Things we will learn about the Things we will learn about the oceans (and their role in climate)oceans (and their role in climate)

E4.2A E4.2A Describe the major causes for the ocean’s surface and deep water Describe the major causes for the ocean’s surface and deep water currents, including the prevailing winds, the Coriolis effect, unequal heating of currents, including the prevailing winds, the Coriolis effect, unequal heating of the earth, changes in water temperature and salinity in high latitudes, and basin the earth, changes in water temperature and salinity in high latitudes, and basin shape. shape.

E4.2B E4.2B Explain how interactions between the oceans and the atmosphere Explain how interactions between the oceans and the atmosphere influence global and regional climate. Include the major concepts of heat influence global and regional climate. Include the major concepts of heat transfer by ocean currents, thermohaline circulation, boundary currents, transfer by ocean currents, thermohaline circulation, boundary currents, evaporation, precipitation, climatic zones, and the ocean as a major CO2 evaporation, precipitation, climatic zones, and the ocean as a major CO2 reservoir. reservoir.

E4.2c E4.2c Explain the dynamics (including ocean-atmosphere interactions) of the Explain the dynamics (including ocean-atmosphere interactions) of the El Niño-Southern Oscillation (ENSO) and its effect on continental climates. El Niño-Southern Oscillation (ENSO) and its effect on continental climates.

E4.2d E4.2d Identify factors affecting seawater density and salinity and describe how Identify factors affecting seawater density and salinity and describe how density affects oceanic layering and currents. density affects oceanic layering and currents.

E4.2e E4.2e Explain the differences between maritime and continental climates with Explain the differences between maritime and continental climates with regard to oceanic currents. regard to oceanic currents.

E4.2f E4.2f Explain how the Coriolis effect controls oceanic circulation. Explain how the Coriolis effect controls oceanic circulation.

OceansOceans

Early HistoryEarly History

It is believed by many It is believed by many scientists that the oceans scientists that the oceans formed when formed when VOLCANOESVOLCANOES released released HUGE amounts of HUGE amounts of WATER VAPORWATER VAPOR and and CO2CO2. .

Over the course of Over the course of hundreds of millions of hundreds of millions of years, years, CONDENSATIONCONDENSATION of these gases occurred, of these gases occurred, precipitation fell and the precipitation fell and the low areas of the surface low areas of the surface began to fill. began to fill.

Other evidence suggests Other evidence suggests that billions of that billions of COMETSCOMETS collided with Earth. collided with Earth.

They contain a small They contain a small percentage of water (about percentage of water (about 0.5%). 0.5%).

If enough of them collided If enough of them collided with Earth, they could have with Earth, they could have added enough water vapor added enough water vapor to the molten material to the molten material beneath the surface to beneath the surface to create the oceans during create the oceans during VOLCANIC ERUPTIONSVOLCANIC ERUPTIONS

World OceansWorld Oceans The world’s oceans are The world’s oceans are

actually all connected. actually all connected. We can divide them into We can divide them into

many “different” bodies many “different” bodies of waterof water– N. PacificN. Pacific– S. PacificS. Pacific– N. AtlanticN. Atlantic– S. AtlanticS. Atlantic– IndianIndian– ArcticArctic– AntarcticAntarctic

Seas are parts of the Seas are parts of the oceans that are oceans that are surrounded by landsurrounded by land

Ocean FactsOcean Facts 9797 % of the water found on % of the water found on

earth is found in the oceans. earth is found in the oceans. The remaining water makes up The remaining water makes up ALL of the lakes, rivers, and ALL of the lakes, rivers, and streams, as well as all the streams, as well as all the groundwater, all the water groundwater, all the water trapped as ice, and all the water trapped as ice, and all the water vapor in the atmosphere. vapor in the atmosphere.

The oceans cover The oceans cover 7171 % of % of Earth’s surface (139 million sq Earth’s surface (139 million sq mi).mi).

The average depth is about The average depth is about 12,000 ft.12,000 ft.

