Seasonal storms help clean up stagnant air
When people think of bad weather, they are usually thinking of some type of storm.
During the warm season, it might be thunderstorms with dry lightning or even tornadoes. During the cold season, we worry about snow storms and ice storms.
But it is possible to have a bad kind of weather event that doesn’t involve strong winds or even any type of precipitation. It can occur both during the depths of winter or the heat of the summer. This type of bad weather occurs when high pressure sits over the area for an extended period of time. During the summer, the result is a string of hot and dry days, and during the winter, we either get an enjoyable period of sunshine or are stuck in days of fog.
With either case, however, what can put these situations in the bad weather category, is that the air gets stagnant. Other than the fact that stagnant air doesn’t sound too pleasing, what exactly would make this a bad weather situation? Namely pollution.
Each day, many different types of pollutants are deposited in the air, whether it’s smoke from wildfires or field burning, exhaust from automobiles or snow blowers, or the byproducts of industrial processes. One of the ways that the area keeps from getting bogged down with such pollutants, is that the air is usually in a state of motion, dispersing pollutants and carrying them away.
The air moves, because of the difference in pressure from one location to the next. When a cold front moves through, we usually get strong southwesterly winds behind it, as the air moves toward the departing lower pressure to the east, and away from entering higher pressure from the west.
What happens when a large area of high pressure settles in over the area is that the air pressure differences (called the pressure gradient) become weak, resulting in little air movement.
As pollutants are deposited in the air, they remain and build in concentration, causing our air quality to deteriorate. This is not good for anyone, but can be especially dangerous to people with respiratory illnesses.
When long periods of high pressure and resulting stagnant air are expected, the National Weather Service will issue an Air Stagnation Advisory. You can check on the specific rating of the air quality in your area by visiting www.airnow.gov. This Web site not only gives the air quality rating, but details the problem pollutants. When it comes to stagnant air, all you can do is wait for Mother Nature to bring in a storm to clean things up!