Ocean Currents - Thermohaline Currents (Thermo- heat, Haline-salt)
Supplies: two different glasses of dyed tap-water, two small dishes of salt, a small fish tank with tapwater in it, two stirrers.
Procedure: Take the two glasses of dyed water and pour the salt into each one of them (same amount
of salt so may need to measure!). Stir the salt until one of them dissolves. * Pour the one that didn't
dissolve fully, slowly into the fish tank. look how it creates a small current with the water.
*Why didn't the other dissolve? Because it has the same amount of salt but with more water.
Information: Ocean Currents is the steady flow of ocean water towards a specific direction.
There are four main reasons that cause Ocean Currents. The first is the amount of salt present. As the
salt changes at a different place, the density of sea water also changes from place to place, created
from the water flows of high to low density. The second is heating, when the sun falls on the surface of
the sea water at different angles it created convection currents in the water. The third one is by the
blowing of the winds on the sea surface. And the last one is the rotation of the earth on its axis, as the
earth rotates, the water rotates along with the earth.
Why is there salt present in the sea water? A mixture of salty substances that are washed out of the
rocks are deposited from the rivers into the sea. (As rain falls, it gradually dissolves the minerals. The
dissolved salts slowly enter the river and are carried down to the sea.)
So what happens when two different motions of water clash? We call those Eddies. Eddies are a
movement of water that is created from an obstacle(in this case two different current movements) to
make a whirlpool. Some Eddies are so small it's unrecognizable on the surface, while others are clashed
so hard that the Eddies show a little crevice shape in the water. How long the Eddies are there depends
upon the ocean current and the weather. Some are there for a month or so while others stay for a little
more than a year, determined by Earth's rotation and the Coriolis effect. Not all Eddies are the same,
Eddies with cold centers are called cyclonic eddy. Eddies with warm centers is called anti-cyclonic eddy.
The cyclonic eddies are found in the warm waters, while the anti-cyclonic Eddies are found in cold
waters (mostly near land).
Definitions:
Density: how compact a substance is
Convection Currents: expansion of a liquid, solid, or gas as the temp. rises, they rise in the atmosphere
above warm landmasses or seas, also shows how sea breezes and the land breezes are formed.
Coriolis effect: Where objects in the northern hemisphere are deflected to the right, and the objects in
southern hemisphere are deflected to the left. This forces the winds to shift towards the right or the
left. This effect can cause winds to blow back up to the pressure gradient.
Pressure gradient: force which is when there is a difference in pressure across a surface.
Other Procedures: You could create procedures on how the other ocean currents form. A few
examples are to put water in a jar and tilt it slightly like how the earths axis is and keep tilting. The
earth makes a full complete cycle every 24 hours, so the current is ever-changing. Another way is to
have salt on the bottom and let the salt sink to the bottom of the tank (most likely it'll look like it
disappeared), then have a really how lamp or a candle next to the tank and let it sit there until the
water starts to move. Another way is to just blow on the water and you'll see a current form.
Conclusion: The student have now learned how ocean currents work and are now able to describe
different types of ocean currents. Ocean currents are so important because it's how we regulate the
water, determine global warming, and determine in what general area the creatures of the sea live in.