Transcript How do the currents on the ocean`s surface move?

Standard 5.b -- Students know the relationship between the
rotation of Earth and the circular motions of ocean currents and air
in pressure centers.
Why We Should Care:
• It helps to explain how
the weather moves
across the sky
• It explains why we
have the climate that
we do here in
California
What is a fluid?
A fluid is a substance that conforms to the container that
it is in.
Is water a fluid?
Is a brick a fluid?
Is air a fluid?
Fluids (liquids and gases) are easily influenced by other
things.
Water flows down the
slightest hill because of
gravity
Air moves out of the way
when you walk through it
Air and water both behave
in similar ways because
they are fluids.
What fluids are present on or above the surface of the
Earth?
• The ocean (water)
• The atmosphere
(air)
They are easily
influenced by other
forces
1st Factor that Affects
Air Currents -Energy from the Sun
Heat from the sun warms air enough
that it rises…but it is not the same
amount at every place on the globe.
As you move
north or south,
the same
amount of sun
gets spread
out over a
greater area,
so it is not as
warm.
•Warm air at the equator rises until it hits the stratosphere
(upper layer of atmosphere)
• It then spreads out and cools.
•Eventually, it cools enough to sink and return to Earth
•This process creates a convection current
This convection current is
called a Hadley cell and it
looks like this in its
simplest form.
But here’s the
problem…the Earth is
spinning.
2nd Factor that
Affects Air
Currents –
Spin of the Earth
Each current of air close to the Earth’s
surface deflects (turns) because the
Earth is spinning.
This is called the Coriolis effect.
In Northern
Hemisphere,
rotation is
clockwise (right)
In Southern
Hemisphere,
rotation is
counterclockwise
(left)
This process makes three separate cells in each of the
hemispheres.
Wind Type
Latitude
Direction of Air
Current
Trade Winds
0 – 30 degrees
blows west
Prevailing Westerlies
30 – 60 degrees
blows east
Polar Easterlies
60 – 90 degrees
blows west
Surface Currents
• Surface currents are movements of water that flow in a
horizontal direction on the ocean’s surface.
air flow
• The surface currents develop from friction between the
ocean and the wind that blows across the surface.
• Below are the surface currents throughout the worlds’ oceans.
• The direction of the surface currents correspond to the winds that
blow above the water
westerlies
trades
westerlies
Gyres
• Numerous surface currents work together to form large circular
patterns called gyres.
• The gyres rotate in opposite directions because of the different air
current zones that drive the surface currents
These surface currents are ultimately responsible for distributing heat
around the globe.
They move warm water from the equator toward the poles.
Standard 5.d -- Students know properties of ocean water, such as
temperature and salinity, can be used to explain the layered structure of
the oceans, the generation of horizontal and vertical ocean currents,
and the geographic distribution of marine organisms.
Why We Should
Care:
•These currents
regulate the world
temperatures…if
they shut down, we
could be thrown into
another ice age
Density currents are different from surface currents
because they move vertically rather than horizontally.
They are driven by differences in density of ocean water.
Density: how much mass a substance has in a certain
volume of space
Mass: how heavy the molecules are
Volume: how much space the molecules take up
Examples: Water has a density of 1.0 g/cm3 while lead
has a density of 11.3 g/cm3.
More dense
Less dense
more molecules in a specific
space, tends to sink
less molecules in a specific
space, tends to rise
Factors that Affect the Density of Ocean Water
1. Temperature
When water heats up,
the molecules move
faster and take up
more space.
+
+
H
Cold Water:
H
O
+
+
-
+
+
H
H
O
H
H
+
+
H
H
H
O
-
H
H
+
+
H
O
O
-
-
O
+
+
H
+
+
H
+
H
O
-
O
+
+
+
-
H
O
-
+
+
H
H
O
-
O
tightly packed
more dense
sinks
+
+
H
H
-
H
H
Warm Water:
spacious
less dense
rises
Because the Earth
is tilted, the sun’s
rays hit the Earth
differently, called
differential heating.
This causes the
density of sea
water to vary with
location.
Water at the Equator:
most direct sun
warmest
less dense
Water at the poles:
least direct sun
coolest
more dense
2. Salinity
When salt gets
dissolved in water,
more molecules are
crammed into the
same amount of space
+
+
H
+
+
H
H
+
+
spacious
less dense
rises
H
H
H
H
H
Salt Water:
-
Cl -
Na+
+
+
H
+
H
O
-
O
+
+
+
H
O
-
-
+
+
H
O
O
Fresh Water:
H
H
O
+
+
H
O
O
-
-
-
H
Na+
Cl -
tightly packed
more dense
sinks
Sea salt is actually a
mixture of many
different substances
These substances
come from two
sources:
1.Weathered rocks –
runoff breaks down
rock and carries the
sediments to the
ocean
2.Volcanic gases –
eruptions spew gases
in the air which
eventually land in the
ocean
Why is the salinity so low at the
Equator?
Lots of rain which dilutes the
ocean
Why is the salinity so high at 30° N
and S?
