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To study weather system we could just
use observation of the real world.
We could also use theory to understand the underlying
dynamics.
Or we could use the rotating tank
as a bridge between the observation and the theory.
The Weather in a Tank project was
designed to teach students the essence of important weather
and climate phenomena.
The rotating tank apparatus is made of a rotating table, which
rotates in a variable speed according to the phenomena we
want to study.
And the tank of water representing the fluid,
like the atmospheric fluid, rotating on the earth.
We have a view from a co-rotating camera, which
is viewing the tank like cats sitting on earth viewing
the weather phenomena.
One might wonder how much rotation affects
the behavior of, [? say, ?] weather system or eddies
in the ocean.
To illustrate this, we are playing with two experiments.
One tank of still water, not rotated.
And one tank of water who is rotating on our apparatus.
Here we have tank of still water.
We're going to disturb it by using my hand.
Imagine this is like a disturbance in the atmosphere
or wind blowing over the ocean.
Disturb it lightly by going in and out.
And I'm introducing a few blobs of dye
to see how the water is actually moving.
So they can see the fluid spreading
in all direction, both horizontally and vertically
and intermingled.
Here we have a similar tank, but it's not rotating.
And we have a view from the lab and the view
from the co-rotating camera, which
is up here on this TV monitor.
Let's disturb this water again in the same manner as before,
simulating like wind blowing over the ocean or a disturbance
in the atmosphere.
Look at the movement of the dye in this rotating system.
You notice curtains of dye forming.
It's not going in all direction.
It's creating pattern in two dimension.
If you look at the view in the co-rotating camera,
you have swirling motion with organized streaks
of dye, red and green.
This shows two-dimensional turbulence motion, which
observe on all rotating system.
It's particularly evident on Jupiter,
which is fast-rotating planet.
And the swirl here of red is very much reminiscent
of the red spot on Jupiter.
In the real world, air movement are generated
by temperature difference.
Here, we have another tank rotating,
but with a can of ice in the middle.
The ice in the middle represents the pole.
The outside of the can is at room temperature
and represents the equator.
From our everyday experience we could
imagine that cold water sinks near the can of ice
and warm water will rise on the outside.
As before, we notice the dye falling in organized pattern,
like curtains.
But on the surface, we'll see movement.
By doing this experiment on the rotating system,
we notice a much more turbulent motion
with warm water going towards the can and cold water
coming out in an organized path and very similar
to weather system.
The rotating tank has been proved
very successful in the teaching of weather and climate
here at MIT and other universities.
And students love playing with the water
and get their hand wet.