Ocean CurrentsOcean Currents

By: Cathy Jones, Beth Kuhns, and Christine Pettit

Ocean Ocean CurrentsCurrents

• Ocean currents = organized flows that persist over Ocean currents = organized flows that persist over some geographical region and over some time some geographical region and over some time period such that water is transported from one part period such that water is transported from one part of the ocean to another part of the ocean.of the ocean to another part of the ocean.

• There are two types:There are two types:- Surface Currents--Surface Circulation- Surface Currents--Surface Circulation- Deep Water Currents--Thermohaline Circulation - Deep Water Currents--Thermohaline Circulation

Surface Currents--Surface Surface Currents--Surface CirculationCirculation

• Surface currents develop from friction between Surface currents develop from friction between the ocean and the wind that blow across the the ocean and the wind that blow across the surfacesurface

• These waters make up about 10% of all the water These waters make up about 10% of all the water in the ocean.in the ocean.

• These waters are the upper 400 meters of the These waters are the upper 400 meters of the ocean.ocean.

Examples of Warm and Cold Examples of Warm and Cold CurrentsCurrents

Warm CurrentsWarm Currents

- Gulf StreamGulf Stream

- North Equatorial North Equatorial CurrentCurrent

- South Equatorial South Equatorial CurrentCurrent

- Brazil CurrentBrazil Current

- Agulhas CurrentAgulhas Current

- California CurrentCalifornia Current

Cold CurrentsCold Currents

- North Atlantic CurrentNorth Atlantic Current- Alaska CurrentAlaska Current- Peru CurrentPeru Current- Falkland CurrentFalkland Current- Oyashio CurrentOyashio Current- Benguela CurrentBenguela Current

Deep Water CurrentsDeep Water Currents----Thermohaline Thermohaline CirculationCirculation

• These waters make up the other 90% of These waters make up the other 90% of the oceanthe ocean

• These waters move around the ocean These waters move around the ocean basins by density driven forces and gravity.basins by density driven forces and gravity.

• The density difference is a function of The density difference is a function of different temperatures and salinitydifferent temperatures and salinity

• These deep waters sink into the deep These deep waters sink into the deep ocean basins at high latitudes where the ocean basins at high latitudes where the temperatures are cold enough to cause the temperatures are cold enough to cause the density to increase.density to increase.

• Deep water circulation runs the "conveyor Deep water circulation runs the "conveyor belt" that moves warm water away from belt" that moves warm water away from the equator and cold water away from the the equator and cold water away from the poles. poles.

Currents Effects on ClimateCurrents Effects on Climate

• Currents from low latitudes into Currents from low latitudes into higher latitudes (warm currents) higher latitudes (warm currents) transfer heat from warmer to cooler transfer heat from warmer to cooler areasareas

• Influence of cold currents is most Influence of cold currents is most pronounced in the tropics or during pronounced in the tropics or during the summer months in the middle the summer months in the middle latitudeslatitudes

Coriolis EffectCoriolis Effect

• Since the globe is rotating, any Since the globe is rotating, any movement on the Northern movement on the Northern hemisphere is diverted to the right, if hemisphere is diverted to the right, if we look at it from our own position we look at it from our own position on the ground. on the ground.

•The Coriolis effect has great The Coriolis effect has great significance in astrophysics significance in astrophysics and stellar dynamics, in and stellar dynamics, in which it is a controlling factor which it is a controlling factor in the directions of rotation of in the directions of rotation of sunspots.sunspots.

• It is also significant in the earth It is also significant in the earth sciences, especially meteorology, sciences, especially meteorology, physical geology, and oceanography, physical geology, and oceanography, in that the Earth is a rotating frame in that the Earth is a rotating frame of reference, and motions over the of reference, and motions over the surface of the Earth are subject to surface of the Earth are subject to acceleration from the force indicated. acceleration from the force indicated.

• The Coriolis effect The Coriolis effect is most apparent in is most apparent in the path of an the path of an object moving object moving longitudinally. On longitudinally. On the Earth an object the Earth an object that moves along a that moves along a north-south path, north-south path, or longitudinal line, or longitudinal line, will undergo will undergo apparent deflection apparent deflection to the right in the to the right in the Northern Northern Hemisphere and to Hemisphere and to the left in the the left in the Southern Southern Hemisphere. Hemisphere.

