I'm sure there has to be more to it than they're giving in the article. People use fractal algorithms to generate clouds for displaying in video games.

Maybe they have just found the common scale factors and recursion patterns that happen in the weather, and they figure out the parameters that would normally be random by analyzing the current cloud cover, then let the values vary slightly to figure out what could happen.

The fractal algorithms can be hard to get your head around, but they're easy-ish to implement:

//Pseudo-java
//ARGH Preview shows that formating was lost. Suck.
void fractalGen(Point center, Float width, Color color, Screen screen, Float scale)
{
if( width {
screen . plot(center, color);
}
else
{
//break up the width somehow to cover the area given
Float newWidth = width / scale;
Point[] newCenters = breakUpArea(center, newWidth);
for(Point newCenter : newCenters)
{
Color newColor = fudgeColor(color);
fractalGen(newCenter, newWidth, color, screen, scale);
}
}
}

Basically just decide how you're breaking up the section of the array (screen) you're given, the scaling factor, and how you fudge the value (color) that you're given, then recurse down doing that to each sub-area until you hit your arbitrary stopping point.

You can also implement them bottom up, which tends to perform better and require fewer resources, but is significantly more complicated.

Any time I see complex behavior emerging from simple premises, I think things are on the right track. Doesn't seem to get much simpler than that algorithm. Then again, recursion makes my head hurt, so maybe I missed something.

Except that algorithm goes backwards. starting from the macroscopic level and subdividing into smaller levels. Most observable phenomena start with a seed and grow larger from there.

It could actually be something even greater if it works that way, though. Most of the real advances come from being able to take a desired result and step back through the necessary construction process to make things come out that way. If the system can reliably determine the start values from which weather springs, we may be on our way to taking direct control over the weather.

Which will send the AGWers into apoplectic fits of rage, once we can reverse global warming any time we want. Remember, being an environmentalist isn't about protecting the environment, it's about destroying humanity so we won't affect the environment any more.