Atmosphere And Weather

How to use a Barometer

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"How to use a Barometer"
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A cow's tail to the west is weather coming at its best;
a cow's tail to the east is weather coming at its least

You really may not be able to accurately forecast the weather by going by such old sayings. A cow's tail has never really been a reliable indicator of weather predictions. However, on the other hand, you certainly cannot afford sophisticated equipment used by the pros such as satellites or Doppler radars. So what to do if you would like to engage in some professional weather prediction? Not all chances are really lost, since you may still be able to to forecast the weather by using a merely inexpensive piece of equipment called a barometer.

Barometers are believed to have been invented by Evangelista Torricelli an Italian physicist and mathematician in 1643. Their main function is to measure atmosphericic pressure. Because high pressure is indicative of fair weather, while low pressure is indicative of storms, barometers work very well for the purpose of predicting weather.

Barometers have shown the capability of providing forecasts 12 to 24 hours in advance. There are different varieties of barometers for sale ranging from plain, simple barometers, ornamental and ultimately, pretty sophisticated ones amounting even to several hundreds of dollars. Of course, you get what you pay for.

The levels of atmospheric pressure can be easily read in a barometer by looking at the dial. The levels are commonly expressed in "inches of mercury", however professional meteorologists like to use "millibars" as a method of expressing atmospeheric pressure. Most barometers will have a second ring on the dial expressing the pressure in millibars.

Upon purchasing your first barometer, just as a clock, you must adjust it accordingly. The best way to accomplish this is to tune on to your local weather channel and check for their local atmospheric pressure reading. In order to work properly, you will have to record this local reading by unloosing a screw that is placed on the back of the barometer and moving the steady hand until it matches the local forecast reading.

In order for a barometer to work effectively, it must be placed in an area with no major temperature changes. Avoid placing it near open windows were drafts are common or in direct sunlight with the sun beating on it at different times of the day. Rather, choose a shady place with a steady temperature where the outside elements will not interfere with its correct functioning.

Now that your barometer has been set you must learn how to interpret its readings. The dial already is equipped with terms such as "rain, dry, wet, etc. however, careful observations of the readings are the most reliable.

An increase of air pressure indicates fair, dry, weather.

A decrease of air pressure indicates approaching storms with rain and winds.

A sudden drop in pressure within a short time may indicate an approaching storm within 5-6 hours.

A slow, large drop in pressure may indicate a long period of poor weather.

A quick rise in pressure when it is low may indicate a short period of fair weather.

A slow , long rise in pressure may indicate a long period of nice upcoming weather.

Look at the readings daily and if interested, you may create a chart where to record the readings on a day by day basis so to have a better grasp of how the weather is affected by atmospheric pressure shifts. While a barometer may be quite helpful in understanding weather, there are also many other factors that must be considered such as wind, elevation and the local weather characteristics of the region.
As seen a barometer is really the closest you can get to predicting the weather as the pros. Find the type that meets your expectations and your budget. Welcome to the wonderful science of metereology!

More about this author: Janet Farricelli CPDT-KA

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