An anemometer is a device that measures wind speed. Invented in 1450 by Italian art architect Leon Battista Alberti, many different kinds of anemometers are still utilised in 2010. Coupled with modern technology, they can be used to tell us certain aspects about oncoming weather patterns.
The most familiar form of the anemometer is the cup anemometer, which was designed in 1846 by Dr. John Thomas Romney Robinson. It uses four cups mounted on horizontal arms, each one attached to a vertical shaft. Wind velocity can be determined by the movement of the cups on the device. Another type of anemometer, the laser Doppler, measures the wind's effect upon a laser, and a sonic anemometer uses sonic waves to do the same thing. Windmill anemometers use a propeller to judge velocity, spinning on a vane in order to face the proper direction.
Wind Speed and Pressure
Different kinds of anemometers may measure wind in slightly different ways, but wind velocity and wind pressure are closely related to each other, so anemometers tend to give information about both. For instance, differences in pressure will cause wind to accelerate from high pressure to low pressure. Dropping pressure and increasing wind speed are usually signs of inclement weather.
Wind Force Scale
There are several different scales that may be used to determine the state of a storm by the ferocity of its wind. The Beaufort wind force scale, for instance, is a 12-point scale that judges wind speed based on sea conditions. It can also be used for land conditions as well. A zero is a calm condition that has negligible wind speed. A 12 on the scale is a hurricane-force condition that has speeds of over 73mph.
The Beaufort scale is a general scale and cannot take every factor into account, so different regions might have their own scales. The Saffir-Simpson Hurricane Scale, for instance, is used in the western hemisphere between the east Pacific and the Atlantic. Tropical depressions and tropical storms are measured for speeds up to 73mph. Above that, hurricanes are based on a one to five scale. Hurricanes categorised as a five have wind speeds above 156mph.
Because the anemometer measures the wind, it cannot offer a full prediction of the weather. There are many other important factors like temperature and humidity. However, coupled with such factors, the anemometer is an important tool that can be used to decipher future weather patterns that are in the process of forming.
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