What's the weight of all that rain?

[Thankyou4calling]

After a lovely day yesterday I left my car out with the roof down overnight only for it to start raining at about 4am, interior was soaked but there you go.

It got me thinking. If it rained for say 2 hours over an area of 100 square miles, pretty heavy say 10mm how much actual rain would fall?

Would it fill an Olympic swimming pool? How many?

And how much would it weigh?

God knows why but I was just wondering.

Thanks for replies.

[Thankyou4calling]

Thanks for the replies. I'm going to read them again to see if I've got a definitive answer but either way that's a lot of rain in weight and volume terms.

[Thankyou4calling]

cv01jw said:

Assuming 100 square miles is taken as 10 miles by 10 miles (as opposed to 100 by 100), then the catchment area is 16.09km x 16.09km = 258.89km². This is 258,890,000m².

Rainfall of 10mm (0.01m) over this catchment would generate 2,588,900m³ of water.

An olympic pool taken as 25m x 50m x 2m will hold 2,500m³ of water, therefore the rainfall above would fill 1,035 pools.

To put these figures into another perspective, 10mm of rainfall over 2 hours is not particularly high. An industry standard 'typical' rainfall event used for fag-packet type calculations would use 50mm per hour.

When undertaking detailed designs of drainage systems the actual rainfall used varies depending on lots of factors, but peak intensities in excess of 200mm per hour are not uncommon.

I think your calculations are right BUT.

50mm of rain in an hour is nearly two inches. London, as an example gets two inches A MONTH!! So in an hour that's an absolute deluge.and far from typical.