Saturday 16 May 2015

Weather Instrument pt. 1

A Simple Thermometer

The Simple Thermometer

The Simple thermometer is an instrument used for measuring temperature. Temperature is measured in a scale called Fahrenheit (F) and in Celsius (C). The bulb of the thermometer contains either mercury or alcohol which is easily visible. If the air gets hotter, the mercury or alcohol expands and rises. If the air gets cooler the mercury or alcohol contracts and falls. A reading is then taken.



The Aneroid Barometer
A barometer is a weather instrument used to measure atmospheric pressure. Atmospheric pressure is measured in millibars. There are two main types of barometers. They are the mercury barometer and the aneroid barometer. A mercury barometer has a glass tube. The tube is sealed at one end and filled with mercury. If the atmospheric pressure is high, then the weight of the air will press down the mercury and force it to rise in the tube. The aneroid barometer does not involve liquid, it uses a small, flexible metal box called an aneroid cell, which is made from an alloy of beryllium and copper. Small changes in external air pressure cause the cell to expand or contract.

The Anemometer

An anemometer is an instrument used for measuring wind speed in kilometres per hour. It consists of a set of cups attached to a rotating shaft. As each cup in turn faces the wind it is pushed back, causing the shaft to spin. The shaft is connected to a speedometer which shows the speed of the wind.

To Be Continued...

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