This week, we are going to study the relationship between barometric pressure and wind speed and direction. If you watch the weather forecast during the news, you will usually hear the meteorologist (or weather reporter, as the case may be) state what the air pressure is for the day and in what direction it is changing. As we have seen above, differences in air pressure are what causes air to move from one place to another. If the local air pressure is decreasing, then this means that the area is becoming a lowpressure area, and that wind will start blowing into the region. If the lowest air pressure in the region is at a location, then this is the place where air is ascending, which can result in precipitation as the air going up cools and increases relative humidity to 100%. If the air pressure is increasing, then the reverse of this can happen. If a location is a local high pressure, the result is usually cloudless, sunny days as air is descending from above where it has little moisture.