("greenwavepilot" wrote)

snip
Michael, I am training in a Diamond DA-20 C1, incidentally, the only
composite airplane on my flight schools ramp. I am flying in upstate
SC. This morning, at 8:15 the top surfaces of the wings on the C1 were
iced significantly, as was the nose and fuselage (tail boom). Outside
air temp was 41*F/Overnight low was 40*F. Plane is tied-down, morning
sun was directly on wing surfaces, no intervening shadows. My lesson
was delayed, of course.


There can be a thermal "dip" right before sunrise, right about at wingtip
height. Duck hunters and deer hunters will confirm (and curse) this
temperature phenomenon - forget what it's called.

41F overnight? 40F at 8:15? And still ice?

So it either go down to 32F at or near your wing, or it was below 32F a
number of feet, maybe many, many feet above your wing? Or your wing was 32F
at some point in the early morning? Wonder what it was?

Also wonder what the height of the temp reading instrument is?

Our local airport can report 40F with an overnight low of 36F yet there will
sometimes be "white-ice-dew" on the grass those mornings - usually in the
fall. We keep track of this because of our flower garden and outside plants.
Minnesota flowers in late October are a night-by-night proposition. Ooh,
there go the Impatiens.

Our airport's automated weather reporting station is less than two miles
away. Plus geologically, we are all at an identical elevation sharing the
same glacially flat sandy river bottom. This area was all sod farms just a
few years back - no other farming is sustainable in this area. Anyway, we
usually always agree with the airport temps - here at home, in the car,
neighbors thermometer, etc.

37F-40F and frost on the grass in the morning is common here.


Montblack