The deepest trench is the The deepest trench is the Mariana Trench in the western Mariana Trench in the western PacificPacific

Ocean ChemistryOcean Chemistry The average salinity of the world’s The average salinity of the world’s

oceans is about oceans is about 3535 ppt, or ppt, or 3.53.5 %. %. The two most common “salts” are…The two most common “salts” are… 1. 1. CHLORIDECHLORIDE 2. 2. SODIUMSODIUM But the oceans also contain lesser But the oceans also contain lesser

amounts of “salts” such as…amounts of “salts” such as… 1. 1. SULFATESULFATE 2. 2. MAGNESIUMMAGNESIUM 3. 3. POTASSIUMPOTASSIUM 4. 4. CALCIUMCALCIUM These “salts” enter the ocean by These “salts” enter the ocean by

way of way of RIVERSRIVERS

The Ocean as a CO2 Reservoir The Ocean as a CO2 Reservoir

Remember that Mother Remember that Mother Nature likes to keep Nature likes to keep things in balancethings in balance

As is the case with As is the case with MANY aspects of MANY aspects of planet Earth, there are planet Earth, there are interactions that help interactions that help maintain balancemaintain balance

The atmosphere and The atmosphere and the oceans work the oceans work together to maintain a together to maintain a balance of CO2balance of CO2

CO2 Reservoir cont…CO2 Reservoir cont… There is a relatively SMALL amount of There is a relatively SMALL amount of

CO2 in our atmosphere because the CO2 in our atmosphere because the oceans absorb a lot of itoceans absorb a lot of it

Things like…Things like…– AlgaeAlgae– PlantsPlants– Shell-Making OrganismsShell-Making Organisms

use the carbon and release the oxygen use the carbon and release the oxygen back into the water and the airback into the water and the air

Without this interaction, Earth could Without this interaction, Earth could have a runaway greenhouse effect and have a runaway greenhouse effect and might be more like Venus (surface might be more like Venus (surface temperatures of 700 degrees, sulfuric temperatures of 700 degrees, sulfuric acid rain, etc…)acid rain, etc…)

Surface CurrentsSurface Currents Surface currents are Surface currents are

created by the wind and created by the wind and the rotation of the earth. the rotation of the earth.

Gyers are circular Gyers are circular patterns (whirlpools) in patterns (whirlpools) in the oceans the oceans – Clockwise in the Clockwise in the

northern hemispherenorthern hemisphere– Counter-Clockwise in Counter-Clockwise in

the southern the southern hemispherehemisphere

Gyers/Surface Currents Gyers/Surface Currents bring warm air masses to bring warm air masses to cool regions, and vice-cool regions, and vice-versaversa

The Antarctic Circumpolar CurrentThe Antarctic Circumpolar Current

This surface current This surface current connects the southern connects the southern oceansoceans

It keep warm water It keep warm water away from Antarctica away from Antarctica

Waves and TidesWaves and Tides

On the surface, On the surface, WAVESWAVES are the most are the most obvious evidence of obvious evidence of these “currents”. these “currents”.

Tides also play a role Tides also play a role in surface currents , in surface currents , which are controlled by which are controlled by the interaction the interaction between the between the EARTHEARTH and the and the MOONMOON. .

Density CurrentsDensity Currents There are also density currents There are also density currents

in the world’s oceans that move in the world’s oceans that move from the surface to the depths, from the surface to the depths, and back to the surface.and back to the surface.

SALINITYSALINITY is one factor that is one factor that determines seawater density determines seawater density while, while, TEMPERATURETEMPERATURE is the is the other other

The shape of the ocean floors The shape of the ocean floors (also called “Ocean Basins”) (also called “Ocean Basins”) plays a role in the movement of plays a role in the movement of deep-water currentsdeep-water currents

Seawater density is a tough thing to Seawater density is a tough thing to calculate…calculate…– In tropical parts of the world, water In tropical parts of the world, water

temperature is higher, causing the temperature is higher, causing the water to become less dense. water to become less dense.

– But, higher temperatures create But, higher temperatures create higher salinity levels ( because higher salinity levels ( because rates of evaporation are higher), rates of evaporation are higher), which makes the water more dense. which makes the water more dense.

