I'm really into ice this winter-

Sarah, John & Dylan delight in cracking the thin layers of ice that seem
to magically form on the edges of the  driveway each night, especially
as the ice is not really adhered to the asphalt and is hollow and cracks
with a satisfying pop
, I'm supposing it has something to do w/ the thermal mass qualities ie
that the driveway continues to lose heat for much of the night actually
keeping a very thin layer of water in contact with the surface from
freezing  - as I explained to them I remember my brother and I were
incapable of walking to school without cracking the ice on every puddle
wee encountered-
Evidently, water continues to seep out of the snowbanks @ the driveway
each night and freeze.
I'm thinking that the snow exposed to the sun- even on a day like
yesterday when the temp never got above 20 F, some melting occurs, the
water percolates down through the snow, and being insulated by the snow
drips out during the night, as opposed to the water that hits the bl;ack
driveway during the day and evaporates....

So where is this taking me...

I'm thinking that ice in the gutters and eaves is inevitable w/out some
added heat- ie heat trace cable..
no roof is perfectly insulated and even one that is well insulated will
still be subject to some melting from solar sources...
so some water will reach the gutters which will be as cold as the
outside air,- aluminum or copper sheet metal has no thermal mass
qualities- and freeze and then a little more will hit the ice, and a
little more......