Measuring Rainfall

You will need:

• a large plastic soft drinks bottle
• scissors
• a ruler
• a waterproof marker pen (or coloured sticky tape)
• a heavy flower pot
• a notepad and pencil (to record the results)

With the help of an adult, carefully cut the top off the plastic bottle with the scissors.

Turn the top upside down and wedge it in the bottle to form a funnel. (If necessary, use sticky tape to hold the top of the bottle in place).

Using a ruler, measure out a scale (in millimetres) on a piece of paper. Either stick this to the side of the bottle, or use the marker pen to mark out the lines instead. Alternatively, cut the coloured tape into strips and stick them a certain distance apart (eg: 10 mm) up the side of the bottle. Make sure that whatever you use, it is waterproof!

To prevent the rain gauge from blowing over, place it outside in a heavy flowerpot. Alternatively, you could dig a hole in the ground for it to stand in. Make sure the rain gauge is placed in an open area. If it is near any trees or buildings, extra water could drip into it and your measurements will not be accurate.

Now you are ready to record how much rainfall is received over a certain time. Check the rain gauge every day, or once a week if you prefer, and record how much water is in the bottle. Use the scale or the marks on the side of the bottle to help you.

Remember, if you are only taking measurements once a week, make sure your rain-gauge does not overflow in between if you get a lot of rain. You could always use a measuring cylinder to store the week’s rain before you measure it.

Each time you measure the water, plot the results on a graph or in a table. You could print out the table below to help you if it is easier. Make sure you could draw it yourself as well though.

Weekly Rainfall chart

Now you know about rainfall - and how to measure it - let's move on to find out about another form of precipitation - snow.