Earth’s OceanEarth’s Ocean

Mrs. Harsh 6Mrs. Harsh 6thth Grade Earth Sci. Grade Earth Sci.

Facts about the OceanFacts about the Ocean

71% of earth’s surface is covered by water.71% of earth’s surface is covered by water. 5 main oceans.5 main oceans.

– Largest ocean: Pacific OceanLargest ocean: Pacific Ocean Second largest: Atlantic OceanSecond largest: Atlantic Ocean Smallest: Arctic OceanSmallest: Arctic Ocean

Terms Sea and Ocean are interchangeable.Terms Sea and Ocean are interchangeable. Parts of the global ocean that are partly surrounded Parts of the global ocean that are partly surrounded

by land are known as seas.by land are known as seas.

Characteristics of Ocean WaterCharacteristics of Ocean Water

Not safe to drink!Not safe to drink! Most salt in ocean = sodium chloride (same Most salt in ocean = sodium chloride (same

kind we put on food)kind we put on food) Salt has been added for millions of years.Salt has been added for millions of years.

As water flows toward oceans, it dissolves As water flows toward oceans, it dissolves minerals on land. Running water carries minerals on land. Running water carries dissolved minerals to the ocean.dissolved minerals to the ocean.

Water is evaporating, leaving dissolved Water is evaporating, leaving dissolved minerals behind. See Page 376 for pie chart.minerals behind. See Page 376 for pie chart.

Cool Ocean Facts:Cool Ocean Facts:

If the salt in the sea could be removed and If the salt in the sea could be removed and spread evenly over Earth's land surface it spread evenly over Earth's land surface it would form a layer more than 500 feet thick, would form a layer more than 500 feet thick, about the height of a 40-story building. about the height of a 40-story building.

Seawater is 220 times saltier than fresh lake Seawater is 220 times saltier than fresh lake water water

The weight of water is over 28.5 times The weight of water is over 28.5 times greater than the weight of salt it contains greater than the weight of salt it contains

SalinitySalinity

Oceanographers use the Oceanographers use the measure of measure of salinitysalinity to to describe the relative describe the relative amountamount of salt to water. of salt to water.

Some parts of the ocean Some parts of the ocean are saltier than others.are saltier than others.

North Atlantic ocean is the North Atlantic ocean is the saltiest.saltiest.

Climate Affects SalinityClimate Affects Salinity Coastal water in hotter, Coastal water in hotter,

dryer climates = high dryer climates = high salinity.salinity.

Water evaporates more, Water evaporates more, leaving salt behind.leaving salt behind.

lower salinity generally lower salinity generally occurs where precipitation occurs where precipitation is greater than evaporation is greater than evaporation

Water Movement Affects SalinityWater Movement Affects SalinitySome parts of the ocean move more than others.

Bays, gulfs, and seas move less than other parts.

Parts of the open ocean that do not have currents running through them can be slow moving.

Slower moving areas of water develop higher salinity.

Temperature Zones of Ocean WaterTemperature Zones of Ocean Water Temp. ↓ as depth increases.Temp. ↓ as depth increases. Heating of the ocean occurs during daylight & is warmest in Heating of the ocean occurs during daylight & is warmest in

late afternoon. More energy is absorbed when sun is high late afternoon. More energy is absorbed when sun is high in sky, and less when the sun is near horizon in sky, and less when the sun is near horizon

Water in the ocean can be divided into 3 layers by Water in the ocean can be divided into 3 layers by temperature.temperature.

Surface Zone-Surface Zone- contains less dense water, usually as a contains less dense water, usually as a result of higher temp. caused (water neutral) by warming of result of higher temp. caused (water neutral) by warming of the sun. Extensive mixing.the sun. Extensive mixing.

Thermocline Zone-Thermocline Zone- not uniform in temperature like not uniform in temperature like the Surface Zone and Deep Zones. It the Surface Zone and Deep Zones. It represents the transition between the two zones. Temp. represents the transition between the two zones. Temp. drops faster here with increased depth than other two drops faster here with increased depth than other two zones.zones.

