Dear Lauren: Barometric pressure indicates high pressure systems, which generally have good weather, and low pressure systems, which are generally stormy. If you look at a weather map that shows lines of barometric pressure, sometimes they will be close together, sometimes farther apart. They are like the lines on a topographic map of land. Where the lines are close together, there is a steep gradient, and more wind, where they are farther apart, less gradient, and less wind. The high pressure wants to blow into the low pressure, just as on the topographic map, you would go down hill.

Question submitted by Lauren, Rockland ME, USA