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Location: UFOUpDatesList.Com > 2007 > Jan > Jan 11

Re: O'Hare Sighting Cloud Hole Effect - Tarbell

From: Michael Tarbell <mtarbell.nul>
Date: Wed, 10 Jan 2007 14:02:37 -0700
Fwd Date: Thu, 11 Jan 2007 07:58:10 -0500
Subject: Re: O'Hare Sighting Cloud Hole Effect - Tarbell

See below a crude estimate of the minimum energy and power
requirements for creating a droplet-free channel in a cloud via
simple heating, with application to the O'Hare case. Any and all
feedback is welcome, I am by no means an expert in cloud

It is only necessary to bring the material in the channel above
the dew point temperature in order to evaporate the droplets. We
may neglect the presence of the water itself, since even in
fully-saturated air the mass of water is a factor ~100 smaller
than the mass of air.

Assume that the cloud layer is uniform in temperature, 1 degC
below the dew point. This is not unreasonable, since, by
definition, the base of the cloud layer is precisely _at_ the
dew point, and the cloud layer thickness considered here is
fairly small.

The energy required to raise the temperature of air by 1 degC at
constant pressure is about 10^7 ergs per gram of air. Assuming a
channel diameter of 30 ft and a length of 100 ft (pending better
data), the volume of enclosed air is ~71,000 cu.ft, which
corresponds to ~2 x 10^6 gm of air. The total energy required to
"clear the channel" is thus ~2 x 10^13 ergs.

The accounts published so far are not explicit about the
timescale of the process, other than it was apparently very
rapid. If we assume a timescale of 1 sec, the required power
output is 2 x 10^13 erg/sec, or 2 megawatts. This is substantial
but not astronomical, e.g., the MIRACL chemical laser at the
White Sands Missile Range can produce continuous-wave output in
the megawatt range.

_However_, the above estimate must be considered an absolute
minimum, requiring some unknown process operating at 100%
efficiency. Heating by absorption of radiation would not be
nearly this efficient, except under highly contrived conditions
(e.g., total absorption below the dew point, total transparency
above it). By analogy, the energy expended bringing a pot of
water to a boil on the stove is substantially greater than the
product of the specific heat and the temperature change.

One might consider using specific wavelengths (e.g., microwaves)
to selectively heat the water rather than the entire air mass,
but I don't think this would substantially alter the energy
requirements: the droplets may become arbitrarily warm, but the
vast majority of the air around them is still saturated and will
not accept additional vapor. Even if the droplets were to "boil
off", the vapor thus generated would rapidly cool and recondense
in the surrounding air, until the air/vapor mixture finally
equilibrated above the dew point temperature. So the only
difference in this scenario is that the air is being heated by
interaction with hot water rather than directly. The energy
required should be virtually the same (but comments are
solicited here).

The reason I've been belaboring this cloud hole effect is that
it is a rare opportunity to put quantitative constraints on a
physical effect that, by all accounts, is definitively
associated with a multiple-witness UFO. This is a _physical_
_trace_ case, no less so than finding imprints from landing
gear. If it can be demonstrated from first principles that no
weather-related or man-made process can reproduce this effect on
this time scale, then the significance of this case will
increase immensely.


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