If you want to measure the amount of rainwater falling on your land, you can buy a rain gauge or build one yourself. To do this, you just need a few simple materials and a little time available. Use the tool to compare falling water from day to day, week to week, or even monthly.
Method 1 of 2: Create a Rain Gauge with Measurement Scale
Step 1. Cut the top of a bottle
Use scissors carefully to remove the top of a plastic bottle. Practice the cut just below the part where the bottle begins to tighten. Make sure you remove the label completely.
Young children should only cut the bottle under parental supervision
Step 2. Place pebbles in the bottom of the bottle
Plastic bottles are never flat. Pour a few pebbles inside, in order to equalize the bottom and prevent the instrument from overturning due to wind or very strong precipitation.
Step 3. Turn the top of the bottle to create a funnel
Remove the cap and turn the top of the bottle upside down. Place it on the other side of the bottle, with the narrow side facing down. Secure the funnel with masking tape, aligning the edges you cut earlier.
Make sure the top half is securely fastened and that there are no gaps between the two parts of the rain gauge
Step 4. Create the measurement line
Take a long piece of masking tape and attach it to one side of the rain gauge to create a straight vertical line from the bottom of the bottle to the top. Take a marker and, with the help of a ruler, draw a horizontal line just above the pebbles. This is the bottom of the rain gauge.
Use a tape with strong adhesive properties. Other types of tapes may come off due to water
Step 5. Mark half-centimeter intervals
Place a ruler against the tape and align the 0 with the horizontal line you drew earlier. Use a marker to mark half-centimeter intervals along the tape, all the way to the top of the bottle. Write the measurement of each mark, from top to bottom. Make sure the numbers are easy to read throughout the experiment.
- There is no need to mark all the intervals. Just start from the second and write 1 cm. Make sure to wait for the marker to dry before putting the tool in the rain. Avoid using washable markers and making the measurement scale in the rain. If you were forced to re-apply the tape or practice the marks again during the experiment, the results could be considered inaccurate.
- You can choose the unit of measurement you prefer, based on the specifics of the experiment. You can mark centimeters only or you can add quarter centimeters or millimeters as well.
Step 6. Put the tool in the best place
Place it on a flat surface. Make sure it is not blocked by branches and that it is not in the way of people. Pour some water on the bottom, until you reach the 0 mark, so you are ready to use it.
- You can also use colored gelatin instead of water, so that you have a reference point from which to start the measurement. Use gelatin or oil instead of another liquid, which could dissolve and mix with water, invalidating the measurement. Plastic bottles don't have a flat bottom, so you'll need to consider this when deciding where to start.
- Make sure the tool is in a protected area. You need to check that it is not disturbed by wind, debris and anything else that can block the rain or prevent it from entering the bottle, such as branches or power lines.
Step 7. Pay attention to the weather
Check the weather forecast. Inspect the instrument after exactly 24 hours to check the water level. Now you know how much water fell from the sky.
Check how close the measure of the rain you have detected is to the official ones, by reading the news in the newspaper or on the internet
Step 8. Repeat the measurement
You can continue measuring rain for 7-14 days or until you have satisfied your curiosity. If you have been assigned this experiment by a teacher, be sure to follow all their directions and continue recording your measurements until the experiment is finished.
Try to always record the measurements at the same time, in order to have references for 24 hours. Remember to throw out the water after each measurement so that you can start over from scratch the next day
Method 2 of 2: Use a Graduated Cylinder
Step 1. Get a plastic bottle
Find an empty 2-liter plastic bottle that you would have thrown away. You can also buy one at the supermarket and empty it. Make sure it is completely empty and dry before using it.
Step 2. Cut the top
Attach duct tape 3/4 of the way up the bottle to create a horizontal line. Use sharp scissors to cut the bottle at the ribbon. The diameter of the hole must be precise.
Step 3. Turn the top of the bottle over
Once you've cut that part, turn it over and place it over the bottom, creating a funnel. Secure the two parts firmly with staples. You have to make sure that the rain gauge does not break, even in heavy rain.
Step 4. Place the rain gauge
Find the best spot to collect the rain. You have to avoid putting it in a very busy area, where it could be upside down. At the same time, don't place it near buildings or trees, where a change in wind direction can prevent water from entering.
Hold the tool upright by placing it in a bucket or container. You can also dig a hole in which to bury it halfway
Step 5. Check the measurement
Take the rain gauge from its location at the designated time every day to check the amount of water it has collected. Pour the rain into a graduated cylinder. Be careful not to spill the water.
- For example, the cylinder could be graduated in cm, so if you have collected rain for a week and the water you poured into the cylinder reaches the 10 cm mark, you can calculate that 10 cm of water has fallen during the week.
- Compare daily measurements. With pen and paper, record the measurement at the same time every day for an accurate comparison.
Step 6. Consider the drop in the bottle
Most plastic bottles don't have a flat bottom. Before measuring the rain, measure the height of the liquid filling the uneven bottom with a ruler. Subtract this small amount from your final measurement.
Step 7. Analyze the results
Compare the amount of rain you collected with the duration of the measurement. For example, after how many days does the rain reach 15 cm? You can also compare rainfall from month to month, week to week, or day after day. You can also create a chart based on this data, so you can see the changes between seasons.
You can also compare your measurements with wind speed, wind direction or air pressure. Make sure you always place the rain gauge in the same spot
- You can also pour a small amount of cooking oil, baby oil, or any other type of oil inside the container before putting it in the rain. The oil prevents water from evaporating, making the measurement more accurate.
- Remember: if you put a millimeter of oil in the container, you will have to subtract one millimeter from the final measurement.
- If you use a taller, narrower container for your measurements, you can calibrate it to read the measurement directly, without having to do any calculations.
- You should bury the rain gauge lightly so that it remains stationary.