How to Make Your Own Rain Gauge
A rain gauge is a weather instrument used for measuring the amount of rainfall. There are many types of rain gauges, but the basic device that was invented 100 years ago is still in use today. It consists of a simple cylindrical collection tube with graduated markings.
The markings are calibrated to measure collected rain on a flat area of one square inch of soil. The scale represents water volume in cubic inches. However, since the typical rain gauge is cylindrical showing a column of water, a person may mistakenly think that the device is measuring water depth when it is actually calibrated to reflect cubic inches of water.
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Things You'll Need
- Funnel
- Olive jar
- Ruler with a millimeter scale
- Container with a milliliter (ml) scale
- Pencil and paper or a calculator
Instructions
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1
Remove the lid of an empty olive jar.
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2
Place a funnel in the top of the jar.
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3
Measure the inside diameter of the funnel in millimeters, and divide that number by two (to find the radius).
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4
Square that number and multiply the result by 3.14 to find the open area of the funnel top (the formula for finding the area of a circle is pi times the radius squared).
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5
Place the rain gauge in an open area to collect rainwater. After a rain, pour the water into a container that is calibrated in milliliters.
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6
Divide the amount of rainwater in milliliters by the area (which was calculated above). This is the amount of rain in milliliters.
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TV and radio meteorologists often report rainfall in "inches" rather than "milliliters." To convert milliliters to inches, simply multiply the number of millimeters by 0.039 inches.
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Once you have some measured quantities of water, you can tape a piece of paper on the side of the olive jar and make markings to create a scale. Place a piece of clear adhesive tape over the paper so it will not get wet when the device is placed in the rain.
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