What is the structure and the principle on which a rain gauge works?
A rain guage is an instrument used by meteorologists, scientists, and people in general to measure the amount of precipitation that falls as a result of inclement weather patterns. Most rain guages collect the precipitation, usually rain, and measure it against some type of scale, metric for most of the world, English for the United States. I have a rain guage mounted on a utility pole outside my school. It consists of a large exterior tube, a smaller interior tube with graduated markings, and a funnel that captures the rain and conducts it into the interior tube. The graduated markings are in tenths of an inch; when the interior tube is completely full, it represents one inch of rainfall. The exterior tube serves as an overflow catch in the event of multiple inches of rainfall. To measure the excessive rainfall, simply disassemble the interior tube and funnel, pour out the first inch of rainwater, then measure the oveflow in the exterior tube by pouring it into the interior tube. The largest amount I have ever measured was 5.54 inches of rainfall over a weekend.