How do you read a rain gauge?
Glad you asked...
When rain collects in your rain gauge you may get confused as to how to read it. When you look at the measuring tube you will see a concave sort of bubble. The proper way to read this is to use the number that is at the bottom of the the concave or U shaped bubble. When the measuring tube is completely filled it will hold one inch of water.
SweetLass72, Shopping Expert
Then again, this answer might help you...
To read a rain gauge you will have to have a measuring tube in the gauge. Choose the line that is closest to the bottom of the meniscus or lowest point of the water in the tube. These lines measure tenths and hundredths of an inch of rain.
Chatague, Shopping Expert