# How heavy would it have to rain to flood the Earth in 40 days? **URL:** \ **Category:** Factual Questions\ **Created:** [May 25, 2019, 6:24am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494 "2019-05-25T06:24:19Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 6:24am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/1 "2019-05-25T06:24:19Z")
Cast your beliefs and disbeliefs to the side for the purpose of this thread, please. How much rain would have to fall in a forty day(and night) period to actually flood the Earth and cover the highest mountain 40 cubits(approximately 60 feet)? ---
**Author:** ![pmwgreen](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@pmwgreen](https://boards.straightdope.com/u/pmwgreen)\ **Post date:** [May 25, 2019, 6:52am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/2 "2019-05-25T06:52:54Z")
You want to fill the volume of a hollow spherical shell going from sea-level to the highest mountain, (less the volume already occupied by land). Is there an average height of the land above sea-level we could use to estimate the volume of land surface? And if the sun exploded at the same time, would the seas then boil at a lower temperature, being at a higher altitude? ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 6:55am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/3 "2019-05-25T06:55:36Z")
> [@pmwgreen](#): > > You want to fill the volume of a hollow spherical shell going from sea-level to the highest mountain, (less the volume already occupied by land). Is there an average height of the land above sea-level we could use to estimate the volume of land surface? And if the sun exploded at the same time, would the seas then boil at a lower temperature, being at a higher altitude? Let’s leave the “sun exploding” bit for another thread, please? ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [May 25, 2019, 7:10am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/4 "2019-05-25T07:10:38Z")
A quick calculation gives the volume that has to be filled as 3.73217E+17 cubic feet. But that doesn’t help all that much as far as rainfall. It is easier to see that each spot on the Earth would get 60 / 40 or a foot and a half of rain per day. That’s after the sewers back up, of course. The real problem seems to be that calculating the energy of the rain after falling from the supposed water above the Earth would more or less melt everything. Problem number 3 is where did the water go after the flood? ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 7:13am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/5 "2019-05-25T07:13:46Z")
> [@Voyager](#): > > A quick calculation gives the volume that has to be filled as > 3.73217E+17 cubic feet. > But that doesn’t help all that much as far as rainfall. > It is easier to see that each spot on the Earth would get 60 / 40 or a foot and a half of rain per day. > That’s after the sewers back up, of course. > The real problem seems to be that calculating the energy of the rain after falling from the supposed water above the Earth would more or less melt everything. > Problem number 3 is where did the water go after the flood? Problems #2 and #3 are for another thread, please-I just want an answer to problem #1. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [May 25, 2019, 7:36am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/6 "2019-05-25T07:36:51Z")
> [@Czarcasm](#): > > Cast your beliefs and disbeliefs to the side for the purpose of this thread, please. How much rain would have to fall in a forty day(and night) period to actually flood the Earth and cover the highest mountain 40 cubits(approximately 60 feet)? This is such an elementary math problem that I wonder if there is another purpose for the question. Mt. Everest is 29,029 ft. Divide that by 40 days, 24 hours per day and 60 minute per hour. I get 6” of rain per minute. A quick google search shows the record rainfall in one minute is 1.22”. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 7:42am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/7 "2019-05-25T07:42:49Z")
> [@TokyoBayer](#): > > This is such an elementary math problem that I wonder if there is another purpose for the question. > > Mt. Everest is 29,029 ft. Divide that by 40 days, 24 hours per day and 60 minute per hour. I get 6” of rain per minute. > > A quick google search shows the record rainfall in one minute is 1.22”. No ulterior motive-I just wanted an answer to the question I asked. Thank you. ---
**Author:** ![UnwittingAmericans](https://avatars.discourse-cdn.com/v4/letter/u/d9b06d/32.png) [@UnwittingAmericans](https://boards.straightdope.com/u/UnwittingAmericans)\ **Post date:** [May 25, 2019, 10:27am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/8 "2019-05-25T10:27:49Z")
> [@Voyager](#): > > Problem number 3 is where did the water go after the flood? It doesn’t go anywhere, you have Waterworld. Some evaporates and eventually Everest becomes Dryland. And for awhile, you can climb the highest mountain on earth in like 10 minutes. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [May 25, 2019, 11:08am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/9 "2019-05-25T11:08:54Z")
