George,
It is water vaporization caused by the very low pressure. Water
"boils" at 212 deg. f - at sea level. This caveat is included because
the higher you go above sea level the lower the boiling point of water
is. Water boils along the trailing edge of a boat or ship propellor if
it is rotating fast enough. The low pressure pockets flash some of the
water to steam and when the steam bubbles collapse due to the water
pressure, it is called cavitation. I have been on the throttles of a
submarine up under the ice cap and had cavitation, so it doesn't take a
great deal of heat. The most common ways to make water boil are to add
heat or lower ambient pressure.
Rand E.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ClassicVW@xxxxxxx wrote:
>
> In a message dated 12/29/1999 5:10:44 PM EST, siddim01@xxxxxxxxxxxxxxx writes:
>
> > Could it also be water vaporization? Above the wing, air pressure is
> > lower, so water "boils" at a lower temp, etc.
>
> It IS water "vapor". ( a la: clouds) It is not water "vaporization" due to
> heat. If that were true, and air over aircraft's wings were hot enough to
> "vaporize" water, we wouldn't need to de-ice them in the winter.
>
> George S.
>
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