The most common rain detector used in electronic weather stations is the "tipping bucket" type of rain sensor. This interesting technology uses two small "buckets" mounted on a fulcrum (balanced like a see-saw). The tiny buckets are manufactured with tight tolerances to ensure that they hold an exact amount of precipitation, typically .01 inch. The tipping bucket assembly is located underneath the rain collector, which funnels the precipitation to the buckets. As rainfall fills the tiny bucket, it becomes overbalanced and tips down, emptying itself as the other bucket pivots into place for the next reading. The action of each tipping event triggers a small switch that activates the electronic circuitry to transmit the count to the indoor console, recording the event as .01 inch of rainfall. On a wireless rain gage, that count is transmitted via a radio signal.
For detailed information about weather station set up, please review that section elsewhere in our education center. Be aware that the accuracy of a tipping bucket rain gauge degrades significantly if it is installed on a non-level plane, so it is critical that it be mounted on a level surface (a bubble level can be used to make sure of it). The surface should also be free of vibration. Follow the manufacturers instructions when installing your tipping bucket rain gauge and be sure to verify that the path for water runoff from the drain screens is unobstructed.
Once the rain detector has been installed, you will need to check to see if the bucket assembly has been secured from movement during shipment. Often manufacturers use some type of fastener (like a cable tie) to hold the assembly steady until it's been installed. If you find that there is a fastener, carefully remove it.
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