A rain gauge is a simple tool that measures how much rain falls in one place over a period of time. You can make one from a clear plastic bottle, a ruler, and a few basic classroom supplies. This project helps students practice careful measuring, data recording, and weather observation.
It also shows how small daily measurements can reveal patterns in local weather.
Key Facts
- Rainfall depth is measured as the height of collected water, often in millimeters or inches.
- 1 cm = 10 mm.
- Rainfall rate = rainfall depth ÷ time.
- A rain gauge should be placed in an open area away from roofs, trees, and sprinklers.
- Read the water level at eye height to avoid parallax error.
- Total rainfall over several days = day 1 rainfall + day 2 rainfall + day 3 rainfall + ...
Vocabulary
- Rain gauge
- A rain gauge is an instrument used to measure the amount of rain that falls in a specific place.
- Precipitation
- Precipitation is water that falls from the atmosphere, such as rain, snow, sleet, or hail.
- Millimeter
- A millimeter is a small unit of length often used to measure rainfall depth.
- Data table
- A data table is an organized chart used to record measurements and observations.
- Meniscus
- The meniscus is the curved surface of water in a container, and measurements should be read at the bottom of the curve.
Common Mistakes to Avoid
- Putting the gauge under a tree or roof is wrong because extra drips or blocked rain can change the measurement.
- Starting the scale above the bottom of the bottle is wrong because the first bit of water would not be counted correctly.
- Reading the water level from above or below is wrong because it can make the measurement look higher or lower than it really is.
- Forgetting to empty the gauge after recording is wrong because the next day's rain will be added to the old water.
Practice Questions
- 1 A rain gauge shows 18 mm of rain after 6 hours. What was the average rainfall rate in mm per hour?
- 2 A student records 12 mm on Monday, 7 mm on Tuesday, 0 mm on Wednesday, and 21 mm on Thursday. What is the total rainfall for the four days?
- 3 Two students use identical bottle rain gauges, but one places the gauge under a tree and the other places it in an open field. Explain which measurement is more reliable and why.