Rain Fall Data Collection - Tipping Bucket Rain GaugeTipping Bucket Rain Gauge Basics

A basic parameter to be collected for most weather / meteorological site studies is rainfall data. A simple low-cost rain fall measuring device that can be used in many applications and locations is a tipping bucket rain gauge. Many variations of tipping bucket rain gauges exist from different manufacturers however most operate on a simple principle.

At the top of the gauge is a funnel of standard diameter that collects rainfall over a known area. The funnel is typically covered with a screen to prevent leaves and other debris from clogging the opening at the bottom of the funnel. The funnel feeds the collected rain into a rocking pair of small buckets... precisely balanced on a center fulcrum... much like a child's "teeter-totter". As the rain fills one bucket, it's weight causes it to rock downward and lift the opposing empty bucket. The rain then spills out of the bucket and the cycle starts again.

Each time the buckets tip, they cause a switch of some type (typically a reed switch) to close momentarily. This contact closure can then be counted by an attached data logger. Rain gauges are manufactured so that each tip (switch closure) corresponds to a particular amount of rainfall... eg 0.01".

Data Logger Interface

Interface to a tipping bucket rain gauge is simply done with the Logic Beach data logging instruments. The switch contacts are directly wired to an Counter type input channel (which already has an internal power supply for powering the rain-gauge switch. The logger can then be configured through the HyperWare software to sample periodically read the Counter channel's value, process it and eventually store it to logger memory.


Rain Fall Totalizing Program Net

Data Logger Program Example

To program the data logger to sample and process the rain-gauge input, the above Program Net can be used. The program is developed graphically in HyperWare (running on a PC) then downloaded into the data logger's memory where it executes. The program functions as follows...

Every minute, the Counter icon (which represents the hardware input channel connected to the tipping bucket rain-gauge) is sampled. This count is fed to a Math icon where the counts are converted algebraically to inches, then passed along to an hourly total Summation icon. The hourly rainfall total is then passed to a daily (24 Hr total) Summation function and every day the 24 hour total is stored to memory. Additionally, the hourly total is also fed to a non-clearing Summation icon that keeps an accumulating year to date rainfall total, which also is stored to logger memory every day.

 

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