Weather Whys; Advection

This is weather wise. When a meteorologist puts together a forecast, he's primarily interested in what sort of air is moving into his region. Wind is simply a current of moving air, and it has certain characteristic properties. But when air moves from one region to another, meteorologists call it advection. It might show itself as warm, moist air moving inland from the Gulf of Mexico, or it might be very cold air like the arctic blasts which the northern and central plains experience during the winter. Warm advection is warm air flooding into a region, and if a meteorologist sees that in the weather picture for tomorrow, he'll likely forecast temperatures which are a little higher than today's. Other properties of the atmosphere can be advected too. For instance, there's a phenomenon called vorticity advection. It sees the amount of rotation in a mass of air, and positive vorticity means there might be a storm brewing.

Negative vorticity generally means fair weather. So if a meteorologist looking at his weather maps sees pva or positive vorticity advection, that means stormy weather could be moving in. He might forecast cloudy sky, or even rain. On the other hand, nva or negative vorticity advection suggests a forecast of clear weather. Moisture advection is important in the formation of the big thunderstorms which rumble across the plains. Winds blowing north from the Gulf of Mexico often bring warmth and moisture with them. In the spring, that often happens ahead of storm systems moving out of the rocky mountains. So when residents of the southern plains notice warm humid air on a spring afternoon, they know the atmospheric process of advection may be setting the stage for another round of severe weather. Otherwise, as a production of KGOU radio and the Center for Analysis and Prediction of Storms at the University of Oklahoma, for weather wise, I'm Chris Barlow.