I might have found you a pic!
A Snowtrooper Lieutenant:(if I did This right)
http://starwars.wikia.com/wiki/File:Snowtr.jpgBut i cant find a snowtrooper captain pic
Would the snowtroopers be considered army or naval forces? naval ranks are higher than army ranks in all universes, so a naval lieutenant would be a ground captain and a naval captain would be a ground colonel (if I figured it right).
Since the Snowtroopers are supposed to be a specialized branch of Stormtroopers, I would venture to guess they are ground forces.(unlike the Galactic Marine from whom they are derived which are naval forces??)
Me being an army sergeant it makes no difference to me, I am enlisted and they are grossly overpaid IMO...
There are pics of the ranks during imperial reign, but each is slightly different. Two versions (at least) exist, early=version one and later=version two.
The pic in the link says lieutenant, but that looks like a ground forces rank and I am unable to see the cylinders beside the top color boxes.
These are the later=version two rank descriptions (because of the pic and box colors look like this version):
Two cylinders, one on each side of the top bar is a ground lieutenant.
One cylinder, on the right side of the top bar is a ground captain.
Both ranks contain two rows of two boxes atop each other, top being red and bottom being blue.
Probably didn't clear much up, but maybe we got a pic!