The depth of rain remains the same related to diameter/ open area, but more accuracy will be experienced with a larger diameter.
For best results, a funnel and a smaller container can be used. By working out the funnel opening area and the container area and dividing the funnel area by the container area, you come up with a divisor you can use on the height of water in the container. This divides error by the same factor.
No. The diameter must be large enough for a raindrop to enter the top AND fall/slide to the bottom. I'd think about 5 mm would be the minimum.
The depth must be large enough to hold a reasonable amount of water, but short enough to be easily measured and drained. From 12 to 60 cm seems about right to me.
Yes as long as the sides are straight and square to the bottom.
Read this link for rain gauge......
http://www.infoplease.com/cig/weather/me...
