When Whirls Collide 10/30/2015
Record your observations in your science
journal.
Procedure:
1. Fill a large tub with water 5 cm deep.
2. Add 10 drops of red food coloring to the water at one end of the
tub
3. Add 10 drops of blue food coloring to the water at the other end
of the tub.
4. Using a pencil, quickly stir the water at one end of the tub in a
clockwise direction while your partner stirs the water at the other
end in a counterclockwise direction. Stir both ends for 5 s.
5. Draw what you see happening in the tub immediately after you
stop stirring.
Think like a Scientist
 Ask a question: How will stirring in water in opposite directions
affect the water movement.
 Conduct Research: water movement, temperature, food
coloring, etc.
 Form a Hypothesis: If I stir the water in opposite directions, then
a whirlpool will form
 Test the Hypothesis with a controlled experiment:
Independent Variable- The direction of stir
Dependent Variable-The movement of the water
Constants: speed of stirring, amount of food coloring, etc…
Think like a Scientist
Continued…
 Gather Data-The drawing you created is the data you would
use.
 Analyze Results-Stirring the water did not cause a whirlpool to
form in the center of the tub.
 Draw Conclusions-Based on the data I collected, my
hypothesis is incorrect.
 Communicate Results-I communicated me results by sharing
with my classmates.
Think about it.
Draw what you see happening in the
tub immediately after I stop stirring.
How did stirring cause the blue water
and the red water interact?
Explain how this activity might relate to
how ocean currents interact
Ocean Currents
Chapter 5.1
Objective: I CAN.. Investigate the relationship between
currents and oceanic temperature differences.
Major Ocean Currents
 An Ocean Current is a
movement of ocean water
that follows a regular pattern
 Wind-driven currents are
called surface currents
 Surface currents carry warm
or cold water horizontally
across the ocean’s surface
Currents are influenced by weather,
the Earth’s rotation, and the position
of the continents.
Major Ocean Currents
 Surface currents extend to about 400 m
below the surface (less than ¼ mile), and
they move as fast as 100 km/day (60
miles)
 Earth’s major wind belts, called prevailing
winds, influence the formation of ocean
currents and the direction they move.
 The Gulf Stream is one of the longest
surface currents – it transports 25 times
more water than all the rivers of the world.
Surface Currents
 Stream-like movements of water that occur at or near the
surface of the ocean.
 Surface currents are controlled by 3 factors:
 Global Winds, the Coriolis effect and Continental Deflections.
Global Winds
Have you ever blown gently on a cup
of hot chocolate?
…Ripples move across the surface caused by a
tiny surface current created by your breath.
In much the same way that you create ripples, winds
that blow across the Earth’s surface create
SURFACE CURRENTS in the ocean.
Global Winds
o Different winds cause currents to flow in different
directions.
o Near equator – winds blow ocean east to west
o Closer to poles – winds blow ocean west to east
o Merchant ships often use these currents to travel
more quickly back and forth across the oceans.
Surface Currents
The Coriolis Effect
 The Earth’s rotation causes wind and surface
currents to move in curved paths rather than
in straight lines.
Coriolis Effect
 The Coriolis Effect is the apparent curving
of moving objects from a straight path
due to the Earth’s rotation.
 The Coriolis Effect causes surface currents
in the Northern Hemisphere to turn
clockwise, and surface currents in the
Southern Hemisphere to turn counterclockwise.
What causes currents to
move in curved paths instead
of straight lines?
the
Coriolis Effect
http://channel.nationalgeographic.co
m/channel/none-of-theabove/videos/corioliseffect/?source=searchvideo
(Ball on merry-go-round experiment 2:57)
Continental Deflections
 If the Earth’s surface were covered only with water,
surface currents would travel freely across the
globe in a uniform pattern.
 The shapes of continents and other land masses
affect the flow and speed of currents.
 Currents form small or large loops and move at
different speeds, depending on the land masses
they contact.
Continental Deflections
 Continents rise above sea level over roughly
one-third of the Earth’s surface.
 When surface currents meet continents, the
current deflect, or change direction.
Taking Temperatures
 Currents are also affected by the temperature of the water in
which they form.
 Warm-water currents begin near the equator and carry warm
water to other parts of the ocean.
 Cold-water currents begin closer to the poles and carry cool
water to other parts of the ocean.
Rip Currents
 A rip current is a narrow, powerful
surface current which flows away from
the shore.
 It is caused by pressure building up from
uneven buildup of water from waves.
 They can flow very quickly and can be
difficult to detect until you are in one.
Surface currents are
controlled by what 3 factors?
Global winds
The Coriolis Effect
Continental Deflections
All three factors work together to form a pattern
of surface currents on Earth.
Deep Currents
Stream-like movements of ocean
water far below the surface.
Deep Currents
Deep currents are not controlled by the wind. WHY?
• Deep currents form in parts of the ocean where density increases.
• Density is the amount of matter in a given space, or volume.
• Density of ocean water is affected by temperature and salinity---a measure of the amount of dissolved salts or solids in a liquid.
 Both decreasing the temperature of ocean water and
increasing the water’s salinity increase the water’s density.
Deep Currents
How Deep Currents Form
(page 128)
• Decreasing temperature
• Increasing salinity through freezing
• Increasing salinity through evaporation
• Deep currents form where the density of ocean water in
Water density depends on temperature and salinity.
Brainpop: Ocean Currents
https://www.brainpop.com/science/ea
rthsystem/oceancurrents/
Great Ocean Conveyor Belt
 The Great Ocean Conveyor Belt is the name for a
model of the large system of ocean currents that affects
weather and climate by circulating thermal energy around
Earth.
 In this model, high salinity water cools and sinks in the North
Atlantic, and deep water returns to the surface in the Indian
and Pacific Oceans through upwelling
Great Ocean Conveyor Belt
 Scientists estimate that the Great Ocean Conveyor Belt model takes
about 1,000 years to complete a cycle.
Great Ocean Conveyor Belt
http://education.nationalgeographic.c
om/education/media/ocean-currentsand-climate/?ar_a=1
Compares Ocean Conveyor to a roller coaster (2:33)
Upwelling

Upwelling is the vertical movement of water toward the
ocean’s surface.

Upwelling occurs when wind blows across the ocean’s surface
and pushes water away from an area. Deeper colder water
then rises to replace it.
 Upwelling often occurs along coastlines.
 Upwelling brings cold, nutrient-rich water
from deep in the ocean to the ocean’s
surface.
Video time
Putting it together
(1)List the three factors that cause surface
currents.
(2)List the three factors that cause deep
currents.
(3)How are surface currents and deep
currents different?
3 factors that cause Surface
Currents
(1) Global winds
(2) The Coriolis Effect
(3) Continental deflections
 These three factors keep surface currents
flowing in distinct patterns around the Earth.
3 factors that cause
Deep Currents
(1) Decreasing temperature
(2) Increasing salinity through freezing
(3) Increasing salinity through
evaporation