(g) Meteorological Instruments and their uses -
Six's maximum and minimum thermometer,
mercury barometer, aneroid barometer,
wind vane, anemometer, rain gauge and
hygrometer.
Answers
Answer:
This article throws light upon the eight main types of weather instruments. The types are: 1. Barometer 2. Fortin’s Barometer 3. Aneroid Barometer 4. Thermometer 5. Wet and Dry Bulb Thermometer 6. Wind Vane 7. Anemometer 8. Rain-Gauge.
1. Barometer:
The atmospheric pressure is measured with the help of a barometer. There are two types of barometer—Mercurial and Aneroid.
The mercurial barometer—Fortin’s type holds a column of mercury which balances weight of the air. The aneroid type is a vacuum box which measures the atmospheric pressure.
2. Fortin’s Barometer:
The Fortin’s Barometer is made of a glass tube nearly one metre long and open at one end. The glass tube is covered by a metal jacket to give protection. The tube is filled with mercury and held inverted on a mercury container.
The lower part of the container is made of leather which can be raised up or down with the help of a screw. An ivory pointer is attached at the lower part of the metal jacket in such a way that it touches the upper surface of the mercury. A vernier scale is attached to the metal jacket.
3. Aneroid Barometer:
This is another specialised type of Barometer. It is made of elastic metal box and the inside is made airless. It does not contain any mercury or any other liquid. The metal box contains a spring which presses the lid outwards against air pressure. When the pressure outside increases, the lid moves inwards and vice-versa. The movement of the lid makes a needle to rotate over a graduated dial from which reading can be taken.
4. Thermometer:
Six’s Maximum and Minimum Thermometer:
This Thermometer records both minimum and maximum temperature at a time. The mean temperature for a day is calculated by taking average.The Thermometer has two arms and it looks like U. One of the arms is fitted with a scale to record maximum and the other arm has a scale to record minimum temperature. The lower portions of the arms are filled with mercury and the upper portions with alcohol.
5. Wet and Dry Bulb Thermometer:
The atmospheric humidity is measured with the help of Wet and Dry Bulb Thermometer. It is also called as Manson’s Hygrometer. In this instrument, two thermometers are fixed on a wooden plank side by side. The bulb of one of the thermometers is rapped with a muslin and is kept wet by dipping one end to the container of a pure water.
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