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.
