butterflies over the amazonas jungle

[Ulrich Grepel <uli@intellektik.informatik.th-darmstadt.de>]

hi,

in my latest rambling about astrology I presented an example of butterflies
in the Amazonas jungle causing a hurricane over Florida. Someone (sorry,
don't remember who) was asking for an explanation.

This example shows how relevant every single bit of information about
weather data is when you want to forecast the weather for more than about
two weeks or so. A small and single event very far away can cause very big
events somewhere else, If you want more I can provide you with a mathematical
(admittedly special) example that shows the thing with the need for precision.

The butterfly-example came up when some scientists did some weather simulations
on a computer. Changing the last digit of just one input parameter caused
a totally different weather one or two months later. Like snowstorm<->hundred 
degrees Fahrenheit. That big difference was due to promoting of 'errors' in
the calculations. It's a real wonder how relatively stable our climate is
when you think about these facts.

Bye,

Uli