"Martin Sykes" wrote in message
...


http://www.users.globalnet.co.uk/~sykesm
"J C-W" wrote in message
news
big snip
this thread tells us is that for all the technology and super computer
models being used, the predictions are fundamentally flawed because they
rely on basic physical principles and ignore chaos theory, quantum
mechanics

As I understand modern weather prediction, they acknowledge the existence
of
chaos. Chaos does not violate the laws of physics but simply acknowledges
that even simple laws can give rise to complex behaviour which can be
massively influenced by minute variations in the initial state.

To get over this they run millions of simulations with small variations in
the input state. For some states, all simulations run very closely but for
others they diverge quickly. They then use all the simulations to give
statistics like '70% probability of rain' which really means that in 70%
of
the simulations it rained and in the other 30% the simulation took a
different course and it remained dry.

I doubt if they run millions of simulations for one situation. If they did,
it might take them a year to produce tomorrow's forecast Two or three
closely similar cases probably would be enough for them to form a judgement
as to whether they are in a chaotic regime or not.

Franz