• The Coriolis deflection is therefore The Coriolis deflection is therefore related to the motion of the object, related to the motion of the object, the motion of the Earth, and the the motion of the Earth, and the latitude. For this reason, the latitude. For this reason, the magnitude of the effect is given by 2 magnitude of the effect is given by 2 sin , in which is the velocity of the sin , in which is the velocity of the object, is the angular velocity of the object, is the angular velocity of the Earth, and is the latitude.Earth, and is the latitude.

• Thus, the Coriolis force figures Thus, the Coriolis force figures prominently in studies of the prominently in studies of the dynamics of the atmosphere, in dynamics of the atmosphere, in which it affects prevailing winds and which it affects prevailing winds and the rotation of storms, and in the the rotation of storms, and in the hydrosphere, in which it affects the hydrosphere, in which it affects the rotation of the oceanic currentsrotation of the oceanic currents

BiomesBiomes

• There are 5 major biomes: There are 5 major biomes: 1.1. AquaticAquatic2.2. DesertsDeserts3.3. ForestsForests4.4. GrasslandsGrasslands5.5. TundraTundra

Because of the Coriolis Effect and Ocean Currents, the planet has biomes

AquaticAquatic

• Water is the common link Water is the common link among the five biomes and among the five biomes and it makes up the largest it makes up the largest part of the biosphere, part of the biosphere, covering nearly 75% of the covering nearly 75% of the Earth’s surface. Aquatic Earth’s surface. Aquatic regions house numerous regions house numerous species of plants and species of plants and animals, both large and animals, both large and small. In fact, this is where small. In fact, this is where life began billions of years life began billions of years ago when amino acids first ago when amino acids first started to come together. started to come together. Without water, most life Without water, most life forms would be unable to forms would be unable to sustain themselves sustain themselves

• The aquatic biome can be The aquatic biome can be broken down into two basic broken down into two basic regions, freshwater (i.e, regions, freshwater (i.e, ponds and rivers) and ponds and rivers) and marine (i.e, oceans and marine (i.e, oceans and estuaries). estuaries).

DesertsDeserts• Deserts cover about one Deserts cover about one

fifth of the Earth’s surface fifth of the Earth’s surface and occur where rainfall is and occur where rainfall is less than 50 cm/year. less than 50 cm/year. Although most deserts, Although most deserts, such as the Sahara of such as the Sahara of North Africa and the North Africa and the deserts of the deserts of the southwestern U.S., Mexico, southwestern U.S., Mexico, and Australia, occur at low and Australia, occur at low latitudes, another kind of latitudes, another kind of desert, cold deserts, occur desert, cold deserts, occur in the basin and range in the basin and range area of Utah and Nevada area of Utah and Nevada and in parts of western and in parts of western Asia. Most deserts have a Asia. Most deserts have a considerable amount of considerable amount of specialized vegetation, as specialized vegetation, as well as specialized well as specialized vertebrate and vertebrate and invertebrate animals.invertebrate animals.

ForestsForests• Today, forests occupy Today, forests occupy

approximately one-third approximately one-third of Earth’s land area, of Earth’s land area, account for over two-account for over two-thirds of the leaf area of thirds of the leaf area of land plants, and contain land plants, and contain about 70% of carbon about 70% of carbon present in living things. present in living things.

• Present-day forest biomes, Present-day forest biomes, biological communities that biological communities that are dominated by trees and are dominated by trees and other woody vegetation can other woody vegetation can be classified according to be classified according to numerous characteristics, numerous characteristics, with seasonality being the with seasonality being the most widely used. Distinct most widely used. Distinct forest types also occur forest types also occur within each of these broad within each of these broad groups.groups.There are three major types There are three major types of forests, classed of forests, classed according to latitude: according to latitude:

• tropical tropical • temperate temperate • boreal forests (taiga) boreal forests (taiga)

GrasslandsGrasslands

• Grasslands are Grasslands are characterized as lands characterized as lands dominated by grasses dominated by grasses rather than large rather than large shrubs or trees. shrubs or trees.

• There are two main There are two main divisions of divisions of grasslands: (1) tropical grasslands: (1) tropical grasslands, called grasslands, called savannas, and (2) savannas, and (2) temperate grasslands temperate grasslands

TundraTundra

• Characteristics of TundraCharacteristics of Tundra

• Extremely cold climate Extremely cold climate

• Low biotic diversity Low biotic diversity

• Simple vegetation structure Simple vegetation structure

• Limitation of drainage Limitation of drainage

• Short season of growth and reproduction Short season of growth and reproduction

• Energy and nutrients in the form of dead organic Energy and nutrients in the form of dead organic material material

Work ConsultedWork Consulted

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