Types of Rain gauges.pptx

Study types and specifications of different rain gauges.

1. RAIN GAUGES Presented By Prof. S. R. Satpute

2. Rain gauge A rain gauge is an artifact used in meteorological stations to help measure and collect precipitations that fall in a certain place. Precipitations are all hydrometeor falling to the earth from the atmosphere, including rain, drizzle, hail, snow and sleet, fog etc. There are two types of rain gauges, non- recording type and recording type. 2

3. Non- Recording Type Rain- Gauge: 3 It gives only total rainfall occurred during particular time period. most commonly used type is Symon’s rain-gauge.

4. Symon‘s rain gauge 4 It gives the total rainfall that has occurred at a particular period. It essentially consists of a circular collecting area 127 mm in diameter connected to a funnel. The funnel discharges the rainfall into a receiving vessel. The funnel and the receiving vessel are housed in a metallic container.

5. Recording type Rain gauges 5 These are rain gauges which can give a permanent, automatic rainfall record in the form of a pen mounted on a clock driven chart. From the chart intensity or rate of rainfall in cm per hour or 6 hrs, 12 hrs and total amount of rainfall can be obtained. There are three types of recording rain gauges Weighing bucket type Tipping bucket type Floating or natural syphon type rain gauge

6. Advantages of recording rain gauges 6 Necessity of an attendant does not arise Intensity of rainfall at anytime as well as total rainfall is obtained, Data from in accessible places can be continuously obtained once gauge is established. Human errors are eliminated. Capacity of gauges is large. Time intervals are also recorded.

7. Disadvantages of recording rain gauges 7 High initial investment cost. Recording is not reliable when faults in gauge arise (mechanical or electrical) till faults are corrected.

8. Weighing Bucket Type Rain Gauge 8 It is most common self-recording rain gauge. It consists of a receiver bucket supported by a spring or lever balance or some other weighing mechanism. The movement of bucket due to its increasing weight is transmitted to a pen which traces record or some marking on a clock driven chart. The instrument gives a plot of the accumulated rainfall values against the elapsed time and the curve so formed is called the mass curve .

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10. Tipping Bucket Type Rain Gauge 10 It is a 30cm sized circular rain gauge adopted for use by US weather bureau. It has 30cm diameter sharp edged receiver and at the end of the receiver is provided a funnel. Pair of buckets are pivoted under this funnel in such a manner that when one bucket receives 0.25mm of precipitation it tips discharging its rainfall into the container, bringing the other bucket under the funnel.

11. tipping of bucket completes an electric circuit causing the movement of pen to mark on clock driven receiving drum which carries a recorded sheet. These electric pulses generated are recorded at the control room far away from the rain gauge station. This instrument is further suited for digitalizing the output signal. 11

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13. Floating or Natural Syphon Type Rain Gauge 13 The working of this type of rain gauge is similar to weighing bucket rain gauge. A funnel receives the water which is collected in a rectangular container. A float is provided at the bottom of container, and this float raises as the water level rises in the container. Its movement being recorded by a pen moving on a recording drum actuated by a clock work.

14. When water rises, syphon releases the water outwards through the connecting pipe, thus all water in box is drained out. This rain gauge is adopted as the standard recording rain gauge in India. curve drawn using this data is known as mass curve of rain fall . 14

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