Hello, I wasn't sure exactly where to put this thread. Figured this was the most relevant section. Anyway, I wanted to know what exactly do meteorologists mean when they say that a region will receive 5mm or 10mm of rain during the evening. I read this wiki page http://en.wikipedia.org/wiki/Precipitation_(meteorology)#Measurement but it is all still clear as mud. I thought there was a relationship between the mm value given and the volume of water that would land over a given area but i am not sure. Can someone please clarify? Is there anything straightforward like every square meter will get half a liter of water over 5 hours? or something to that effect? Thanks.