Air-Sea Interactions:
Points to Remember:
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Water takes longer to heat up and cool down than land due to hydrogen bonds
Warm air can hold more water vapor than cold air
Uneven heating of the Earth’s surface leads convection/winds
Global Wind Patterns: Doldrums, Trade Winds, Westerlies, Easterlies
The Coriolis Effect will cause northward and southward traveling objects/wind a curved
perceived curved trajectory
Global Conveyor Belt’s movement based on salinity and temperature differences
Vertical Motion of the Air:
Atmospheric Circulation Cells: six distinct air masses (three in each hemisphere) with individual
airflow patterns
Hadley Cells:
1. Air rises from the equator (creating the Doldrums)
2. Moves towards the poles due to convection
3. Sinks at about 30 degrees latitude due to
cooling and moisture loss (creates deserts)
4. Moves back towards equator
5. Bends right as it heads to the equator creating
Trade Winds
Ferrel Cells:
1. Some air that rose of the equator continues
towards the poles
2. Bends to the right creating the Westerlies
Polar Cells:
1. Warm air rises at 60 degrees latitude and flows
towards to the poles
2. It cools and descends at the poles and heads back towards the equator, deflected right
creating the Polar Easterlies
Intertropical Convergence Zone:
Intertropical Convergence Zone: Vertical motion of the air near the equator that releases large
amounts of heat and moisture into the atmosphere
 Strongly influences climate, weather, and the seasons
 Constantly shifting above and below the equator due to land masses
 Atmospheric circulation symmetrical above and below the equator
El Nino Southern Oscillation (ENSO):
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
equator, winds blowing towards the
equator parallel to South American
coast, creates a rising thermocline
called an upwelling (rising of nutrient
rich/cold seawater)
 Upwelling makes the temperature of
surface water cooler
 Warm water builds up in the 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 reach surface with
cold water, causing Eastern Pacific to
be warmer
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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 round 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
ecosystem
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 and Cyclones:
Monsoons: Seasonal wind pattern changes caused by heating or cooling on the continents that
lead to predictable times of massive rainfall or dry conditions
 Result in summers with significant rainfall and winters with very little
 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 the winter.
Cyclones: Large rotating storm centers of low pressure air with converging winds at the center,
known to us as Hurricanes (typhoons in Asia)
Two Types:
1. Tropical – cyclones that form within a single atmospheric cell and can lead to
hurricanes
2. Extratropical – cycles that form in high latitudes, not as severe, lead to “nor’ easters”
Tropical Cyclones:
1. Moist winds get drawn into a low pressure area (air moves
from high to low pressure)
2. The Coriolis effect causes the winds to spiral inward and
counter clockwise in the Northern Hemisphere
3. Warm air rises in the center via convection causing rain
4. The formation of rain heats the atmosphere which causes air
pressure to continue to decrease and pull more air into the
system
5. So long as there is moisture and heat, the process continues
to intensify, possibly into a hurricane
Simple Explanation:
1. The sun heats the ocean, the ocean heats the air above it, warm air rises
2. Warm air is less dense and therefore rises thus it has a lower pressure
3. As the moist air rises, it condenses and forms clouds and precipitation
4. Air rushes in to replace the air that rose and brings with it more moisture and heat
from surrounding ocean
5. The air rushing air deflects right due to Coriolis Effect
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:
a. Tropical disturbance – a low pressure system with a group of storms, no rotation
b. Tropical depression – a tropical cyclone with max sustained winds of 38 mph
c. Tropical storm – a tropical cyclone with max sustained winds of 39-73 mph (naming
stage)
d. Hurricane – a tropical cyclone with max sustained winds of 74-110 mph
e. Major Hurricane – a tropical cyclone with max sustained winds of 111+, Category 3 or
above
Path of a Hurricane:
Trade winds direct it initially towards the west, then as it increases in latitude, Westerlies
push it East
Saffir-Simpson Scale:
Categories of hurricanes are determined by wind speed and air pressure. The resultant of
which can determine storm surges and potential damage.
Naming System:
 Named alphabetically
 Alternate boy/girl
 Retire names of the worst storms