Rain Gauge Investigation

Objectives

• Describe what a rain gauge is and how it works.

Materials

• Per Student:
  750 mL plastic container (yogurt container, jar or other, opening should be same size as body)

• Per Class:
  5  of 60 mL measuring cups (1/4 cup)
  5 buckets of water
  10 waterproof markers

  Optional:  5 of 5 ml ( 1 tsp) and 5  of 15mL ( 1TSP) Tsp measuring spoon for a more detailed level of precipitation measurement &  smaller plastic containers ( 350 ml)

Key Questions

• Where is a good place to set up the rain gauge? In the open? Under an overhanging roof? Unger a tree?
• What could effect rainfall into the gauge? What could increase or decrease it an effect accuracy of the results?
• What role might evaporation play over time?

What To Do

Set-up

1. Set up 5 tables with a  measuring cup (60mL = 1/4 cup), 2 waterproof markers and 1 bucket of water at each table.
2. Divide the class into 5 groups. One group will work at each table.
3. Hand out a plastic container to each student.

Instructions

1. Have students take turns to fill the 60 ml (1/4 cup) measuring cup with water from the bucket. Then, have the students pour the water into their own container. Repeat until everyone in their group has filled their containers.
2. Have each student mark the water level with a marker on the side of their container, and label the water level at 60 mL.
3. Once everyone in the group has poured, marked, and labeled the 60 mL amount, have students repeat steps 1 and 2, increasing the amount each time by one measuring cup worth. The marks on their container should read 60 mL, 120 mL, 180 mL, 240 mL, 300 mL, etc.
4. Once each student reaches the top, they should empty the rain gauge water back into the bucket on their table.
5. Finally, students can place their rain gauge outside and record how much rain is received each day/week/month.

NOTE: To accurately measure precipitation over time it is best to record observations after EVERY  rainfall. This will keep loss of water to the air via evaporation from effecting results.
For this reason you may wish to start with markings of less than 60 mL, like 5ml (1 teaspoon = 1tsp), 15mL (1 Table spoon = 1Tsp), ect.

Dry variation:

Preparation

1. Prepare one container with the volume markings already labelled. Substitute the measuring cup and water bucket with this template container.

Instructions

1. Have student use the template container to mark the same measurement marks on their own containers.

          NOTE: for this to work all Rain Gauge containers much be identical in shape and size.

Extensions

• Calculate the area of the circle for the container used as the rain gauge. Measure across the widest part of the container opening, then divide by 2 to get the radius. Area is equal to 3.14 x radius squared (A = pi r^2) This will allow students to record the rainfall over a certain arean over a certain time.
• Measure the rainfall for an entire month, recording daily rainfall on a chart. Plot the rainfall chart on a graph, and compare week to week (or extend for a season or school year).
• What role might evaporation play over time? How might it effect measurement of water left to stand in the rain gauge?
• How might different kinds of precipitation ( rain, sleet, snow, hail) effect the measurements taken?
• Check the level of the Metro Vancouver reservoir — is the curve going up or down? What does that mean?
• Make a large rainwater catchment system for your school or home. Attach it to your eavestroughs or downspouts and see how much water you can collect.

Other Resources

MetroVancouver |Watersheds & Reservoirs

MetroVancouver | Exploring Our Watershed PDF

MetroVancouver | Reservoir Levels & Water Use