This image is of a 'rimed-dendritic' irregular crystal. This crystal
form has been hard to image because of its 3 dimensional nature.
These crystals are sometimes indicative of temperature inversion layers
in the atmosphere. Although difficult to see in 2 dimensions,
it appears that the dendrites are 'cupped' up and around the rimed mass.
One thought is that the dendrites act as breaks in turbulent flow which
cause rotor-eddying and deposition of supercooled water droplets into
the center of the cup.
