For various reasons (see bottom) I've become interested in the sensitivity
of weather to initial conditions. I was hoping any experts here could help
me with the following question:

Suppose an air parcel of about 10 km size suddenly (magically?!) changed its
density, humidity and temperature, while staying within normal atmospheric
values. (Energy and mass conservation etc. don't apply at the instant of
transformation.) How long would it take till global weather was completely
scrambled from "what would have been" so that it would have no similarity
to the unperturbed system? (Apart from seasonal variations, large scale
climate etc.)

The question can of course not be answered experimentally, but are there any
results from computer simulations pointing towards a timescale? (Just order
of magnitude).

Be warned: I've had a course in atmospheric physics, but I forgot most of
it. I'm ignorant enough to be dangerous, and educated enough to be unaware
;-)

regards,

Niels
You may contact nvj -- fys ku dk

Why do I ask? From http://1632.org :

"In May of the year 2000, a six-mile sphere, centered on Grantville, West
Virginia, was displaced in space and time to Germany and 1631. Cardinal
Richelieu is not amused. This story, by Eric Flint, is the basis for a
great deal of lively discussion on http://bar.baen.com"

One of the questions being discussed is how long after the "displacement" it
is realistic to assume major meteorological events (storms etc.) developed
as they did in the REAL 1630ies. Expert help needed!

The story itself is better than the cheesy plot device. If you're
interested, go read it at
http://www.baen.com/library/0671319728/0671319728.htm
There's several sequels written by Flint and Fans too...