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Atmosphere, Seasons & Circulation. Ms. Levensailor. Ocean and Atmosphere. Interact with each other. Water evaporated from the ocean enters the atmosphere. This impacts climates on land. Atmosphere is composed of: Nitrogen (78%) Oxygen (21%) Water vapor (1%). Atmospheric Movement. - PowerPoint PPT Presentation
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Atmosphere, Seasons & Circulation
Ms. Levensailor
Ocean and AtmosphereInteract with each other.
Water evaporated from the ocean enters the atmosphere.
This impacts climates on land.Atmosphere is composed of:
Nitrogen (78%) Oxygen (21%)Water vapor (1%)
Atmospheric MovementMoves in response
to:Uneven solar
heatingEarth’s rotation
Solar heating of Earth varies with latitude.
Solar Heating & SeasonsSolar heating varies
with seasons
Large Scale Atmospheric CirculationWarm air rises and cool air sinks.
Warm air expands and becomes less dense.Cool air contracts and becomes more dense.
Convection currents: circular current of air.
Convection CurrentsIf uneven solar
heating was the only factor in Earth’s air circulation it would look like this
Earth’s Rotation Plays a RoleCoriolis effect: eastward rotation of Earth
on its axis deflects the moving air or water away from its initial course.
Coriolis effect:Northern Hemisphere: curve is to the right
(clockwise)Southern Hemisphere: curve is to the left
(counterclockwise)
Coriolis Effect Influences the movement of air in
atmospheric circulation cells.Air rising from the equatorial region moves
poleward and is gradually deflected eastward.Turns right in the Northern Hemisphere.Turns left in the Southern Hemisphere.
Coriolis Effect on Air CellsCirculation cells are
large circuits of air.There are 3 cells in
each hemisphere:Hadley cellsFerrel cellsPolar cells
Atmospheric Circulation Cells generate large
scale surface wind patterns.
Trade winds (easterlies) centered at 15° N and 15° S latitudes.Surface winds of the
Hadley cells. Westerlies centered at
45° N and 45° S.Surface winds of the
Ferrel cells.
Circulation of the Ocean
Mass flow of Ocean WaterKnown as ocean currents.Driven by wind and gravity!Surface currents: wind-driven movement of
ocean water at or near the ocean’s surface.Thermohaline currents: slow, deep
currents that affect the bulk of seawater below the surface.Depends on density differences as a result of
temperature and salinity.
Surface Currents10% of the water in the ocean is involved in
surface currents.Water flowing horizontally in the upmost 400
meters.Responsible force: WIND!
Surface winds form global patterns within latitude bands.
Northern Hemisphere surface currents flow to the right.
Southern Hemisphere surface currents flow to the left.
Continents block continuous flow and creates a circular pattern (GYRE).
Ocean Layers & Gyre
Ekman SpiralA body of water can be
thought of as a set of layers.Top layer driven by wind.Each layer below is moved
by friction. Moving at a slower speed
and at an angle to the layer immediately above it.
Horizontal movements in a layered water column.Each layer moving in a
slightly different direction.
Seawater flows in 6 surface circuits2 in the Northern
Hemisphere.4 in the Southern
Hemisphere.
Antarctic Circumpolar is not a gyre.
Direction of currents
Boundary CurrentsWestern Boundary Currents: Gulf stream
Narrow, fast, deep currents.Move warm water poleward.
Eastern Boundary Currents: California currentCarry cold water equatorwardShallow and broad.