Currents and Climate By Lindsey Harnack & Reid Harm.

Currents and ClimateCurrents and Climate

By Lindsey HarnackBy Lindsey Harnack

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Reid HarmReid Harm

CurrentsCurrents A current is a large stream A current is a large stream

of moving water that flows of moving water that flows through the oceans.through the oceans.

Currents carry water great Currents carry water great distances and some distances and some currents move water at the currents move water at the surface of the ocean, while surface of the ocean, while others move the deep others move the deep water.water.

Currents move the Sun’s Currents move the Sun’s energy from the equator to energy from the equator to the poles.the poles.

They also move cold water They also move cold water from the poles towards the from the poles towards the equator.equator.

This moderates the climate This moderates the climate of our planet.of our planet.

One Way to Explore Currents

Norwegian explorer Norwegian explorer Thor Heyerdahl Thor Heyerdahl proved his theory that proved his theory that ocean currents ocean currents influenced human influenced human migration by using a migration by using a raft that was powered raft that was powered only by wind and only by wind and ocean currents.ocean currents.

He showed that He showed that Polynesia could have Polynesia could have been settled from been settled from people migrating from people migrating from South America.South America.

The The windwind mainly drives mainly drives surface currentssurface currents, which , which affects water to the affects water to the depth of several depth of several hundred meters.hundred meters.

If Earth were not If Earth were not rotating, winds and rotating, winds and currents would only flow currents would only flow in straight lines to the in straight lines to the north and south poles.north and south poles.

This Coriolis effect This Coriolis effect causes the winds to causes the winds to curve.curve.

Surface CurrentsSurface Currents

Coriolis EffectCoriolis Effect

The Earth’s rotation The Earth’s rotation causes the winds causes the winds and currents to and currents to curve in relation to curve in relation to Earth’s surface.Earth’s surface.

In the northern In the northern hemisphere the hemisphere the Coriolis effect Coriolis effect causes the currents causes the currents to curve to the to curve to the right.right.

The Gulf StreamThe Gulf Stream The largest and most The largest and most

powerful surface current powerful surface current is the Gulf Stream in the is the Gulf Stream in the North Atlantic Ocean. North Atlantic Ocean.

It is caused by strong It is caused by strong winds from the west.winds from the west.

The Gulf Stream carries The Gulf Stream carries warm water from the Gulf warm water from the Gulf of Mexico to the of Mexico to the Caribbean Sea, then Caribbean Sea, then northward along the coast northward along the coast of the United States.of the United States.

This current keeps This current keeps Northern Europe much Northern Europe much warmer in the winter than warmer in the winter than it would otherwise be.it would otherwise be.

Ocean Current MapOcean Current Map

How Surface Currents Affect How Surface Currents Affect ClimateClimate

Climate is a pattern of Climate is a pattern of temperature and temperature and precipitation, typical precipitation, typical for an area over a long for an area over a long period of time.period of time.

Currents affect the Currents affect the climate by moving climate by moving cold and warm water cold and warm water around the globe.around the globe.

A surface current A surface current warms or cools the air warms or cools the air above it, affecting the above it, affecting the climate of the land climate of the land near the coast.near the coast.

Deep Currents Stream like movements Stream like movements

of ocean water located of ocean water located far below the surface far below the surface are calledare called deep currents. Deep Deep currents are not currents are not controlled by wind.controlled by wind.

Deep currents form in Deep currents form in parts of the ocean parts of the ocean where water density where water density increases. The density increases. The density of the ocean is affected of the ocean is affected by temperatureby temperature and and salinity.salinity.

Deep currents are caused by changes in density.

Deep Currents, continued Formation and Movement of Deep

Currents Differences in water density Differences in water density cause variations in the movement of deep cause variations in the movement of deep currents.currents.

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, continued

• 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, continued

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.