Oceans Moderate Climate

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Oceans Moderate Climate

• By Suzanne A. McKeon
• AKA Sammie

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Heating the ocean

• Earth is a complex and dynamic system with a
  surface that is more ocean than land. The ocean
  interacts continually with the atmosphere, by
  exchanging, storing, and transporting matter and
  energy.
• Water bodies have a much higher heat capacity
  than land and intercept more incoming sunlight
  than land surfaces because of its greater
  transparency.

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Heat Transfer

• Wherever the Sun is perpendicular to Earth's
  surface, the most heat absorption takes place.
  Equatorial and tropical regions have a net gain
  of heat, whereas polar regions experience a net
  loss. Both air and water currents re-distribute
  heat over Earth. The Sun warms the surface of the
  ocean and land, which in turn warm the atmosphere
  from the bottom up. Wherever the atmosphere
  contacts warm water, evaporation occurs and water
  vapor and energy are transferred to the air mass.

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Heat Energy

• Ocean surface waters can store tremendous
  amounts of heat energy. This heat evaporates
  large quantities of water and warms the overlying
  atmosphere. Winds then distribute this heat
  around the globe.
• The direction of air movements and the
  temperature of the ocean water determine the
  direction storm fronts take as well as their
  intensity.

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Oceans Effects on Weather

• About 70 of the world is covered by water. 97
  of this water is in the oceans and seas. Ocean
  water moves a lot! Tides, waves, surface
  currents, and deep water circulation are all
  types of ocean water movement. The oceans have a
  major effect on the weather, and they moderate
  the world's climate.

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The Water Cycle
http//ga.water.usgs.gov/edu/watercycle.html
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The Water Cycle cont

• The Earth's water is always in circulation. It
  has been recycled for the last 3 billion years.
  This process is called the water cycle.

http//www.windows.ucar.edu/tour/link/earth/Water
/water_cycle.html
http//www.windows.ucar.edu/tour/link/earth/clima
te/images/seasons_cycle_big_gif_image.html
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Water Cycle

• The cycle starts when the sun's heat evaporates
  water from the oceans into the atmosphere to form
  clouds. When the conditions are just right, the
  clouds release water as rain or snow. Most of the
  rain falls in the oceans, but the rest falls onto
  land. Rivers and streams collect water from the
  ground and return it to the ocean so the whole
  cycle can start all over again. The water cycle
  never ends because the salty ocean water
  constantly supplies fresh water to the
  continents.

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The Evaporation Stage
http//www.windows.ucar.edu/tour/link/life/images
/coast_jpg_image.html

• One process which transfers water from the
  ground back to the atmosphere is evaporation.
  Evaporation is when water passes from a liquid
  phase to a gas phase. Rates of evaporation of
  water depend on things like the temperature,
  humidity, and wind.
• Water that is held in lakes and rivers
  evaporates directly into the atmosphere. Some of
  the water in the ground may also be returned to
  the atmosphere by way of evaporation through the
  soil surface. Of course, the ocean is the
  greatest source for water evaporated into the
  atmosphere.

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The Transpiration Stage

• Transpiration is the process by which plants
  return water to the atmosphere. After absorbing
  water from the ground, plants release water
  through their leaves. Transpiration helps plants
  stay cool, in the same way perspiration keeps
  humans and animals cool.

http//www.windows.ucar.edu/tour/link/life/images
/rosebush_Pristine_jpg_image.html
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The Carbon Cycle

• Carbon is an element. It is part of oceans, air,
  rocks, soil and all living things. Carbon doesnt
  stay in one place. It is always on the move!
• Carbon moves from the atmosphere to the oceans.
  The oceans, and other bodies of water, soak up
  some carbon from the atmosphere. Animals that
  live in the ocean use the carbon to build their
  skeletons and shells.

http//www.windows.ucar.edu/tour/link/earth/clima
te/images/carboncycle_jpg_image.html
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Circulation of the Oceans Surface water
Warm currents are noted in the color red and cold
currents are noted in the color blue.
http//www.windows.ucar.edu/tour/link/earth/Water
/images/Surface_currents_jpg_image.html
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Oceans Currents

