Transcript Ocean Currents

Ocean Currents
By: Cathy Jones, Beth Kuhns, and Christine Pettit
Ocean Currents
• Ocean currents = organized flows that persist over some
geographical region and over some time period such that
water is transported from one part of the ocean to
another part of the ocean.
• There are two types:
- Surface Currents--Surface Circulation
- Deep Water Currents--Thermohaline Circulation
Surface Currents--Surface Circulation
• Surface currents develop from friction between the
ocean and the wind that blow across the surface
• These waters make up about 10% of all the water in the
ocean.
• These waters are the upper 400 meters of the ocean.
Examples of Warm and Cold Currents
Warm Currents
Cold Currents
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Gulf Stream
North Equatorial Current
South Equatorial Current
Brazil Current
Agulhas Current
California Current
North Atlantic Current
Alaska Current
Peru Current
Falkland Current
Oyashio Current
Benguela Current
Deep Water Currents--Thermohaline
Circulation
• These waters make up the other 90% of the
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ocean
These waters move around the ocean basins by
density driven forces and gravity.
The density difference is a function of different
temperatures and salinity
These deep waters sink into the deep ocean
basins at high latitudes where the temperatures
are cold enough to cause the density to
increase.
Deep water circulation runs the "conveyor belt"
that moves warm water away from the equator
and cold water away from the poles.
Currents Effects on Climate
• Currents from low latitudes into higher
latitudes (warm currents) transfer heat
from warmer to cooler areas
• Influence of cold currents is most
pronounced in the tropics or during the
summer months in the middle latitudes
Coriolis Effect
• Since the globe is rotating, any movement
on the Northern hemisphere is diverted to
the right, if we look at it from our own
position on the ground.
• The Coriolis effect has great
significance in astrophysics and
stellar dynamics, in which it is a
controlling factor in the directions
of rotation of sunspots.
• It is also significant in the earth sciences,
especially meteorology, physical geology,
and oceanography, in that the Earth is a
rotating frame of reference, and motions
over the surface of the Earth are subject
to acceleration from the force indicated.
• The Coriolis effect is
most apparent in
the path of an
object moving
longitudinally. On
the Earth an object
that moves along a
north-south path, or
longitudinal line, will
undergo apparent
deflection to the
right in the Northern
Hemisphere and to
the left in the
Southern
Hemisphere.
• The Coriolis deflection is therefore related
to the motion of the object, the motion of
the Earth, and the latitude. For this
reason, the magnitude of the effect is
given by 2 sin , in which is the velocity of
the object, is the angular velocity of the
Earth, and is the latitude.
• Thus, the Coriolis force figures
prominently in studies of the dynamics of
the atmosphere, in which it affects
prevailing winds and the rotation of
storms, and in the hydrosphere, in which
it affects the rotation of the oceanic
currents
Biomes
Because of the
Coriolis Effect and
Ocean Currents,
the planet has
biomes
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There are 5 major biomes:
Aquatic
Deserts
Forests
Grasslands
Tundra
Aquatic
• Water is the common link
among the five biomes and it
makes up the largest part of
the biosphere, covering nearly
75% of the Earth’s surface.
Aquatic regions house
numerous species of plants
and animals, both large and
small. In fact, this is where life
began billions of years ago
when amino acids first started
to come together. Without
water, most life forms would
be unable to sustain
themselves
• The aquatic biome can be
broken down into two basic
regions, freshwater (i.e, ponds
and rivers) and marine (i.e,
oceans and estuaries).
• Deserts cover about one fifth
of the Earth’s surface and
occur where rainfall is less
than 50 cm/year. Although
most deserts, such as the
Sahara of North Africa and the
deserts of the southwestern
U.S., Mexico, and Australia,
occur at low latitudes, another
kind of desert, cold deserts,
occur in the basin and range
area of Utah and Nevada and
in parts of western Asia. Most
deserts have a considerable
amount of specialized
vegetation, as well as
specialized vertebrate and
invertebrate animals.
Deserts
Forests
• Today, forests occupy
approximately one-third
of Earth’s land area,
account for over twothirds of the leaf area of
land plants, and contain
about 70% of carbon
present in living things.
• Present-day forest biomes,
biological communities that are
dominated by trees and other
woody vegetation can be
classified according to
numerous characteristics, with
seasonality being the most
widely used. Distinct forest
types also occur within each of
these broad groups.
There are three major types of
forests, classed according to
latitude:
• tropical
• temperate
• boreal forests (taiga)
Grasslands
• Grasslands are
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characterized as lands
dominated by grasses
rather than large shrubs
or trees.
There are two main
divisions of grasslands:
(1) tropical grasslands,
called savannas, and (2)
temperate grasslands
Tundra
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Characteristics of Tundra
Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead organic material
Work Consulted
• www.webct.udayton.edu
• www.enature.com