What it shows:
Hot fluid rises, cool fluid sinks. Here is a desktop convection cell modeling the processes in the atmosphere, oceans or stellar interiors.
How it works:
The currents are set up in rheoscopic fluid 1 (basically minute aluminum flakes in water) in a small 10×10×15cm glass tank. Half the base of the tank rests on a heater, the other on an aluminum block that acts as a heat sink. The rheoscopic fluid has a weird metallic sheen such that the bulk motion of fluid is clearly seen from the changing reflectivity.
Setting it up:
The heater is a small hotplate set at around 200W output. The aluminum block needs to be chosen to match the height of the heater (or adjusted to do so) for good thermal contact. The translucent nature of the fluid makes back lighting probably the best option - there is too much reflection off of the glass wall in front lighting. A camera setup is required - play around with the aperture to get the best contrast.
This presentation of convection currents is a preferred choice to the Thymol Blue Cell.
1 made by Kalliroscope Inc., 111 Pine Street Graham NC 27253