Weather Instruments

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  • Topic: Rain, Water, Rain gauge
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  • Published : February 24, 2013
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Chapter 6 Measurement of Precipitation
CONTENTS
6.1 Definitions and Units ............................................................................................................ 1 6.2 Observation Instruments ..................................................................................................... 1 6.2.1 Cylindrical Rain Gauges and Ordinary Rain Gauges ................................................ 1 6.2.2 Siphon Rain Gauges ...................................................................................................... 3 6.2.3 Tipping Bucket Rain Gauges ........................................................................................ 4 6.2.4 Tipping Bucket Rain Gauge Recorder ......................................................................... 6 6.2.5 Exposure ......................................................................................................................... 7 6.2.6 Windshields .................................................................................................................... 7 6.3 Maintenance .......................................................................................................................... 9 6.3.1 Sources of Errors ........................................................................................................... 9 6.3.2 Maintenance ................................................................................................................. 10 6.4 Calibration ........................................................................................................................... 12 6.4.1 Instruments Required for Calibration ........................................................................ 12 6.4.2 Methods of Calibration ................................................................................................ 13 6.5 Inspection and Repair (Adjustment) ................................................................................ 14 6.5.1 Inspection in Response to Problems ........................................................................ 16 6.6 Miscellaneous ..................................................................................................................... 19 6.6.1 Installation Environment and Procedures for Exposure ......................................... 19 6.6.1.1 Cylindrical Rain Gauges ....................................................................................... 19 6.6.2 Transportation .............................................................................................................. 20 6.7 Practical Training ................................................................................................................ 22 6.7.1 Tipping Bucket Rain Gauges ...................................................................................... 22 6.7.2 Tipping Bucket Rain Gauge Recorders ..................................................................... 25 Note: Magnification Adjustment for Tipping Bucket Rain Gauge Recorders ........................ 27 1

Chapter 6 Measurement of Precipitation
6.1 Definitions and Units
Precipitation is defined as liquid or solid condensation of water vapor falling from clouds or deposited from air onto the ground. Precipitation in the form of ice flakes, such as snow, is called solid precipitation, and that in the form of water drops is sometimes called liquid precipitation for distinction. Precipitation is measured as the amount of water that reaches horizontal ground or the horizontal ground projection plane of the earth’s surface, and is expressed as a vertical depth of water or the water equivalent of solid precipitation. The unit of precipitation in Japan is the millimeter. 6.2 Observation Instruments

Instruments for measuring precipitation include rain gauges and snow gauges, and various types are manufactured according to the purpose at hand. Rain gauges are discussed in this chapter. Rain gauges...
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