Because of the thread about the water contained in ringwoodite in the mantle, which has creationists wondering if this explains where all the water went after the Flood, I got curious about how much water would have been contributed to the depth of the Flood waters by the forty days and forty nights of rainfall that occurred at the beginningapart from that contributed by the fountains of the deep which would have been considerable but incalculable as far as I know.
So I looked around for information on measuring rainfall and found this Weather Underground blog the most informative for my purposes:
The rainfall at the beginning of the Flood is supposed to have been worldwide and continuous and very heavy. How heavy I don't know, but there is one extremely heavy rainfall recorded for the US at over an inch a minute in Unionville, Maryland according to this blog, so I simply computed from an inch a minute and got some pretty hefty numbers.
An inch a minute all over the earth would be Sixty inches an hour or five feet an hour Ten feet in two hours, twenty in four, forty in eight, 120 feet in 24 hours. Or 4800 feet by the end of the forty days and nights of the rainful. That would pretty well cover the pre-Flood mountains which weren’t anywhere near as high as the mountains we have now that were formed by tectonic force.
Please correct my arithmetic if necessary.
Since that's an extreme rate of rainfall, although for all I know it's close to what actually happened, I figured I should consider a lower rate as well. An inch an hour would still be a heavy rain as we know it, so I computed that too. That's of course 24 inches or two feet in a 24-hour day. That's 60 feet in a month or 80 feet by the end of the forty days and nights.
Something between the two rates might be the best guess.
This may be a rather thin topic for a thread but I'm not sure how to flesh it out.