Rain Gauges; How to read specifications
Rain gauges are meteorological scientific instruments designed for measuring rainfall. These devices can function as either standalone units or as integral components in multi-sensor weather stations. Comparing different types of rain gauges, you will soon discover a diverse range of mechanisms for measuring rainfall, which means products have specifications and benefits that can vary significantly from one another.
Take our word for it; finding the best rain gauge to suit your needs can be tough! To make your task of wading through the specifications of rain gauges a little easier, Instrument Choice scientists have compiled some key terms and definitions.
Here are the key terms:
1. Rain Gauge
A gain gauge is a device used to collect and measure the amount of liquid precipitation that has fallen in a particular area.
2. Self Emptying Rain Gauge
These are rain gauges that collect, measure then dump the measured rainfall. Most digital rain gauges are self-emptying.
3. Tipping Bucket Rain Gauge
'Tipping Bucket' is a reference to the system employed by this category of rain gauge to collect and measure rain. They are the most common type of rain gauge available, and the mechanism is in a range of stations from the budget-friendly, right up to professional models. Tipping bucket rain gauges consist of a funnel to direct rain, one or two buckets (sometimes called spoons) on a pivot, a reed switch/sensor, and drainage holes. They work as follows:
- The funnel on the top of the rain gauge directs water into the bucket or spoon.
- Once the bucket fills to the pre-calibrated level, it will tip. For single bucket systems, they will tilt and return to the top to start rain collection again. If it is a two bucket system as one bucket falls, the other will rise and start collecting rain.
- Each time the bucket tips, it will trigger the reed switch/sensor, which in turn sends a message to the indoor console that the calibrated amount of precipitation has occurred
4. Weighing Rain Gauge
Weighing rain gauges use a weight sensing mechanism, which is usually mechanical, to measure rainfall.The weight of water collected is measured as a function of time and converted to rainfall depth. Weighing rain gauges are typically more accurate and quantify all forms of precipitation, including hail and snow.
5. Radar Rain Gauge
Radar stands for Radio Detecting and Ranging. The technology uses radio waves to transmit a short pulse that returns to a base unit for measurement whenever the pulse wave bounces off an object in its path. Radar rain gauges use this principle to detect and measure precipitation.
Radar rain gauges are typically less accurate than both tipping bucket and weighing rain gauges. However, radar rain gauges have their niche as, unlike weighing and tipping bucket systems, it is possible to install these on moving objects such as ships.
6. Rainfall
The amount of rain falling within a given area in a given time.
7. Rainfall Records and Rainfall Pattern – histogram graph, etc
On a rain gauge specification, this is an indication of how the rainfall results/patterns present on your console. For example, daily or weekly records may be on a graph, histogram, etc.
8. Range
The range is the scope of the values the device can measure, given as a minimum and maximum possible value.
9. Accuracy
Accuracy is the closeness of a measurement to a specific value. Specifications will express the accuracy of a device as a range, i.e., plus or minus a set amount.
10. Transmission Range
On wireless rain gauge specifications, this signifies the maximum allowable distance between a transmitter and receiver during regular operation.
11. Data Logging
Some types of rain Gauges have data logging capabilities. The instrument either has a built-in sensor for logging or can relay information to an external sensor to store data over an extended period.
12. Alarms
Some rain gauges have preset or user selectable alarms. Alarms can be visual or audible notifications and can notify that a rain event is occurring or exceedance of a maximum value.
Conclusion
Understanding the fundamental terms and definitions of rain gauges will help you confidently decide which rain gauge best suits your needs.
Should you need a bit of help finding the best rain gauge, not to worry, contact on of the Instrument Choice Scientists, we're here to help! Call 1300 737 871 or email [email protected].
Also interesting
Rain Gauges are weather measuring devices that are popular with homeowners and essential instruments for many businesses and professionals. There are several styles of rain gauges that use different mechanisms to obtain precipitation measurements. There are unique benefits associated with each, depending on your application.
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