On the other hand…On the other hand…– In polar regions of the world, water In polar regions of the world, water

temperature is cooler, which makes temperature is cooler, which makes seawater more dense, seawater more dense,

– But, where cold mountain But, where cold mountain streams/rivers dump freshwater into streams/rivers dump freshwater into polar oceans, the salinity levels are polar oceans, the salinity levels are lower because seawater is diluted. lower because seawater is diluted.

This is what the movie Day After This is what the movie Day After Tomorrow was talking about…Tomorrow was talking about…

Currents and ClimatesCurrents and Climates

Both Surface Currents Both Surface Currents and Density Currents and Density Currents move water and air move water and air masses around the masses around the globe.globe.

Climates are controlled Climates are controlled by the movement of by the movement of water, and the air water, and the air masses that form over masses that form over themthem

Global WindsGlobal Winds

Global Wind Global Wind Patterns also Patterns also play a large roll play a large roll in the movement in the movement of ocean water of ocean water (affecting (affecting climate)climate)– The Trade WindsThe Trade Winds– The WesterliesThe Westerlies– The Polar The Polar

EasterliesEasterlies

World ClimatesWorld Climates

ClimateClimate Simply put… climate is the average Simply put… climate is the average

of the weather for a particular of the weather for a particular location location

You must have at least 30 years of You must have at least 30 years of data to properly classify a climatedata to properly classify a climate

TemperatureTemperature and and precipitationprecipitation are are the most important elements in the most important elements in climate descriptions.climate descriptions.

Why?Why?– Greatest influence on people and Greatest influence on people and

their activities.their activities.– Important impact on the Important impact on the

distribution of vegetation and the distribution of vegetation and the development of soils.development of soils.

ClimateClimate

While the concept of climate is fairly While the concept of climate is fairly easy to understand, the controls of easy to understand, the controls of climate are rather detailed.climate are rather detailed.

We must look at the following…We must look at the following…– Global Wind PatternsGlobal Wind Patterns– Global Pressure SystemsGlobal Pressure Systems– Ocean Surface CurrentsOcean Surface Currents– Ocean Density CurrentsOcean Density Currents– CO2 InteractionsCO2 Interactions– The Coriolis Effect The Coriolis Effect – LatitudeLatitude– The Earth’s Tilt on its AxisThe Earth’s Tilt on its Axis– Altitude & MountainsAltitude & Mountains– Proximity to an ocean, sea or large lake Proximity to an ocean, sea or large lake

(such as the Great Lakes)(such as the Great Lakes)– Air Masses Air Masses

Climate ControlsClimate ControlsLatitudeLatitude– This is the NUMBER ONE This is the NUMBER ONE

factor of climatefactor of climate– Fluctuations in the amount Fluctuations in the amount

of solar radiation received at of solar radiation received at Earth surface represent the Earth surface represent the single greatest cause of single greatest cause of temp differences.temp differences.

– Varied factors include:Varied factors include: Cloud coverage.Cloud coverage. Amount of dust in the air.Amount of dust in the air. Seasonal changes in sun Seasonal changes in sun

angle and length of daylight.angle and length of daylight.

Latitude and TemperatureLatitude and Temperature

Latitude plays a large role in temperatureLatitude plays a large role in temperature ““Tropical” is used to describe warm climates near the Tropical” is used to describe warm climates near the

equatorequator ““Subtropical” is a term used to describe climates at or near Subtropical” is a term used to describe climates at or near

3030° of N & S Latitude° of N & S Latitude ““Mild” is often used to describe climate that are influenced Mild” is often used to describe climate that are influenced

by air masses that move in off the water (less fluctuation by air masses that move in off the water (less fluctuation between highs and lows)between highs and lows)

““Continental” is used to describe climates of areas in the Continental” is used to describe climates of areas in the interior of continents (lots of variation between daytime interior of continents (lots of variation between daytime highs and lows, and seasonal highs and lows)highs and lows, and seasonal highs and lows)

““Polar” is used to describe cold climates (areas at high Polar” is used to describe cold climates (areas at high latitudes)latitudes)

