Locating a Rain Gauge
The rain gauge is a tool designed to measure precipitation at a particular location for a given amount of time. It is imperative that they be placed in an appropriate place away from any possible obstructions so that they may produce the most accurate data possible. Things like trees and buildings can get in the way and affect the amount of rain reaching the gauge. Wind is another factor that can have an impact on the accuracy of a rain gauge’s measurements as it can cause splash out.
Finding a proper place for a rain gauge can sometimes prove to be a little difficult. Ideally, they should be installed in an open area, but this should also be a place that is protected from wind coming from any possible direction. A general rule is that a gauge should be placed away from any obstruction, at least twice the height of whatever that object might be. The average user of a home weather station would probably find this rule hard to follow to the letter, so they should just try to keep the rain gauge as far away from any confounding factors as possible and no closer than half the height of the object. If the desired location is particularly far or otherwise difficult, a wireless rain gauge would probably be better than one that has to be connected by cable to the indoor console of the weather station.
It is also important that a rain gauge be placed at a low altitude where it can catch as much rain as reasonably possible. Proven in 1769, rain gauges placed 10 meters above the ground only receive about 80% of the precipitation that those at ground level in the same location do, and gauges placed 50 meters above the ground receive only 50%. Wind is the reason why the measurements were so different and why a rain gauge ideally should be sited no more than two meters from the ground to ensure that the data collected is accurate. A gauge being too low can negatively affect the data, too, as rain can splash into the sensor. The guideline is that they be placed between 0.7 to 2 meters high. However many home users site their sensors on their roofs as this is the only place to avoid rain obstruction which is often the best compromise possible that also allows good air flow to the wind sensors. This typically doesn’t impact rain accuracy too badly.