How to use a rain gauge

A rain gauge is also called a rain gauge or a rain gauge. It is an instrument used by meteorologists and hydrologists to measure the amount of precipitation in a certain area over a period of time (measuring snowfall requires the use of a snow gauge). There are two common types: siphon type and tipping bucket type.

1. Structure:

The rain gauge consists of a water container (funnel), a water storage cylinder (outer cylinder), and a water storage bottle, and is equipped with a special measuring cup proportional to its diameter< /p>

2. Classification:

There are many types of rain gauges, the common ones are siphon rain gauge, weighing rain gauge, and tipping bucket rain gauge.

①Siphon rain gauge

The siphon rain gauge can continuously record the amount of liquid precipitation and the number of precipitation hours. The precipitation intensity can also be understood from the precipitation records. The siphon rain gauge consists of a water container, a float chamber, a self-recording clock and a casing.

②Weighing rain gauge

This instrument can continuously record the weight of the precipitation on the rain cup and stored in it. The recording method can use a mechanical clockwork device or a counterweight system to record the weight of all precipitation, and can record snow, hail and mixed rain and snow precipitation.

③Tipping bucket rain gauge

The tipping bucket rain gauge is a remote measurement rain gauge composed of a sensor and a signal recorder. The sensor consists of a water container, an upper tipping bucket, a measuring tipping bucket, It is composed of counting tipping bucket, reed switch, etc.; the recorder is composed of counter, recording pen, self-recording clock, control circuit board, etc.

3. Installation:

Place it on a fixed shelf in the observation site. The mouth of the organ should be kept horizontal, 70 cm above the ground. In areas with deep snow in winter, a backup shelf should be installed nearby that can make the height of the rain gauge mouth from the ground reach 1.0-1.2 meters. When the snow depth exceeds 30 cm, the instrument should be moved to the backup stand for observation. < /p>

4. Observation:

Most rain gauges use millimeters as the unit of measurement, and sometimes the measurement results are also in inches or centimeters. Rain gauge readings can be taken manually or using an automatic weather station (AWS), and the frequency of observations can vary according to the requirements of the collection unit. In most cases the collected rainwater is no longer retained after observation, but a few weather stations retain samples for contamination levels or other testing.

5. Record:

The measurement of rain gauge is limited. There is no point in using a rain gauge when the winds are too strong (tropical storm or hurricane), because while causing damage to the gauge itself, the recorded results will also have excessive errors. In addition, rainwater adhering to the barrel wall or funnel can cause slightly smaller measurements.

Another common problem is that when temperatures are near freezing, rainwater can freeze as it falls on the rain gauge, causing a clogged funnel or other problems. Like other meteorological instruments, rain gauges should be placed in open areas away from buildings and trees to minimize observation errors.