Why should I care about the barometric pressure? Just about every TV weather report I’ve ever seen mentions it, along with whether it’s rising or falling, as if this is supposed to be meaningful. Well, not to me it isn’t. What’s the story? Is this just a useless piece of erudition the weather creatures throw in to make their forecasts sound scientific, or am I missing out on something? –Mary M.Q.C., Chicago
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Could be, buttercup–ever try it with raspberry sauce on the beach at midnight? Definitely an experience. But I suppose that’s not what you had in mind. Actually, it’s not true that all TV weather forecasts mention barometric pressure. More often than not, in fact, they skip it, for just the reason you’d expect–most folks have only the vaguest idea what it means. Barometer readings are nonetheless an indispensable part of weather forecasting, because pressure differences are what make the winds blow. More to the point, areas of high and low pressure are the pivots about which regional wind systems rotate.
Many people tend to associate high pressure with fair weather and low pressure with storms. That’s true up to a point, but it’s just as important to know whether the pressure is rising or falling. If the barometer is at 30 inches or more and rising, you can be reasonably sure there are clear skies ahead, whereas if it’s below 30 and falling, you can expect clouds and precipitation. On the other hand, if the barometer is steady, or if it’s low and rising or high and falling, the weather is less predictable.
