A rain gauge is an instrument used to record the amount of rain. You can build a simple rain gauge at home from a plastic bottle and a ruler. The only thing you will have to do next is calibrate the rain gauge to be able to take accurate readings. This can be done by adults, but it's also a great science activity for kids.
Part 1 of 3: Build the instrument
Step 1. Peel the label off a plastic bottle
The most common options are a 16.9 fl oz (500 ml) bottle or a 67.6 fl oz (2 liter) bottle. Whichever you choose, peel off or cut the label off the bottle. This will allow you to clearly see the inside of the bottle, as well as mark the outside.
Step 2. Cut off the top of the bottle
Use scissors or a utility knife to cut the top of the bottle. Cut right where the sides begin to slope inward toward the mouth of the bottle. This will leave the most space in the rain gauge and give you a very effective funnel.
Have an adult help or supervise you in this step
Step 3. Use the top of the bottle to make a funnel
Take the cut part of the bottle, turn it over, and put it back on the bottle. This means that the top of the bottle should point towards the inside of the bottle (remove the cap). In this way, the water will be able to flow into the rain gauge. Secure the funnel with duct tape.
Part 2 of 3: Calibrate the instrument
Step 1. Add a layer of sand a little over 1⁄2 inch (1 cm) to the bottom of the bottle
Adding sand to the bottom of the bottle will give it some weight so it won't tip over. It will also give you a level surface to measure the water (the bottoms of most bottles are uneven).
You can use any type of sand. If you pick it up on the bank of a river or on the beach, make sure there are no debris such as herbs, sticks, shells or stones. You can also buy sand at a local hardware store
Step 2. Saturate the sand with water
Add enough water to cover the sand completely. The amount of water needed to fill all the gaps between the sand particles and cover the top of the sand is called the saturation point. Use a marker to mark the saturation point on the outside of the bottle.
Step 3. Make a scale on the bottle
From the saturation mark, measure the bottle and make marks every centimeter or every inch (if you prefer). You can also make marks between these lines to designate millimeters or fractional inches (such as 1/2, 1/4, and 1/8 of an inch, etc.). Put clear tape over the marks to protect them from the elements.
- You can also use clear tape to attach a ruler to the bottle.
- You can also mark the bottle in centimeters or millimeters on one side and inches on the other.
Part 3 of 3: Using the instrument
Step 1. Place the bottle in a hole on the outside
Typically, rainfall is measured at ground level. This means that you will have to dig a hole deep enough to fit the bottle. The top of the bottle should be flush with the ground.
Step 2. Let the bottle collect the rain
Leave the bottle uncovered. When it rains, the rainwater will go into the bottle. This will allow you to record the amount of rain that has fallen that day.
Step 3. Record the readings
Take the bottle out of the hole and see how much water has collected. Record the amount of rain collected. In this way, you can put the rain gauge back in the same place and collect the water from the next rain. Over time, you will be able to graph the amount of rain that has fallen in your area.
Keep in mind that these readings will differ based on the size of the bottle you use. Any bottle will differ from the official rain gauge used by meteorologists
- It also calculates the speed and direction of the wind, as well as the atmospheric pressure.
- Try to install the rain gauge when there is a forecast of rain.
- Use a wide-mouth bottle to collect more water.