Long before now, several scientists wanting to measure rainfall came up with a few designs of rain gauges. The Ancient Greeks and in India were one of the first to create tools to measure rainfall. Then came Korea which first to create a standardized gauge called a Cheugugi.
We have rain gauges which are made up of the following basic components
- The Circular Collector which collects a particular volume of rain and also separates the area of the sample
- The Funnel which channels the amount of rain collecting into the actual measuring device. In some, it is a reservoir to hold the volume until it is measured. A reservoir has a narrow conduit which helps prevent the possible entrance of debris. Debris may clog the model as well as evaporation of the collecting rain, especially during hot weather.
Rain gauges are not used only for rainfall; they also use the measurement of snow and other forms of precipitation. For the later, there needs to be cautious when keeping the rain-gauge especially after a volume of rain has already been collected in the reservoir. Being careful is to prevent the trickling of thawing ice into the reservoir when the device is left especially during a snowy day and when measuring process has not commenced.
How is rainfall measured?
Different countries have different units of measurements. In the United States, measuring is in inches. What does the inch mean? This measurement goes with a time frame usually in hours. The inches in an interval of time tells the depth of water layer resulting after rainfall within a space of time. It gives an idea of how many volumes of water is emptied by the clouds. The volumes will be easy to measure if there are no runoffs, no accumulation in surface waters such as streams, rivers, lakes, seas, and oceans. That is assuming the earth surface to be flat, bare and unmoved.
However, it is almost impossible to give an accurate account of the volume of water after rainfall in an interval of time. The rain gauge placed in a position to collect rainwater directly from the clouds without interruptions will do a good job.
How rain gauges work
Well, the general working principle of rain gauges is simple! For the standard rain gauge, it works by catching drops in a funnel-shaped collector which is attached to the measuring device through a tube. Magnifying ten times the liquid formed from the raindrops caught which enable better precision as it accommodates discrete values as low as a hundredth of an inch. The device is with an outer shell which collects excess water from the funnel and returns it to the mechanism to record. There are other forms of the rain gauge which work with the same principle but have slight variations in set up and method of data delivery as we have in the following:
- The Tipping Bucket rain gauge which has the collecting funnel leading to two other buckets which are smaller in size.
- A weighing rain gauge which has a vacuum that accommodates the effects of the wind among others.
Measuring rainfall is not a job limited to only the meteorologists. With good knowledge of the working principle and how to measure with the instrument, you can readily read the rain amount and not entirely rely on the local channels or websites which provide information for areas miles away from home. Get versatile!
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Here is a video from CoCoRaHS HQ that explains the basics of measuring and reporting rain.