How to Easily Test Your Rain Gauge Calibration

A Rain Gauge measures the daily and hourly rainfall in inches for determining the depth of precipitation over a unit area. In easy words, it measures the rainfall amount for improving weather predictions. A Rain Gauge Calibration test is done to mark the standard scale of reading for more accurate measuring.

This test is a pretty simple one. It can easily be done after cleaning your rain gauge and checking its levels. The easiest and most convenient way to calibrate your rain gauge is by simply measuring the water amount and adjusting the calibration screw. You will be needed to make a few mathematical calculations and handle things properly to get the most accurate results with just a few adjustments. If you feel the testing procedure difficult, then here is the review of the best rain gauge list available on the market.

What you’ll need:

  • Pouring Pitcher measuring about 1 liter
  • Tape measure
  • Calculator
  • Screwdriver
  • Paper and pen

 Step 1: Calculate the Area of the Pitcher

The first step and an important one of these tests are to find out the total area of your Pitcher. This needs to be done to be aware of the total inches of water that will be poured into your gauge. You can easily measure the circumference around your Pitcher, multiplying it by itself and then multiplying by its depth.

A couple of pints are more than enough for this experiment. Mark the distance from the bottom of the Pitcher up to 2 pints. This will help you to know how many inches of water will you be using once you fill it till the marked area, which will pretty much be ½ a liter. Thus, the calculations will give you the number of inches in ½ liter of the liquid in your vessel. That is the total inches and can even be calculated to the 10th place.

Step 2: Pour Water into the Rain Gauge

When you are through with the calculations, you may now add water to your rain gauge. You have to be pretty steady and make sure that every last drop gets in to ensure the most accurate readings. As this step is completed and you have emptied your vessel containing half a liter of water into the gauge, look at the results.

Please read them and compare them with your inches’ calculations. If the amount is under the one you have calculated, you will have to adjust your rain gauge to show the true number. The same goes for when the gauge shows results that are over your previous calculations. You may repeat this process over and over again till you achieve the desired results.

Step 3: Calibrating the Rain Gauge

This is yet another important step that requires a lot of patience. To calibrate your rain gauge, you will need a screwdriver to calibrate the screw of the rain gauge. You may be required to measure the exact amount of water over and over again, ½ liter in this case, as long as you get the calibrations right.

All rain gauges are different, and adjusting them can differ from one device to another due to their design, so remember to be very thorough with your measurements, calculations, and readings. The key is to get a consistent reading every time you repeat the cycle of pouring the ½ liter water into the gauge. As you keep on pouring the watering, you will continue to adjust your rain gauge to make it closer to your true number.

It is important to remember that rain gauges are fragile devices, so you need to be careful while draining the water as not doing so may lead to breakages and malfunctions. The calibration screw should not be turned too far in one direction which the other is in another direction. This may lead to the snapping of the spring that makes the rain gauge operate. Rain gauges must be tested regularly to verify the legibility and accuracy of these devices.

Important Tips

Remember that rain gauges are delicate devices and can be broken easily with a little slip. Be extremely careful while calibrating them and making sure that no child or pet is near your experiment. If you can’t find yourself to match the rain gauges’ exact readings, visit a professional and get it checked for malfunctions. Keep a cleaning schedule for your rain gauge for the best results.

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