How to read a barometer

The most important instrument used for weather forecasting is the barometer, but surprisingly only a handful of people know exactly how to read a barometer and interpret its measurements. A barometer does not only  indicate present weather conditions but forecasts probable weather conditions 12 to 24 hours in advance.However it's not that simple to read a barometer, taking into consideration the fact that the wind changes its direction constantly. A "rise" in barometric pressure must be considered in relation to the former reading and the same principle applies to a "fall". In fact, a barometer is most useful if it is read only once a day, preferably at the same time of the day - 7-8am or 8-9pm are good times to do barometer readings - for reasons which we'll get to later. Twice a day is also fine, but it's really the 24 hour changes which are most significant for weather forecasters, so learning how to read a barometer is of great importance at this point. Sometimes the readings of the barometer can appear inaccurate saying that there is going to be rainy but in fact it's going to be sunny. That happens because the weather we experience is caused by the interaction of air masses and pressure cells, which move fairly slow over the earth's surface. Considering only air pressure varies, the extremes are high pressure cells and low pressure areas are the fronts, these two being the boundaries between different air masses. Between these extremes air ...
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The Classic Pocket Barometer

Pocket barometers are just an alternative to the standard mercury barometers being smaller and lighter. A pocket barometer is similar to the mercury barometer and has all of the same functions as a regular mercury barometer. A good thing about the pocket barometer is that it and can be easily transported wherever needed. On the other hand, the disadvantage of a mercury barometer is that it's bulky and fragile and makes transportation hard. There are several things that could go wrong with a mercury barometer, things such as the glass tube could easily brake or the mercury might become difficult to read under unsteady conditions such as in a car on the road. Pocket barometers are based on different principles than the mercury barometers and they're also known as aneroid barometers because they function without any type of liquid. The aneroid barometers were invented by the French physicist Lucien Vidie in 1843 and are a newer type of barometers. An aneroid barometer is a container that holds a sealed chamber from which some air has been removed, creating a partial vacuum. An elastic disk covering the chamber is connected to a needle or pointer on the surface of the container by a chain, lever, and springs. As atmospheric pressure increases or decreases, the elastic disk contracts or expands, causing the pointer to move accordingly. Aneroid barometers are even more popular than mercury barometers since they're based on a newer and safer technology that doesn't imply mercury which can be if not handled ...
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