Currents and ClimateCurrents and Climate

CurrentsCurrents Large streams of Large streams of

moving water that moving water that flow through the flow through the oceans oceans

Move the Sun’s energy Move the Sun’s energy from the equator to from the equator to the polesthe poles

cold water from the cold water from the poles poles the equatorthe equator

Moderate the climate Moderate the climate of our planetof our planet

Two types: surface & Two types: surface & deepdeep

Horizontal, stream-like Horizontal, stream-like movements of water movements of water that occur at or near that occur at or near the surface of the oceanthe surface of the ocean

Surface CurrentsSurface Currents

Causes: Global WindsCauses: Global Winds

Wind drives Wind drives surface currents, surface currents, (to the depth of (to the depth of several hundred several hundred meters)meters)

Different winds Different winds cause currents to cause currents to flow in different flow in different directionsdirections

Near the equator, Near the equator, winds blow E to Wwinds blow E to W

Close to the poles, Close to the poles, W to EW to E

Causes: Coriolis EffectCauses: Coriolis Effect

Earth’s rotation Earth’s rotation causes wind & causes wind & surface currents surface currents to move in to move in curved pathscurved paths

North hemisphere: North hemisphere: clockwiseclockwise

Southern Southern hemisphere hemisphere counterclockwisecounterclockwise

http://www.youtube.com/watch?v=mcPs_OdQOYU

Causes Continental DeflectionCauses Continental Deflection

Surface currents Surface currents meet continents, meet continents, the currents the currents deflect, or deflect, or change change direction.direction.

Causes: TemperaturesCauses: Temperatures Warm-water currents near the equator/carry Warm-water currents near the equator/carry

warm water to other parts of the oceanwarm water to other parts of the ocean Cold-water currents closer to the poles/carry cool Cold-water currents closer to the poles/carry cool

water to other parts of the oceanwater to other parts of the ocean

The Gulf StreamThe Gulf Stream Largest and most Largest and most

powerful surface current powerful surface current in the North Atlantic in the North Atlantic Ocean caused by strong Ocean caused by strong winds from the westwinds from the west

Carries warm water from Carries warm water from the Gulf of Mexico to the the Gulf of Mexico to the Caribbean Sea, then Caribbean Sea, then northward along the coast northward along the coast of the USof the US

Keeps Northern Europe Keeps Northern Europe much warmer in the much warmer in the winter than it would winter than it would otherwise beotherwise be

Ocean Current MapOcean Current Map

Deep Currents Stream like Stream like

movements of movements of ocean water located ocean water located far below the far below the surfacesurface

Not controlled by Not controlled by windwind

Form in parts of the Form in parts of the ocean where water ocean where water density’s density’s increasingincreasing.. Deep currents are

caused by changes in density.

Water DensityWater Density

The density of The density of ocean water is ocean water is affected by affected by temperaturetemperature and and salinitysalinity..

Both decreasing Both decreasing the the temperaturetemperature of ocean water of ocean water and increasing and increasing the water’s the water’s salinitysalinity will will increase the increase the water density.water density.

How do deep currents form?1) Decreasing Temperature: water cools, 1) Decreasing Temperature: water cools, becomes more dense and sinks eventually becomes more dense and sinks eventually traveling toward the equator as a deep traveling toward the equator as a deep current along the ocean floor.current along the ocean floor.

How do deep currents form?

2) Increasing Salinity Through Freezing: 2) Increasing Salinity Through Freezing: desolved solids from frozen water are desolved solids from frozen water are squeezed out of the ice and enter the liquid squeezed out of the ice and enter the liquid below which increases the salinity… it below which increases the salinity… it becomes more dense!becomes more dense!

How do deep currents form?

3) Increasing Salinity through 3) Increasing Salinity through evaporation: surface water evaporates evaporation: surface water evaporates leaving solids behind which make the leaving solids behind which make the water more dense. It sinks to the floor water more dense. It sinks to the floor forming a deep current. (Common in forming a deep current. (Common in warm climates.)warm climates.)

Surface Currents and Climate• Warm-Water Currents and Climate

Warm-water currents create warmer Warm-water currents create warmer climates in coastal areas that would climates in coastal areas that would otherwise be much cooler.otherwise be much cooler.

Surface Currents and Climate,

• Cold-Water Currents and Climate Cold-water currents keep climates along a Cold-water currents keep climates along a coast cooler than the inland climate year-coast cooler than the inland climate year-round.round.

Surface Currents and Climate, Upwelling is the is the

movement of deep, cold, movement of deep, cold, and nutrient-rich water and nutrient-rich water to the surface of the to the surface of the ocean.ocean.

The nutrients that are The nutrients that are brought to the surface brought to the surface support the growth of support the growth of plankton. Plankton plankton. Plankton support larger support larger organisms, such as fish organisms, such as fish and seabirds.and seabirds.

Upwelling is shown on Upwelling is shown on the next slide.the next slide.

