Have you ever wondered how scientists measure the amount of rain that falls during a storm? Meteorologists use special tools called rain gauges to gather weather data. You do not need expensive laboratory equipment to track the weather, though! With a few simple household materials, you can craft your own working rain gauge out of a recycled plastic bottle.
To build your rain gauge, gather a clear two-liter plastic bottle, a pair of scissors, a ruler, a permanent marker, some small rocks or pebbles, and some tape. First, ask an adult to help you cut the top section of the bottle off, right where the straight sides begin to curve toward the cap. Set the top piece aside for a moment.
Next, place a layer of small rocks or pebbles into the bottom of the bottle. Because plastic bottles are lightweight, the rocks provide weight so the wind does not blow your gauge over. Pour just enough water into the bottle to cover the rocks completely. This water line will be your starting point, or baseline, for measuring.
Now, place a ruler against the side of the bottle, aligning the zero mark with the baseline water level. Use your permanent marker to draw line marks every quarter-inch or half-centimeter up the side of the bottle. After marking your scale, turn the top cut-off piece upside down and insert it into the bottle opening like a funnel. This funnel shape helps direct falling raindrops straight into the container while preventing water from evaporating quickly. Tape the edges to hold it securely.
Finally, place your finished rain gauge outside in an open area away from tall trees or building overhangs that might block the rain. Check your gauge at the same time each day to record how much rain collected above your baseline. Once you record the measurement, empty the extra water down to the baseline mark so your gauge is ready for the next downpour!
