Day 1: Meshing Science and Pedagogy
The last two demonstrations were performed before a live audience of high school students. This was a team demonstration of the general circulation of the earth’s atmosphere from Noboru Nakamura and John Marshall. Noboru introduced the rotating tank to the students, explaining that it is a laboratory model of the earth’s atmosphere. The center bucket (North-pole) was filled with ice-water, and the outer edge was at room-temperature (equator).
John Showed the “null-experiment” in the smaller rotating tank, where the table was rotating, but the center bucket was at the same temperature as the rest of the tank. He asked the students what they thought would happen to drops of dyed water if he was to add it to the tank. They astutely suggested that it would just rotate around in the tank, tracing a circle. John performed to experiment, pointing out that the prediction was correct, and that from the point of view of the camera, which was in the rotating reference frame, the dye was stationary.
Noboru then demonstrated the same experiment with the bucket in the center filled with ice. Red dye was dropped in the outer portion of the annulus and blue dye was placed in the inner portion. The temperature difference across the rotating annulus generates baroclinic instability, the resulting in striking swirling of the red and blue dyes. The red dye was compared to warm air, and the blue dye to cold air; this demonstration shows the equator to pole transport of heat.
In addition to these demos, the participants interacted among themselves and inprovised a few variants of well-known experiments (Taylor columns, cylinder collapse, Karman vortices, etc.).
The last session of Day 1 started with Claudia Cenedese's talk on self-propagated and advected vortices, motivated by observations of Mediterranean eddies (Meddies) colliding with islands. Atmospheric eddies colliding with Greenland may be dynamically similar. The laboratory experiment consisted of an ice-cube generated vortex (after Whitehead et al. 1990). It was found that a self propagating vortex requires a sloping bottom to simulate the beta effect, whereas the advected vortex required moving the sea mound (island) relative to the flow using a robotic arm. It takes at least 10 weeks of work for a graduate student to produce results substantial for publication. Accordingly, the project must be simple enough to require only minimal setup time.