Weather Whys; Thickness

This is weather wise. Much of weather analysis and forecasting depends on the collection of several key readings from locations around the globe. Some of those readings are for temperature, barometric pressure, and the speed and direction of the wind, all taken at several important levels of the atmosphere. But once the readings are taken, there are a variety of ways they can be used to help meteorologists prepare the best possible forecast. When it comes to the barometric pressure, one concern is thickness, which is simply the difference in altitude between the points where two pressure readings are taken. Imagine you're rising through the atmosphere in a hot air balloon and you have a barometer with you. You've noted the pressure at the ground and you want to find out how high you'll have to climb for the pressure to drop by 50%. You might have to go up three miles to find the barometric pressure you're looking for. But depending on the pattern of high and low pressure systems in the atmosphere, the height at which your barometer reads a certain pressure changes every day.

So the distance you'd have to travel to find the lower pressure tomorrow would likely be different than what you found today. That distance is what's called the thickness. Thickness is useful in several ways. For instance, meteorologists often use it to help them properly locate weather fronts. And when a winter storm is forecast to move into a region, thickness is also useful in figuring out which areas will get snow and which will receive only rain. We'd like to know what you think of Weatherwise. Please write us at Weatherwise, KGOU Radio, the University of Oklahoma, Norman, Oklahoma, 73019-0250. For Weatherwise, our writer is Christine Harbour, our editor is Brian Walking, and our executive producer is Karen Hope. Weatherwise is made possible by a grant from the National Science Foundation. For Weatherwise, I'm Drew Barla.