Chaos

 

Have you ever wondered what it would be like if there was a "second you" in a parallel universe that perhaps decided to step out the door second later than you?  Maybe there was a minor distraction.  How would the life of parallel you change?  Maybe the parallel you would be held up at a red light, and slowly the difference in the day's progression increases. 

 

Weather is just like that.  To predict weather, complex computer models exist that calculate the weather of the future.  In a sense, the development depicted by a model is like a parallel universe that starts out with small differences from the real weather.  One reason for this difference is that we don't know precisely the temperature or wind at every location in the atmosphere (e.g., over oceans).  The result is that these small errors slowly lead to differences in the development of the modeled weather from the real weather.  Theoretically, this difference could be as small as the tiny wind gust produced by a butterfly flapping its wings.  This error growth of computer model simulations is thus sometimes called the butterfly effect, or in scientific terms, chaos.  Chaos means, that tiny differences at the beginning of two otherwise identical scenarios will grow after some time passes.

 

Unfortunately, there is no way of escaping chaos, so computer models will always be wrong after some time.  However, by running many simulations of the future weather, each one with slightly different values at the beginning, weather forecasters can estimate how strong the effect of chaos is for a given forecast: For example, if all simulations spread apart rapidly, the butterfly effect is strong and the forecast is uncertain.  This approach is called "ensemble forecast technique."

 

Scientists at Texas Tech and elsewhere are developing methods to reduce the effect of chaos in weather forecasts and thus help predict when the weather over West Texas turns wild.