"Doug" wrote in message
om...
This was gleaned form talking to a Phd (meteorology) instructor,
Citation, Super Cub pilot.

Water will not freeze until it is 0 C or below.
Just because it is 0 degrees or below doesn't mean water HAS to
freeze.
There is themometer error, but there are also lower pressure areas on
the wing/airframe, and due to the lower pressure, the temperature
lowers.
It is possible to get ice when your themometer reads above zero, but
it will be zero or below where the ice is.

Water to ice state transition is statistical in nature and not always
governed by group temperature.