• Two Types of Ocean Currents
• 1. Surface Currents--Surface Circulation
• 10 of all the water in the ocean.
• these waters are the upper 400 meters of the
  ocean.
• 2. Deep Water Currents--Thermohaline
  Circulation
• 90 of the ocean

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Oceans Currents

• North South Equatorial Current
• Equatorial Counter Current
• North Atlantic Drift
• Surface water movement takes place in the form of
  currents. Currents move ocean water horizontally
  at the ocean's surface. Surface currents are
  driven mainly by the wind. Other forces such as
  the Coriolis effect and the location of land
  masses do affect surface current patterns. In
  fact, huge circular patterns called current gyres
  can be seen when looking at the world's ocean
  currents.
• From the equator to middle latitudes, the
  circular motion is clockwise in the Northern
  Hemisphere and counterclockwise in the Southern
  hemisphere. Near the poles of the Earth, there is
  a tendency for the gyres to flow in the opposite
  direction. This circulation of water helps spread
  energy from the Sun. The Sun warms water at the
  equator and then water and heat are transported
  to higher latitudes.

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Ocean currents are produced by many different
things.

• Currents are made by the gravitational pull of
  the moon and sun, the prevailing winds blowing on
  the ocean surface and the unequal heating of the
  water by the rays of the sun.
• The ocean currents are also affected by the
  rotation of the earth. The general movement of
  the currents is clockwise in the Northern
  Hemisphere and counterclockwise in the Southern
  Hemisphere.

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Gravitational Pull
http//search.live.com/images/results.aspx?qgravi
tationalpullFORMBIRE
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Why do currents flow?

• Currents exist at all depths in the ocean in
  some regions, two or more currents flow in
  different directions at different depths.
  Although the current system is complex, ocean
  currents are driven by two forces the Sun and
  the rotation of the Earth.

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Deep Currents

• Currents in the deep ocean exist because of
  changes in the density of sea water occurring at
  the surface. These density changes give rise to
  specific water masses, which have well-defined
  temperature and salinity characteristics, and
  which can be traced for long distances in the
  ocean.

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Role of Water Masses

• Water masses help to transfer oxygen from the
  atmosphere into the deep ocean. The sinking water
  is very cold and contains high concentrations of
  dissolved oxygen acquired at the surface, because
  cold water can hold more oxygen than warm water.
• During their flow, they mix with "older" water
  that has been away from the surface for a longer
  time, thus ensuring that the bottom waters of the
  ocean are supplied with oxygen.

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Affects of the Sun

• The Sun affects the ocean in two ways. First, it
  heats the atmosphere, creating winds and moving
  the sea surface through friction. This tends to
  drag the water surface along as the wind blows
  over it. Although the wind strongly affects the
  surface layer, its influence does not extend much
  below about 100 meters (325 feet) in depth.

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Affects of the Sun cont

• The second effect of the Sun is to alter the
  density of the ocean surface water directly by
  changing its temperature and/or its salinity. If
  water is cooled or becomes saltier through
  evaporation, it becomes denser. This can result
  in the water column becoming unstable, setting up
  density-dependent currents, also known as the
  thermohaline circulation.

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Coriolis force

• A parcel of water at the equator is moving at
  the same speed as the Earth. If it starts to move
  north, with no friction, it is then going faster
  than the Earth beneath it. To conserve momentum
  (the product of mass and velocity), it
  consequently moves more to the east as it gets
  farther from the equator. The Coriolis force
  therefore increases away from the equator.

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Coriolis Force

• This force causes water to move to the right in
  the Northern Hemisphere and to the left in the
  Southern Hemisphere. It exists because moving
  ocean water is affected by friction with the
  Earth only at the seafloor, and because the
  eastward linear velocity of the earth decreases
  from a maximum at the equator to zero at the
  poles (the rotational velocity, however, does not
  change).

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Ekman's Theory.

• The first reasonable theory of how the wind
  affects surface currents was derived by Swedish
  oceanographer and mathematician Valfrid Ekman in
  1890. Ekman considered an infinitely wide and
  deep ocean of constant density, divided into an
  infinite number of horizontal layers.
• The top layer is affected by the wind and by
  friction with the layer below it. The second
  layer is also affected by friction at top and
  bottom, and so on. The Coriolis force also
  affects the layers because they are moving.

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