We're trying to model an atmosphere that has an infinite number of layers from where we live.

To the top of the atmosphere is not 9 12 13 different layers.

It's an infinite number, but you can't put infinity into a computer and expect an answer because it will just hang up and keep running.

The difference between the two models is trying to get a model run that's accurate and timely, timely meaning.

We can have a perfect forecast for a two day snowstorm, but it might take 24 hours worth of running the computer to get there.

So it's a two day forecast that's only good for one day.

Is that worth it?

No.

We try to get it to run in four hours or less.

Now the European model does take longer to run.

There's more data in the European model, and so therefore, it can be slightly more accurate.

But the American model is pretty close.