Currents and Wind Patterns:
Factors that Control Climates
and Iceland have much warmer and more moderate climates than would be
expected just by looking at their location. Their latitude is similar
to that of northern Canada, Labrador and Alaska, which experience a very
different climate. Why?
key to this puzzle lies in understanding the power of the wind over the
vast, flat areas of ocean.
and the Effect of the Earth Spinning
Over 70 % of the Earth's surface is covered with water. Wind helps this
water to move and circulate. Wind powered surface currents move the majority
of water from one place in the ocean to another. Surface currents which
originate near the equator are warm and those that originate closer to
the poles are cold currents.
An apparent force that as a result of the earth's
rotation deflects moving objects (as projectiles or air currents)
to the right in the northern hemisphere and to the left in the southern
credit US Navy Oceanographic office
cold and warm currents are constantly moving and mixing. The Coriolis
force causes currents in the open ocean north of the equator to move in
a clockwise direction while currents south of the equator move in a counterclockwise
direction. Study the map to see if you agree.
To better understand this phenomenon picture a spinning globe. Now picture
pouring a glass of water down one side of the spinning globe. What pattern
of water would you see when you stop spinning the globe? What would the
pattern look like if you turned the globe upside down and repeated the
addition to the Coriolis Effect, land masses or continents can influence
ocean currents by causing them to be deflected from their original path.
Study the map of ocean currents to see how the currents change directions
as they are deflected from land masses.
Surface currents have a considerable effect on the climate of areas along
their path. What can you learn from the map that would explain this phenomenon?
You can make a model to explore wind-driven surface currents. With this
model you can experiment with winds and currents and think about their
affect on climate around the world. How would you design it to include
some of the factors we learned about above (Coriolis effect and continent
and landmass effects)?
- 9 x 12
inch aluminum pan
straw (the kind that’s bendable)
piece of aluminum foil for rafts
the clay make continents along both sides of the aluminum pan.
the middle section of the pan with water.
- Make 3
or 4 tiny rafts (approximately 1 cm square) out of the piece of aluminum
your rafts in the “ocean.”
the straw and place the long end of the straw (end furthest from the
bend) in your mouth. Aim the short end of the straw at your “ocean”
and blow gently causing a breeze. You do not need to blow hard enough
to have a visible movement of the water. A current should begin to form.
the path of the rafts and record your observations.
the process blowing in different directions. Record your observations
in your journals.
- EXTRA: Re-design
your clay model to see what might happen when a continent is surrounded
by ocean (like in Australia and New Zealand).
- What factors
influenced the path of the rafts?
that your model could show the effects (Coriolis) of the spinning Earth.
How do you think this would affect your patterns?
- How did
the path differ when the winds blew in different directions?
- Now can
you answer this question?:
"England and Iceland have much warmer and more moderate climates
than would be expected just by looking at their location. Their latitude
is similar to that of northern Canada, Labrador and Alaska, which experience
a very different climate. Why are they warmer?"
from SCiC Oceans
and Jet Streams.
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