DIY - Model 2
Measuring rain water volume
This is an interesting design for collecting rain water. In this design we have used one small bottle (1 litre) and a thermal cover bag for it. This is kind of cover is available in the stores where material for school going children is sold. In this design we have used a discarded bag. This bag (with bottle inside it) can slide into 2 liter pet bottle with its bottom part cut. We then drilled hole in the cap of the small bottle to fit in the funnel. We sealed the funnel to the cap using M-seal.
We found a long (waterproof) wooden plank (one can use a rod or similar material). The plank was about 8 mm thick, 4 inch (10 cm) wide and about 5 feet (1.5 m) long (tall). We used the other 2 liter pet bottle and cut off its bottom part and fixed it upside down to the this plank at one end.To do this we made two matching holes in the plank and the bottle and tied the bottle using nylon rope. Then the first bottle is slide into this bottle.
Our rain gauge is now ready. We then placed it at some convenient place. The rain water collecting bottle easily comes out of the bigger bottle. We can now uncap the funnel and either collect water in a baker and measure volume of the water collected or measure it directly.
A suggestion: If you do not have a good measuring cylinder at hand you can use two small bottles. On one bottle cap attach a funnel. Now one bottle can be used for collecting the rain water and other transporting. Now one alternate the bottle for collecting the rain water and for transporting.
This idea can be used for collective class room exercise. Students can be asked to set up their own rain gauges at home and bring the collected rain water to the school for measuring volume.
Some of the observations taken may not be as good as those taken by professional observatories but the aim here is to learn to do scientific experiments and take observations, as accurately as possible.