Climate ControlsClimate Controls

Coastal vs. Interior Coastal vs. Interior

locationlocation– Land heats up more rapidly and to Land heats up more rapidly and to

higher temps than water.higher temps than water.– Variations in temp are greater over land Variations in temp are greater over land

than water.than water.– Marine climates are considered mild for Marine climates are considered mild for

their latitudes.their latitudes.– Continental climates tend to be more Continental climates tend to be more

extreme.extreme.– Differential heating has a significant Differential heating has a significant

influence on pressure & wind systems.influence on pressure & wind systems.– This can cause two cities of the same This can cause two cities of the same

altitude and latitude to have different altitude and latitude to have different climatesclimates

AltitudeAltitude

Remember that Remember that temperature drops as temperature drops as you rise into the you rise into the troposphere (about 10troposphere (about 10° ° for every 1000 meters)for every 1000 meters)

Cities at a higher Cities at a higher altitude will have a altitude will have a different climatedifferent climate

Compare Denver Compare Denver (5,280 feet) and (5,280 feet) and Indianapolis (714 feet)Indianapolis (714 feet)

Climate ControlsClimate Controls

Geographic PositionGeographic Position– Water has more Water has more

influence along the influence along the windward side of a windward side of a continent (maritime air continent (maritime air moves inland).moves inland).

– On the lee side of a On the lee side of a continent, winds blow continent, winds blow from the land toward the from the land toward the ocean (continental air ocean (continental air moves seaward).moves seaward).

Climate ControlsClimate Controls

Mountains and HighlandsMountains and Highlands– Topographic barriers trigger Topographic barriers trigger

orographic rainfall on the orographic rainfall on the windward slopes, leaving a windward slopes, leaving a dry rain shadow on the dry rain shadow on the leeward side.leeward side.

– Highlands create their own Highlands create their own climatic regions because of climatic regions because of the drop in temp with the drop in temp with increased altitude, areas are increased altitude, areas are generally cooler and drier generally cooler and drier than surrounding locations.than surrounding locations.

Climate ControlsClimate Controls

Global Wind Global Wind Patterns also Patterns also play a large roll play a large roll in climatein climate– The Trade WindsThe Trade Winds– The WesterliesThe Westerlies– The Polar The Polar

EasterliesEasterlies

Hadley CellsHadley Cells Hadley Cells are associated with Hadley Cells are associated with

High and Low Pressure Systems High and Low Pressure Systems AND Global WindsAND Global Winds

They play a VERY LARGE role in They play a VERY LARGE role in climateclimate– These are the convection currents These are the convection currents

present in the individual wind beltspresent in the individual wind belts Think about the rising of warm air Think about the rising of warm air

and the sinking of cool air and how and the sinking of cool air and how High and Low pressure have similar High and Low pressure have similar movementsmovements– Tropical Low near the equator Tropical Low near the equator

(rainforests)(rainforests)– Polar High near the polesPolar High near the poles– Subtropical High near 30Subtropical High near 30° (deserts)° (deserts)– The ITCZ (Intertropical Convergence The ITCZ (Intertropical Convergence

Zone) is an area near the equator Zone) is an area near the equator where air masses convergewhere air masses converge

Compare Hadley Cells and Compare Hadley Cells and VegetationVegetation

Climate ControlsClimate Controls

Ocean CurrentsOcean Currents– Poleward moving currents Poleward moving currents

(warm) cause air temps to (warm) cause air temps to be warmer than would be be warmer than would be expected for their latitudes.expected for their latitudes. Greater influence during Greater influence during

winter months.winter months.

– Cold currents act to create Cold currents act to create and stabilize air masses and stabilize air masses moving across them.moving across them.

Climate Graphs Climate Graphs A city at high latitude A city at high latitude

(cold areas near the (cold areas near the poles)poles)

A City south of the A City south of the equatorequator

A city with a mild climate A city with a mild climate (maybe near an ocean)(maybe near an ocean)

A city with a climate like A city with a climate like DetroitDetroit

A city with a climate A city with a climate near the equatornear the equator