What is an Analog Barometer?

The "Other" Barometer
In 1643, Italian scientist Evangelista Torricelli invented the first barometer using a 34-foot tube filled with water. He later improved the design by using a 3-foot tube filled with mercury. As atmospheric pressure changed, the force on a small mercury-filled cistern changed, which in turn raised or lowered the mercury inside a glass column.

Enter the Analog Barometer Years later, the analog barometer came into being. A lot shorter than 3-feet, these new barometers were easier to carry. Also, analog barometers have no liquid to loose. In fact, another name for analog barometers is aneroid, meaning "without water". And because aneroid barometers do not use toxic mercury, these models are safer to use.

Inner Barometer Workings
Inside the analog barometer is a metal box called the cell. This cell is a complex mechanism of bellows and springs that expands or contracts with the changing air pressure. Both mercurial and analog barometers display pressure changes under the same principles. Measurement units vary, but are usually in inches or millibars. For an efficient explanation, assume the normal pressure for any area is 27 inches. Here are the possible conditions that the atmosphere might experience:

• Stable reading: If the analog barometer stays at 27 inches, the weather is stable. No immediate changes are likely to happen.
• Pressure rises: If analog barometer readings go above 27 inches, air masses get more stable. Because this mass experiences even less movement, urban areas may experience smog.
• Pressure sinks: Falling analog barometer readings are usually associated with winds and storms. Lower barometers tell a definite change is on the way.

And the Exceptions
Of course, if forecasting weather were that easy, nobody would ever be angry at the weatherman. Accurate analog barometer readings are a great help for meteorologists, but it does take time to learn how all the various atmospheric pressures make weather happen.