere

Warm air rises in the center via convection causing rain

Tropical Cyclones The formation of rain heats the atmosphere which

causes air pressure to continue to decrease and pull more air into the system

So long as there is moisture and heat, the process continues to intensify, possibly into a hurricane

Simple Explanation1. The sun heats the ocean, the ocean heats the

air, the air rises2. Warm air is less dense and therefore it rises and

thus it has a low pressure3. As the moist air rises, it condense and forms

clouds and precipitation4. Air rushes in to replace the air that rose, and

brings with it more heat and moisture5. The air rushing in deflects to the right due to the

Coriolis Effect causing a counter-clockwise rotation

6. This leads to a tropical cyclone

Hurricane Recipe: Area of warm water Winds affected by the Coriolis Effect (no

hurricanes at the equator nor can they cross the equator)

A collection of storms

Tropical Cyclone Designations

Tropical Disturbance – a low pressure system with a group of storms, little to no rotation

Tropical Depression – A tropical cyclone with max sustained winds up to 38 mph

Tropical Storm – A tropical cyclone with max sustained winds of 39-73 mph (naming stage)

Hurricane – A tropical cyclone with max sustained winds of 74-110 mph

Major Hurricane – A tropical cyclone with max sustained winds of 111+ mph, Category 3 or above

Path of a Hurricane Trade winds direct it

initially to the west, then as it increases in latitude, Westerlies will push it East

Saffir-Simpson Scale Categories of hurricanes are determined by wind

speed and air pressure. The resultant of which determine storm surge and potential damage

Naming System Named alphabetically Alternate boy/girl Retire names of the worst storms