A rain gauge is a meteorological instrument to measure the precipitating rain in a given amount of time per unit area.
The instrument consists of a collection container which is placed in an open area.
The precipitation is measured in terms of the height of the precipitated water accumulated in the container per given time and is expressed in millimetres. Since the same amount of rain precipitation is assumed to be occurring around the container,
the area of collection is not a factor.
However, it should not be too small, neither should it be too large. Due to spatial uniformity of rainfall, 1 mm of measured precipitation is the equivalent of 1 L of precipitated rain water volume per metre squared.
A tipping bucket rain gauge consists of a pair of rainwater collecting buckets. It is covered by a funnel, with an open collector area at the top where A is the area of collection. The buckets are so placed on a pivot that only one bucket remains under the funnel at a time. During rain, rain water is collected in the collecting bucket, through the funnel. When the water fills up to a known point of the bucket, say having a volume v, the bucket tips, emptying the water. When one bucket tips, the other bucket quickly moves into place to collect rainwater.
Each time a bucket tips, an electronic signal is sent to a recorder which is registered by the instrument with time stamp.
A rain gauge (also known as udometer, pluviometer, ombrometer, and hyetometer) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a predefined area, over a period of time.
It is used to determine the depth of precipitation (usually in mm) that occurs over a unit area and measure rainfall amount.
The precipitation is measured in terms of the height of the precipitated water accumulated in the container per given time and is expressed in millimetres. Since the same amount of rain precipitation is assumed to be occurring around the container,
the area of collection is not a factor.