Air and Sea Interactions

Air and Sea Interactions2012Discuss with your partnerWhat is the difference between climate and weather?

Ocean MotionConstant Movement, more in some places then others.Three FactorsWindsCoriolis EffectCurrent

AtmosphereWinds are named for the direction in which they blow from.Convection Current - Moves materials around. Cells move air in the atmosphere around.

Atmospheric CellsAir movement into the atmosphere and back down.Atmospheric CellsTell me as much as you can about each cell type based on what you see on the following slide:Hadley CellsFerrel Cells Polar Cells

Why is it not just one large cell.What goes up must come down.The cycle:Warm air risesless dense.Eventually this warm air cools off.Cool air is more dense and sinks down.Connecting Air CellsThree major connectionsMeeting Air Currents Hadley to HadleyIntertropical Convergence Zone Trade winds from both hemispheres converge together.Gentle Breeze

DoldrumsWind dies down and ships are stuck in the ITCZ

Meeting Air Currents Hadley to FerrelHorse Latitudes 30N and 30SAlso called Subtropical High Winds separating in different directions.Dry air and high pressure results in weak winds. Desert areas

Why were they called the horse latitudes?Meeting Air Currents Ferrel to PolarCold air masses from higher latitudes and warmer air masses from lower latitudesAreas of storm activityWind PatternsMovement of air across the globe.Different air flow convergence and divergence gives us our general climate conditions.

Wind PatternsTell me as much as you can about each wind pattern based on what you see on the following slide:Trade Winds Northeasterly and SoutheasterlyWesterliesEasterlies (Polar)

Ocean MotionCurrents are named by the direction they flow2 Types: Surface Currents Deep Sea CirculationOcean Vertical StructureTop Ocean Layer well mixed because of air interactions.Pycnocline Area between the mixed layer and deep ocean layer. Major changes in density and salinity occur hereIncreasing density.Thermocline - Temp ChangesHalocline Salinity ChangesGlobal Conveyor BeltOverall circulation to transport heat and salt.

Cold salt water is more dense, then the less dense warmer waters. (More oxygen and nutrients in colder water as well)

Flows top to bottom and along the surface.

Begins near Greenland 1000 years to complete a cycle.

Coriolis EffectDue to Earths rotation.

Shallow layer of the surface water is deflected to the right in the Northern hemisphere and to the left in the Southern hemisphere

At the equator this effect is at zero.

Wind bombards the surface ocean Water starts to move Coriolis deflection alters its pathWhat happens UNDER the surface?Ekman Transport (Spiral) surface layer (1) drags onthe water underneath (2). layer 2 starts to move. It moves more slowly than layer 1 due to friction.(smaller yellow arrow) Coriolis deflectionalters path of layer 2.

Decreases as you move down the water column.UpwellingAs surface waters are pushed offshore, water is drawn from below to replace them. Good: Upwelling brings up cold, nutrient-rich waters to the surface, which encourage seaweed growth and support blooms of phytoplankton.Bad: upwelling that moves surface water offshore can potentially move drifting larvae long distances away from their natural habitatMost common on West CoastAbout half the world's total fish catch comes from upwelling zones.

DownwellingWhere Ekman transport moves surface waters toward the coast, the water piles up and sinks.

The surface layer of warm, nutrient-deficient water thickens as water sinks.

Reduces biological productivity and transports heat, dissolved materials, and surface waters rich in dissolved oxygen to greater depths.Returns oxygen poor water to be recycled

Boundary CurrentsWestern Currents Gulf Stream, Kuroshio, East Australia Currents warm water moving from equator to pole narrow: < 100 km wide deep: down to 2 km fast: 100s of km/day sharp boundaries defined by water temperatureEastern Currents California, Canary, Peru Currents cold water moving from pole to equator wide: ~ 1000 km wide shallow: < 500 m slow: 10s of km/day diffuse boundaries

Wind TricksMaking a GyreGyresFormed by major currents interacting with each other.Deflection is piling up water (Coriolis Effect).Gravity is pulling it down.The pile is ALWAYS THERE. These forces must be EQUAL.

Geostrophic FlowSargasso Sea - a mound of water in the Atlantic Ocean

Major Gyres (5)

Notice how the winds are helping the currents

Wind Trick #2Western IntensificationWhat happens when you push in on a plastic container of water?

The container moves first, and water moves a fraction of a second later.Water sloshes up again the left-hand side, creating a pile

Sverdrup et al., Introduction to the Worlds Oceans, 8th edition, McGraw Hill, Fig. xxxEarths rotationAs Earth rotates the continents smack into the oceans Asia, Australia hit thePacific OceanThe Americas hit theAtlantic OceanContinents crash into the mound of water.The mound is asymmetrical.This leads to Western Intensification water piles up on the coastWestEastNorthAmericaA West to East Cross Section of the mound of water1mOnly ~ 1m high, but thats enough to create BIGdifferences in the currents.Western IntensificationWestEastNorthAmericaA West to East Cross Section of the mound of waterGravity is trying to pull this down and out to flatten the ocean.The flow is constricted on the WEST side and spread out on the EASTThink about constricting flow out of a garden hose by covering halfthe opening with your thumb. The constricted flow moves FASTER.Western IntensificationWestEastNorthAmericaThink about constricting flow out of a garden hose by covering halfthe opening with your thumb. The constricted flow moves FASTER.WHY?SAME AMOUNT of water forced to move through smaller openingCanary Current(Flowing OUT of screen)diffuse, slowGulf Stream(Flowing into screen)Narrow and fastThe Southern OscillationPattern of reversing surface air pressure between the eastern and western tropical pacificEl NinoSpanish for The Christ Childwhy?Unusually warm ocean temperaturesResults: Major rainfall, flooding, across the southern US and in Peru.Drought in the West Pacific, can cause devastating brush fires in Australia.Normal vs. Nino

La Ninaunusually cold ocean temperaturesEastern Pacific is cooler than usual, and the cool water extends farther westward than is usualWetter than normal conditions across the Pacific Northwest Dryer and warmer than normal conditions across much of the southern tier.Normal vs. Nina

DefinitionCharacteristicsExamplePictureWord Made by nameWhen you feel you are finished, you will switch with someone that has a different word as yourself.You will add 1 thing to it and then write at the bottomChecked by your name.