Lots of sun (deserts) evaporates
ocean water making it salty
Density currents create the Ocean Conveyor Belt. It is a large current system that
runs throughout the world.
It consists of:
•Warm surface flow (at the ocean surface)
•Cold subsurface flow (at the ocean floor)
The circulation current sinks in the North Atlantic because of the cold temperature
of the high latitudes (high density water)
The current rises in the Indian Ocean because of the excessive rain and in the
Pacific Ocean because the water is slightly warmer (low density water)
The warm surface flow gives much of Europe and North America a warm climate
because of warm water brought northward.
As the Earth warms, polar ice will melt making the water less dense, slowing down
the sinking process and shutting down the entire belt.
Much of the Northern Hemisphere would be thrown into an ice age.
Ice Age if Current shuts down
Ocean Layers
Name
Name
Percent
Percent
Temp
Temp
Salinity
Salinity
Density
Density
Surface
Surface
2%
2%
Warm
Warm
Low
Low
Low
Low
Transition
Transition
18%
Medium
Medium
Medium
Deep
Deep
80%
Cold
High
High
Name
Nutrients
Organisms
Surface
Poor
Transition
Transition
Medium
Phytoplankton (need light)
Zooplankton (eat phytoplankton)
Larger marine life
Deep
Deep
Rich
Decomposing organisms
Upwelling
Upwelling is a
process that
brings nutrients
from the bottom
of the ocean to
the surface.
Wind blows water
at the surface
driving it away.
This allows lower
layers to move
upward bringing
nutrients to the
surface.
Standard 7.b -- Students know the global carbon cycle: the different
physical and chemical forms of carbon in the atmosphere, oceans,
biomass, fossil fuels, and the movement of carbon among these
reservoirs.
Why We Should Care:
• We are active
participants in the
cycle
• There is debate about
how humans affect the
cycle and ultimately
the global climate
• Carbon’s
flexibility allows it
to form many
different types of
compounds,
which allows
carbon to travel
through the
different parts of
the environment
Atmosphere: The air above the Earth’s crust
Rocks: The Earth’s crust
Fossil Fuels: Substances made of once-living materials
Oceans: The water on the Earth’s crust
Biomass: All living organisms on the planet
• Primary
Carbon in
RocksForm:
– Calcium carbonate
(CaCO3)
• % of world-wide
Carbon storage:
– 99.9%
• Formed by:
– Sedimentation from the
ocean
• Recycled through:
– Volcanic eruptions to
make CO2 in the
atmosphere
Carbon in the Atmosphere
• Primary Form:
– Carbon dioxide (CO2)
• % of world-wide Carbon
storage:
– 0.001%
• Made by:
– Volcanic eruptions from rock
– Diffusion from the ocean
– Respiration from biomass (living
things)
– Combustion of fossil fuels
• Recycled
through:
– Precipitation to
make H2CO3 &
CO3 in the ocean
– Photosynthesis
to make C6H12O6
in biomass
• Primary
Forms:
Carbon in the
Ocean
– Carbonic acid (H2CO3)
• % of world-wide
Carbon storage:
– 0.08%
• Made by:
– Precipitation from the
CO2 in the atmosphere
• Recycled through:
– Diffusion to make CO2
in the atmosphere
– Sedimentation to make
CaCO3 in rocks
• Primary Forms:
Carbon as Fossil
Fuels(C) and
– Carbon/coal
methane (CH4)
• % of world-wide
Carbon storage:
– 0.009%
• Formed by:
– Decomposition of
biomass (living things)
• Recycled through:
– Combustion to make CO2
in the atmosphere
• Primary Form:
Carbon in the Biomass
– Glucose (C6H12O6)
• % of world-wide
Carbon storage:
– 0.004%
• Formed by:
– Photosynthesis of
CO2
• Recycled through:
– Respiration to make
CO2 in atmosphere
– Decomposition to
make CH4 and C in
fossil fuels
Carbon Cycle Processes
• Respiration: using O2 gas to break down C6H12O6
and releasing CO2. This is done by animals
• The opposite is called photosynthesis
C6H12O6 +
O2
air
Respiration
Converts sugar to carbon dioxide
CO2
atmosphere
• Photosynthesis:
Plants breathe in
CO2 gas and with
sunlight make
C6H12O6 and
releasing O2
Carbon Cycle Processes
• The opposite is
called respiration
Photosynthesis
CO2
atmosphere
Converts carbon dioxide to sugar
C6H12O6 +
O2
air
Atmosphere
Form = CO2
Combustion
Volcanic
Eruption
Photosynthesis
Precipitation
Rock
Fossil Fuels
Form = CaCO3
Form = CH4, C
Diffusion
Respiration
Sedimentation
Decomposition
Ocean
Biomass
Form = H2CO3, CO3
Form = C6H12O6,
C6H10O5
There are two sources of energy that drive the carbon
cycle….
The sun is an external
source of energy. It
enters the carbon cycle
when plants experience
photosynthesis.
Magma from the
Earth’s interior is an
internal source of
energy. It enters the
carbon cycle when
underground rock
melts.
Animation
• http://epa.gov/climatechange/kids/movies/ca
rbon_cycle_version2.swf