Index of refraction changes in water or silicone oil can be imaged on the screen. Simply set the convection cell, filled to about a cm or 1/2 cm depth, on a view graph machine. Heat from below with a hair dryer or heat blower gun. Patterns that form in the layer are imaged on the screen. Use shallow depth and tilted cell to show how convection cell size scales with depth. Blow on surface to produce shear that will align the convection. Compare with satellite images of atmospheric polygonal convection (but why is aspect ratio so different?)
Typical setup sketch (above) and in action (below).
Typical image on the screen:
©2000. John Hart, University of Colorado