system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: How is rain measured in cm/mm?
gpt
If you leave a cylindrical bucket outside and it rains a half an inch, then there will be a half an inch of water in the bucket afterwards. A larger bucket will catch more rain, but it will also take more rain to fill it up. Measuring the vertical depth of the water is a consistent measurement no matter what size bucket you use, so it is the ubiquitous standard for reporting rain amounts.