Can you explain to me what atmospheric chaos and the butterfly affect are? & how they affect forecating? thnx!

There are trillions of molecules of gas (oxygen, nitrogen, water vapor, etc.) and trillions of bits of dust and particulates in the atmosphere. If we had enough supercomputing power to completely model the atmosphere, each individual molecule could be modeled and the immediate surrounding area (cubic femtometers) as to temperature, pressure, velocity of the molecule, etc. etc.

The trouble is -- there isn't enough supercomputing power to do this to obtain a super-accurate model, so what they do is take chunks of the atmosphere, say 1 cubic mile chunks and model them, keeping track of temperature, pressure, amount of sunlight passing through, water vapor, all kinds of variables.

One may write some very complex differential equations to model what happens inside each of these chunks to predict heating, cooling, clouds, rain, etc. etc. The problem with differential equations is you need very accurate starting conditions before you 'run' the equations to predict the future. You need initial conditions so accurate that even 64 decimal place accuracy isn't enough.

The butterfly effect is called that, because a butterfly flapping its wings in chunk #10445683 will affect the weather in chunk #99340076 that is 1000 miles away. It is the equivalent of an initial condition to the equation that is in the 70th decimal place (of say, wind velocity in chunk #10445683) and it will affect the results of the equation in the other chunk several months later. One of the problems is, the computer only calculates numbers to the 65th decimal place, so you can't see the butterfly flapping its wings.

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The idea was that the weather that's occuring in one spot on the Earth has influence on weather that will occur at some distant spot sometime in the future.

The "Butterfly Effect", was more of a parable, or a "thought experiment" that was intended to carry the idea to the extreme. Thus far, most scientists believe that the weather system is far too noisy and that in a practical sense, a single butterfly wing flap would be unlikely to make a significant difference in the weather halfway around the planet, a hundred years from now.

Now, if that butterfly somehow caused an airliner to crash into a fuel dump, and the resultant fire or explosion pumped millions of pounds of smoke and CO2 into the atmosphere (referred to as "amplification" in the study of chaos), then I maintain that there WOULD be some effect on the weather in the future. But even then, it's still in the realm of a Thought Experiment.

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