Nature’s Climate ChangeNature’s Climate Change El Nino is an abnormal El Nino is an abnormal

climate event that occurs climate event that occurs every two to seven years every two to seven years in the Pacific Ocean.in the Pacific Ocean.

It begins when an unusual It begins when an unusual pattern of winds form over pattern of winds form over the western Pacific.the western Pacific.

This causes fast sheets of This causes fast sheets of warm water to move warm water to move eastward to the South eastward to the South American coast.American coast.

It can last one to two It can last one to two years.years.

Last one was from mid Last one was from mid 2009 to early 2010.2009 to early 2010.

El Niño El Niño - is the - is the

warming of water warming of water in the Pacific in the Pacific Ocean.Ocean.

Rain and flooding Rain and flooding along the Pacific along the Pacific coast coast

Warm water disrupts Warm water disrupts food chain of fish, food chain of fish, birds, and sea birds, and sea mammals mammals

Tornadoes and Tornadoes and thunderstorms in thunderstorms in southern US southern US

Fewer than normal Fewer than normal hurricanes in the hurricanes in the Atlantic Atlantic

La Niña La Niña - is the - is the

cooling of water cooling of water in the Pacific in the Pacific Ocean.Ocean.

Snow and rain on Snow and rain on the west coast the west coast

Unusually cold Unusually cold weather in Alaska weather in Alaska

Unusually warm Unusually warm weather in the rest weather in the rest of the USA of the USA

Drought in the Drought in the southwest southwest

Higher than normal Higher than normal number of number of hurricanes in the hurricanes in the Atlantic Atlantic

More El Niño

El Niño is a change in the is a change in the water temperature in the water temperature in the Pacific Ocean that Pacific Ocean that produces a warm current.produces a warm current.

Effects of El Niño El El Niño alters weather Niño alters weather patterns enough to cause patterns enough to cause disasters, including flash disasters, including flash floods, mudslides, and floods, mudslides, and droughts. El Niño also droughts. El Niño also prevents upwelling off the prevents upwelling off the coast of South America.coast of South America.

El Nino Impact (Western Coast of El Nino Impact (Western Coast of South America)South America)

El Nino can have El Nino can have disastrous disastrous consequences.consequences.

Warm surface water Warm surface water prevents upwelling off prevents upwelling off of the western coast of the western coast of South America.of South America.

Without nutrients Without nutrients brought up by brought up by upwelling, fish die or upwelling, fish die or go somewhere else to go somewhere else to find food.find food.

Sea birds have no fish Sea birds have no fish to eat, and also must to eat, and also must leave the area or die.leave the area or die.

El Nino Effects on Us!El Nino Effects on Us! El Nino causes shifts in weather patterns around the world, El Nino causes shifts in weather patterns around the world,

bringing severe conditions to different areas.bringing severe conditions to different areas. El Nino caused an unusually warm winter in northeastern El Nino caused an unusually warm winter in northeastern

U.S.U.S. It also brought heavy rains, flooding, and mud slides in It also brought heavy rains, flooding, and mud slides in

California.California. It also brought a string of deadly tornadoes in Florida.It also brought a string of deadly tornadoes in Florida.

Predicting El NiñoPredicting El Niño Studying and Predicting

El Niño Learning as much Learning as much as possible about El Niño is as possible about El Niño is important because of its important because of its effects on organisms and effects on organisms and land.land.

To study El Niño, scientist To study El Niño, scientist use a network of buoys use a network of buoys located along the equator. located along the equator. The buoys collect data about The buoys collect data about surface temperature, air surface temperature, air temperature, currents, and temperature, currents, and wind.wind.

Forecasting El NinoForecasting El Nino Scientist don’t fully Scientist don’t fully

understand the understand the conditions that create conditions that create El NinoEl Nino

They can predict its They can predict its occurrence by using occurrence by using computer models of computer models of the world climatethe world climate

Knowing when El Nino Knowing when El Nino will strike, officials will will strike, officials will give notice and can give notice and can plan for unusual plan for unusual weather patterns.weather patterns.

El Nino (2006 hurricane season)El Nino (2006 hurricane season) Why hasn’t there been many Why hasn’t there been many

hurricanes in the 2006 hurricanes in the 2006 hurricane season? hurricane season?

The seasonal activity was The seasonal activity was lower than expected because lower than expected because of the rapid development of El of the rapid development of El Nino.Nino.

This year there were only 9 This year there were only 9 named storms, 5 became named storms, 5 became hurricanes, and 2 became hurricanes, and 2 became major hurricanes in Category 3 major hurricanes in Category 3 or higher.or higher.

2005 was the most active 2005 was the most active season on record, with 28 season on record, with 28 named storms, of which 15 named storms, of which 15 became hurricanes.became hurricanes.

Five of the seven major storms Five of the seven major storms hit the US, including Katrina.hit the US, including Katrina.