Deep ZoneDeep Zone - The Deep Zone is the bottom layer. The - The Deep Zone is the bottom layer. The water in the Deep Zone remains cold and dense.water in the Deep Zone remains cold and dense.

Global ThermostatGlobal Thermostat

Large part of the oceans roll: absorb and Large part of the oceans roll: absorb and hold energy from sunlight.hold energy from sunlight.

The ocean absorbs and releases thermal The ocean absorbs and releases thermal energy much slower than dry land does.energy much slower than dry land does. If there were no ocean, the atmosphere could If there were no ocean, the atmosphere could

vary from 100 degrees C to -100 degrees C. vary from 100 degrees C to -100 degrees C. The rapid exchange of thermal NRG between The rapid exchange of thermal NRG between earth’s surface & atmosphere would cause earth’s surface & atmosphere would cause violent weather patterns.violent weather patterns.

Current Changes WeatherCurrent Changes Weather

Heated water near Heated water near equator causes some equator causes some coastal land to have coastal land to have warmer climates than warmer climates than they would have they would have without the currents.without the currents.

SonarSonar: Sound Navigation and : Sound Navigation and RangingRanging

Based on the echo-ranging behavior of bats.Based on the echo-ranging behavior of bats. Used to determine the ocean’s depth by Used to determine the ocean’s depth by

sending sound pulses from the ship to the sending sound pulses from the ship to the ocean floor.ocean floor.

The deeper the water, the longer the pulses The deeper the water, the longer the pulses take to return to the ship.take to return to the ship.

Scientists then calculate the distance by Scientists then calculate the distance by multiplying ½ the travel time by the speed of multiplying ½ the travel time by the speed of sound in water (1500 m/s).sound in water (1500 m/s).

Oceanography Oceanography via Satelitevia Satelite

Satellites send images back to earth that allow Satellites send images back to earth that allow scientists to measure the direction and speed of scientists to measure the direction and speed of ocean currents.ocean currents.

Satellite oceanography is one of the rapidly Satellite oceanography is one of the rapidly growing fields in modern oceanography, and it has growing fields in modern oceanography, and it has an expanding role in all areas of ocean and an expanding role in all areas of ocean and climate research. New sensors are under climate research. New sensors are under development to measure salinity and velocity, and development to measure salinity and velocity, and new analysis techniques are being developed to new analysis techniques are being developed to better interpret existing measurements. better interpret existing measurements.

Ocean CurrentsOcean Currents

A movement of ocean water that follows a regular pattern.A movement of ocean water that follows a regular pattern. Surface currents: a horizontal movement of ocean water that is Surface currents: a horizontal movement of ocean water that is

caused by wind and that occurs at or near the ocean’s surface.caused by wind and that occurs at or near the ocean’s surface. Can reach depths of several hundred meters & lengths of Can reach depths of several hundred meters & lengths of

thousands of km. thousands of km. Gulf Stream transports water 25 x’s more water than all the rivers Gulf Stream transports water 25 x’s more water than all the rivers

in the world.in the world. Controlled by: global winds, Coriolis effect, & continental Controlled by: global winds, Coriolis effect, & continental

deflections.deflections.

CompareCompareRivers & Surface CurrentsRivers & Surface Currents

Both are long & moving bodies of water.Both are long & moving bodies of water. Rivers flow because of the pull of gravityRivers flow because of the pull of gravity Surface currents are driven by wind and the Surface currents are driven by wind and the

rotation of the earth.rotation of the earth.

Surface currents make up about 10% of all the Surface currents make up about 10% of all the water in the ocean. Surface currents are water in the ocean. Surface currents are generally restricted to the upper 400 m generally restricted to the upper 400 m (1,300 ft) of the ocean. (1,300 ft) of the ocean.

