Regarding:
>>> The WW II airplane was found beneath, I think, more than two hundred feet
>>> of ice. I would think the large surface area of the plane's wings would
>>> have prevented it from exerting enough pressure on the ice to melt its
>>> way down through the ice. Assuming that's true, then the ice accumulated
>>> over the plane since it went down.
>> ...
> If the possibility of the plane melting its way through the ice or snow
is
>at issue, what would be important would not be just relative densities (as if t
he
>issue were simply buoyancy) but whether or not the plane would exert sufficient
>pressure to depress the freezing point enough to liquify the ice.
>That would depend on the plane's mass distribution & the surrounding
>temperatures. But doing the calculation is perhaps overkill since, as you note
,
>this YEC argument is one of desperation.
One thing one might want to keep in mind here is the order of magnitude of
the freezing point depression of water--which happens to be about only
0.0075 deg C/atm. This means that a local pressure in excess of 130 atm is
necessary to depress the freezing point by only 1 deg C. An even lower
freezing point requires a correspondingly proportionate pressure increase.
Even with the realization that snow is mostly air pockets rather than
solid ice, and even with the realization that various sharp parts on the
underside of the plane would initially locally exert much greater
pressures than other parts, I suspect that any significant melting that
would occur because of the introduction of the airplane into the
environment would be nearly completely a result of the released energy
upon impact from the energy of the crash itself, and and maybe from any
burning fuel. It seems to me that the *crash* of the airplane would be
sufficiently energetic for at least parts of the plane to be relatively
deeply burrowed into a preexistent field of snow.
Another thing to keep in mind is that it takes a lot of initial surface
snow to eventually wind up much later as a thin deep pack ice layer.
Another thing to bear in mind is that the ice accumulation proccess
that would happen around an inhomogeneous obstruction like an airplane
would be expected to be modified to a large degree by the plane's
presence compared to the accumulation process out in more open spaces.
Any calculation of the depth of burial relative to the time since the
plane crash would need to at least account for some of these other
processes that would be expected to swamp any static pressure-induced
freezing point depression effect. In any event, I agree with George's
assessment that "doing the calculation is perhaps overkill since, ...
this YEC argument is one of desperation".
David Bowman
David_Bowman@georgetowncollege.edu
This archive was generated by hypermail 2b29 : Mon Jan 15 2001 - 09:36:16 EST