In article , Niels Vestergaard Jensen writes:
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).


First of all. Such an event would not scramble the global weather,
it would hardly perturb it at all, although you can always
point to the butterfly effect and develop a couple of storms.

An example: Detonations of atomic bombs in the atmosphere certainly
scrambled the temperature, density and humidity in a more than 10 km
wide sphere, yet there are no indications that it affected
the global weather very much.


Timescales:
Within the local area a few hundred km: A few hours
Europe: A couple of days.
Northern or Southern temperate regions: A week
Tropic areas: A month.
The hemisphe 2-3 months
Globe: 1-2 years.

Øyvind Seland