Device used to measure ocean currents.Device used to measure ocean currents.

Global WindsGlobal Winds

Winds that blow across the Earth’s surface Winds that blow across the Earth’s surface create surface currents in the ocean.create surface currents in the ocean.

Near the equator, winds blow from East to Near the equator, winds blow from East to West but near the poles, ocean water is West but near the poles, ocean water is blown west to east.blown west to east.

Ships use this information to travel more Ships use this information to travel more quickly back and forth across the ocean.quickly back and forth across the ocean.

Coriolis EffectCoriolis Effect

The apparent curving of the path of a The apparent curving of the path of a moving object from an otherwise straight moving object from an otherwise straight path due to the Earth’s rotation.path due to the Earth’s rotation.

Causes surface currents in the Northern Causes surface currents in the Northern Hemisphere to turn clockwise, and surface Hemisphere to turn clockwise, and surface currents in the Southern Hemisphere to turn currents in the Southern Hemisphere to turn counterclockwise.counterclockwise.

See Page 419 figure 6 for visual.See Page 419 figure 6 for visual.

Continental DeflectionsContinental Deflections

If the earth was covered w/ water, surface If the earth was covered w/ water, surface currents would travel freely across the currents would travel freely across the globe.globe.

When surface currents meet continents, the When surface currents meet continents, the currents deflect, or change direction.currents deflect, or change direction.

Deep CurrentsDeep Currents

Streamlike movements of ocean water Streamlike movements of ocean water located far below the surface.located far below the surface.

Deep currents are not controlled by wind.Deep currents are not controlled by wind. Form in parts of the ocean where water Form in parts of the ocean where water

density increases.density increases.– Density is affected by salinity and temperature.Density is affected by salinity and temperature.

Increasing salinity and decreasing of temp. increases Increasing salinity and decreasing of temp. increases the water’s density.the water’s density.

Deep Currents FlowDeep Currents Flow

Differences in density determines the depth of the Differences in density determines the depth of the current. current.

Currents can flow directly toward each other and Currents can flow directly toward each other and on top of each other due to the different levels of on top of each other due to the different levels of density.density.– Cooler water is more denseCooler water is more dense– Dissolved solids are squeezed out of the ice & enter the Dissolved solids are squeezed out of the ice & enter the

liquid water below the ice causing salinity to increase = liquid water below the ice causing salinity to increase = increased densityincreased density

– Evaporation increases salinity = higher density.Evaporation increases salinity = higher density.

Surface Currents Affect ClimateSurface Currents Affect Climate

Warm Water Current: Create warmer climates Warm Water Current: Create warmer climates in coastal areas that would otherwise be in coastal areas that would otherwise be much colder.much colder.

Cold water surface currents: California current Cold water surface currents: California current carries water toward Mexico & keeps Cal. carries water toward Mexico & keeps Cal. Cooler than inland climate year round.Cooler than inland climate year round.

California Cold CurrentsCalifornia Cold Currents

Upwelling Brings Cold Water Up From BelowUpwelling Brings Cold Water Up From Below California’s beaches have cold water coming from the north, but they also have California’s beaches have cold water coming from the north, but they also have

cold water coming from its own depths. Water at the surface gets more sunlight cold water coming from its own depths. Water at the surface gets more sunlight than water deeper down. Thus, water is warmer at the surface and colder at depth. than water deeper down. Thus, water is warmer at the surface and colder at depth. Upwelling is the movement of deep cold waters coming to the top and is caused by Upwelling is the movement of deep cold waters coming to the top and is caused by wind. When wind blows parallel to a coastline, as it does off the California coast, it wind. When wind blows parallel to a coastline, as it does off the California coast, it can move water at a right angle to the direction the wind is blowing. This can move water at a right angle to the direction the wind is blowing. This movement is aided by movement is aided by the the CoriolisCoriolis effect effect. So, as water at the surface is being pushed . So, as water at the surface is being pushed away from the coast, water is drawn from below to replace it. That is, cold chilly away from the coast, water is drawn from below to replace it. That is, cold chilly water coming to the surface.water coming to the surface.

