Transcript Oceans Moderate Climate - Mr. Slater's Science Class

Oceans Moderate Climate
By: Suzanne A. McKeon
AKA: “Sammie”
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.
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.
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.
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.
The Water Cycle
http://ga.water.usgs.gov/edu/watercycle.html
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/climate/images/seasons_cycle_big_gif_image.html
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.
The Evaporation Stage
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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.
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
The Carbon Cycle
Carbon is an element. It is part
of oceans, air, rocks, soil and all
living things. Carbon doesn’t
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/climate/images/carboncycle_jpg_image.html
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
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
Oceans Currents
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North & South Equatorial Current
Equatorial Counter Current
North Atlantic Drift
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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.
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.
Gravitational Pull
http://search.live.com/images/results.aspx?q=gravitational+pull&FORM=BIRE
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.
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.
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.
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 densitydependent currents, also known as the
thermohaline circulation.
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.
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).
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.