Sometimes it's good to know how much it has rained; a rain gauge will help you find this out. There are lots of different rain gauges which can be purchased from shops however these can be rather expensive.
Step 1 - Cutting the Bottle
Start by cutting the top off the 2 litre plastic bottle. It's important that the plastic bottle has a constant diameter so that it's easy to measure the volume of rain which has fallen. You should cut a quarter off the top of the bottle so that you get a constant cylinder. Try to cut this smoothly. You may want to wrap some waterproof tape around the cut edge so that it won't cut you.
Step 2 - Making a Funnel
Turn the top of the bottle (which has just been cut off) upside down and place it into the cylinder. You can use tape or paperclips to hold this in place. Again you might like to use something to cover the sharp edges.
Step 3 - Locating the Rain Gauge
When locating the rain gauge you need to choose a location where the rain is not restricted. This means that you should be careful not to locate the gauge against trees or walls. Anything which can interfere with the amount of water will make the gauge much less accurate than it would otherwise be.
Spend some time deciding where to site the rain gauge and you should choose the best location to get the most accurate result.
Step 4 - Support
Your plastic bottle will not be heavy enough to stand up by itself. That's why you will find it much easier if you stand it in a bucket full of sand. Bury the bottle in the sand to provide as much support as possible. Make sure that the bottle is level as this will make the readings much more accurate.
Step 5 - Measuring
To measure the rain in your rain gauge you simply pour the contents out into a measuring jug. You will need to measure the contents of the rain gauge on a daily basis at approximately the same time every day to get an accurate result.
You will get much better results if you put your rain gauge in a cool place so that the water isn't as likely to evaporate and distort the readings.
The rain gauge can also measure snow and hail but to do this you should remove the funnel and also wait for the ice to melt before measuring the volume of precipitation.
Step 6 - Improvements
A rain gauge dip stick could be made with a piece of doweling so that you can easily find out how much rain has fallen. Alternatively you could mark out measurements on the bottle itself so that there is no need for the measuring jug. Whichever option you choose, you will need to empty it on a regular basis.