Part of the show Forecasting Weather and Climate
Greg in Texas asked:
We're having a nasty dust storm at the moment, which brings me to my question: what causes wind gusts?
Friction basically. We have a theoretical wind speed which we call the geostrophic wind speed and that's just the speed you would have if there's no friction. But when the air that is moving is in contact with the ground, then you get friction. This takes a bit of energy out and makes the bottom of the atmosphere very turbulent. That's where you get the gusts from. It's this turbulence and mixing at the bottom that causes gusts.