Barometers – devices used to measure air pressure that have been around since the 17th century – are very reliable for predicting weather despite the fact that their design hasn’t changed in nearly 400 years.Needless to say, these are very good doodads to have around, especially during the summer months when grilling and chilling outdoors becomes a high priority.Sure, your smartphone is going to tell you the weather, but how often is it right? Do you ever get notifications for rain on sunny days, or vice versa?How Barometers Work
To say barometers work by measuring air pressure
is hardly that helpful, but if you think of air as moving up or down it makes it easier to understand. When air is moving down it creates high pressure, and when it moves up the pressure lightens.Another way is to think of air as being light or heavy. "Heavy" air is air that is moving down and creating more pressure; "lighter" air is moving up and lessening pressure.Old-school barometers measure this pressure in clever devices that rely on liquid movement, while newer (as in 19th century new) aneroid models use a metal cell that is susceptible to very slight changes in pressure.In both designs, air pressure causes an object to move (water, mercury, a spring, etc.) in an observable way.Barometer Reliability
Barometers are very reliable when it comes to short-term weather predictions. High pressure typically indicates good weather, while low pressure means a storm is brewing.To better illustrate barometrically, air rises quickly prior to a storm as it condenses into clouds and rain, creating low pressure at ground level. Conversely, high pressure occurs when air sinks and the moisture in it evaporates.Barometers measure this movement quite easily, which makes them very reliable when predicting the day’s weather.Barometer Readability
Barometers are easy to read – if you know the trick. And, there are different tricks for different barometers.With mercury barometers, for example, a higher mercury level indicates higher pressure and better weather. For barometers with numerical dials, a lower number (always to the left) means stormy weather, and higher numbers mean clear skies.Meteorologists will tell you that real accuracy comes from reading barometer trends over time, and your elevation also plays a role, but it’s still fair to say that barometers are reliable for short-term weather predictions.