How is rain gauge used?

Answer 1

Rain gauges are used to measure the quantity of precipitation that will fall into a cylinder. A primitive rain gauge could simply be an empty soup can. The rain falls and you measure the amount of rain with a ruler. Typically the gauges have a funnel into a smaller cylinder and knowing the circumference of the two cylinders an easy to read scale can be put on a measuring stick or on a plastic interior gauge.

If you have a network of gauges in an area, using interpolation across that area, the amount of water in say cubic feet could be calculated to predict runoff into streams. Or in dry conditions the amount of water that could percolate into a particular type of soil.

Another use is tocompare the rain gauge readings with the National Weather Service Doppler RADAR estimates, to calibrate the RADAR estimates for a particular rain event. Snow needs to be melted down after falling a gauge without a funnel, to determine the water equivalent.