From this, it could have been a light sprinkle, as there was a second source of water, even a case for a 3rd source could be made: > [@Gen 7](#): > > 11 In the six hundredth year of Noah’s life, on the seventeenth day of the second month—on that day **all the springs of the great deep burst forth** , and the floodgates of the heavens were opened. 12 And rain fell on the earth forty days and forty nights. In Gen 1 God divided the water above and below, it appears that both were being used here, if not 3 sources (underworld, our world, and from the heavens). Gen 2:5 could be said to make rain that 3rd category of water as it was seperate from the division of waters below and above. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 11:16am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/10 "2019-05-25T11:16:08Z")
> [@kanicbird](#): > > From this, it could have been a light sprinkle, as there was a second source of water, even a case for a 3rd source could be made: > > In Gen 1 God divided the water above and below, it appears that both were being used here, if not 3 sources (underworld, our world, and from the heavens). Gen 2:5 could be said to make rain that 3rd category of water as it was seperate from the division of waters below and above. Just interested in how hard it would have to rain in forty days to cover the highest mountains. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 25, 2019, 11:33am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/11 "2019-05-25T11:33:38Z")
Slightly less than 362.5 inches per hour, everywhere on earth, non-stop, for the entire 40 days. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 25, 2019, 11:36am UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/12 "2019-05-25T11:36:23Z")
> [@TriPolar](#): > > Slightly less than 362.5 inches per hour, everywhere on earth, non-stop, for the entire 40 days. Is there space between the raindrops at that rate? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 25, 2019, 12:15pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/13 "2019-05-25T12:15:24Z")
> [@Czarcasm](#): > > Is there space between the raindrops at that rate? Yes. It’s only accumulating at 1/10 of an inch per second. That means a drop with a volume of 1/10 of a square inch has to hit the ground or water surface per second. If my math is correct (which is highly unlikely), assuming spherical drops, that’s somewhere around a .31 inch diameter drop per second. Plenty of space in between them. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [May 25, 2019, 12:42pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/14 "2019-05-25T12:42:15Z")
And what the hell kind of clouds could supply the planet with that much rain? ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [May 25, 2019, 12:57pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/15 "2019-05-25T12:57:41Z")
> [@panache45](#): > > And what the hell kind of clouds could supply the planet with that much rain? Heavenly? ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [May 25, 2019, 1:00pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/16 "2019-05-25T13:00:03Z")
That much water will definitely trigger earthquakes and effect the tectonic plates. Be ready for giant tsunamis. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [May 25, 2019, 1:37pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/17 "2019-05-25T13:37:46Z")
> [@am77494](#): > > That much water will definitely trigger earthquakes and effect the tectonic plates. Be ready for giant tsunamis. Not to mention make the ark top-heavy. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 25, 2019, 1:55pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/18 "2019-05-25T13:55:13Z")
Given the entire planet is being rained upon (thus nowhere for air driven down by the falling dropplets to go), and the rain is falling from some height, I wonder what the air pressure increase we would see on the ground would be. There is a quite significant density of water droplets in the air, so I would imagine the pressure created could be reasonably significant. ---
**Author:** ![Arrogance\_Ex\_Machina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/arrogance_ex_machina/32/192_2.png) [@Arrogance\_Ex\_Machina](https://boards.straightdope.com/u/Arrogance_Ex_Machina)\ **Post date:** [May 25, 2019, 2:08pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/19 "2019-05-25T14:08:41Z")
> [@am77494](#): > > That much water will definitely trigger earthquakes and effect the tectonic plates. Be ready for giant tsunamis. Once there’s no more beaches because of the flood the tsunamis won’t do much. Probably the least of our worries at that point of course. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [May 25, 2019, 2:14pm UTC](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494/20 "2019-05-25T14:14:17Z")
> [@Francis\_Vaughan](#): > > Given the entire planet is being rained upon (thus nowhere for air driven down by the falling dropplets to go), and the rain is falling from some height, I wonder what the air pressure increase we would see on the ground would be. There is a quite significant density of water droplets in the air, so I would imagine the pressure created could be reasonably significant. [13,000 PSI](http://www.talkorigins.org/faqs/canopy.html). [Next page](https://boards.straightdope.com/t/how-heavy-would-it-have-to-rain-to-flood-the-earth-in-40-days/834494.md?page=2)