Upwelling Brings Cold Water Up From BelowUpwelling Brings Cold Water Up From Below

California’s beaches have cold water coming from the north, but they also have cold California’s beaches have cold water coming from the north, but they also have cold water coming from its own depths. Water at the surface gets more sunlight than water water coming from its own depths. Water at the surface gets more sunlight than water deeper down. Thus, water is warmer at the surface and colder at depth. Upwelling is the deeper down. Thus, water is warmer at the surface and colder at depth. Upwelling is the movement of deep cold waters coming to the top and is caused by wind. When wind movement of deep cold waters coming to the top and is caused by wind. When wind blows parallel to a coastline, as it does off the California coast, it can move water at a blows parallel to a coastline, as it does off the California coast, it can move water at a right angle to the direction the wind is blowing. This movement is aided by right angle to the direction the wind is blowing. This movement is aided by the the CoriolisCoriolis effect effect. So, as water at the surface is being pushed away from the coast, water is drawn . So, as water at the surface is being pushed away from the coast, water is drawn from below to replace it. That is, cold chilly water coming to the surface.from below to replace it. That is, cold chilly water coming to the surface.

The Intertidal ZoneThe Intertidal Zone

Located between the low-tide and high-tide Located between the low-tide and high-tide limits.limits.

Organisms that live there must be able to Organisms that live there must be able to live in water and on exposed land.live in water and on exposed land.

Changes twice a day.Changes twice a day. Some animals attach themselves to rocks Some animals attach themselves to rocks

so they are not swept out to sea during low so they are not swept out to sea during low tide….clams, oysters, starfish.tide….clams, oysters, starfish.

TidesTides

Daily changes in the level of ocean water.Daily changes in the level of ocean water. Tides are influenced by the sun and the Tides are influenced by the sun and the

moon.moon. How often tides occur & the difference in How often tides occur & the difference in

tidal levels depend on the position of the tidal levels depend on the position of the moon as it revolves around the earth.moon as it revolves around the earth.

Moon’s pull is strongest on the part of the Moon’s pull is strongest on the part of the Earth directly facing the moon.Earth directly facing the moon.

Battle of the BulgeBattle of the Bulge When part of the ocean is directly facing the When part of the ocean is directly facing the

moon, the water there bulges toward the moon.moon, the water there bulges toward the moon. At the same time, the opposite side bulges due to At the same time, the opposite side bulges due to

the Earth’s rotation & the motion of the moon the Earth’s rotation & the motion of the moon around the earth.around the earth.

If the Earth & moon rotated at the same speed, If the Earth & moon rotated at the same speed, tides would not alternate between high and low.tides would not alternate between high and low.

Moon rotates around the earth much slower than Moon rotates around the earth much slower than the earth rotates.the earth rotates.– Spring tidesSpring tides occur when earth and moon are alligned. occur when earth and moon are alligned.

Largest daily tidal range.Largest daily tidal range. Occur at new & full moon (every 14 days)Occur at new & full moon (every 14 days)Neap TidesNeap Tides: Sun & moon are at right angles to ea. other.: Sun & moon are at right angles to ea. other.

Gravitational forces work against each other. Smallest daily Gravitational forces work against each other. Smallest daily tidal range. (P. 434)tidal range. (P. 434)

Sites used:Sites used:

http://www.theoceans.zoomshare.com/9.htmhttp://www.theoceans.zoomshare.com/9.htmll

http://aquarius.nasa.gov/education-salinity.hhttp://aquarius.nasa.gov/education-salinity.htmltml

http://marinebiologyoceanography.suite101.http://marinebiologyoceanography.suite101.com/article.cfm/why_californias_beaches_arcom/article.cfm/why_californias_beaches_are_colde_cold