A question on Suncups

Here's a question on suncups for the snow scientists out there. I understand how they are formed but what causes the variabilty in their size at different areas. For example on my tour last week the suncups on the South and North faces at Coleman Pinnacle where about the same size although the Southern ones where softer, so aspect didn't cause much variability there. A recent trip report suggest that the suncups on the Frying pan are quite small but very large on the upper reaches of Muir.
What are the idicators you should use to determine where the smallest suncups will be, altitude?aspect , slope angle?

I'm pretty sure the difference between muir and fryingpan is traffic. Lots of skiers and hikers on muir causing variability in dirt content on the snow. Dirty snow absorbs more heat and melts faster causing the big suncups...at least that is my speculation.

i remember this discussion started by Matt Peters:

www.turns-all-year.com/skiing_snowboardi...ndex.php?topic=909.0

maybe you'll find some answers.  also, Amar A. mentioned he did extensive research on the subject.  in general, i'm curious to know too....  oh, here's a photo of suncups from last July in So. Cal. altitude: about 11k; slope angle: approx. zero.

I am seriously mystified by the whole process! Kam's pictures from 8/13 show the Muir looking radically different from the runnels, canyons, and "ablation hollows" I saw on 8/8. I am not sure of Kam and Allyson's elevation, exact location, etc., but is it possible for suncups to melt out and reform into a corn surface?
I suppose with the right combination of sunlight, wind and temperatures, any type of morphology is possible, but, how common is suncup disappearance?

Boy, that is a mystery.

Just guessing... but suncups can create their own slope angles. 

But more importantly, while camping out at Anvil Rock in July a couple years ago, I noticed that wind can really affect summer snow.   I built a small tent pit and piled up snow for a wind break.  This is not fluffy snow.  By morning, my snow made wind break was nearly gone.  The wind just evaporated it.   So, factor in the wind action, which I would guess would smooth out the surface.