The rotation of the Earth affects
the outer portions of the Earth. The effect on the oceans is a steady
and continuous reaction, which causes the general direction of the ocean's
motion. This is called the Coriolis Motion, whereby water is deflected
to the right in the Northern Hemisphere and deflected to the left in the
Southern Hemisphere, as shown on the diagram above.
The Coriolis Motion is named after the French
mathematician, Gustave Gaspard Coriolis (1792-1843). The Coriolis
Motion is a visible effect of the Coriolis Force caused by a rotating sphere.
In the Northern hemisphere the wind tends to rotate counterclockwise (as
seen from above) as it approaches a low pressure area. In the Southern
hemisphere the wind rotates clockwise around pressure areas.
It is also referred to as the Coriolis Effect,
which refers to the changing motion dependent from where you look.
An example that you can use to illustrate this is that when a ball is thrown
to someone from a merry-go-round the ball moves in a straight line but
because the merry go round is moving, the ball appears to travel in a curved
path if you are looking above.
The Coriolis Motion is a difficult phenomena
to fully understand, but it is important for children to realize the influence
of a rotating sphere on the motion in the ocean.
- It is a wise old tale that
states that toilets flush to the right in the northern hemisphere and to
the left in the southern hemisphere. Theoretically there should
be some influence on the water, but the shape of the bowl and where
the water emerges influences the movement more. This tale should
be easy to test. Before you start your discussion on the movement of the
oceans, have students go home and look at what direction their toilet bowls
flush. If there is more than one bathroom, have them record whether the
bowl is facing east, south, west, or north. Remind students not to waste
- Have students record the results as
a homework assignment and then tabulate the results on the board in the