You would heat up the planet a fair bit. All that kinetic energy would be turned into thermal energy when it hit the surface. And that is a whole lot of mass. I’m not sure if it would rise to the level of an extinction level event or not, but it wouldn’t be fun.
Would happen if it rained for 40 days and 40 nights? Here in Arizona you’d have 10 idiots a day trying to drive through flooded washes.
Eight months of solid rain last season! Probably even longer than that. I was glad to see it go.
If it rained for 40 days and nights a lot would depend on how much rain came down, per second, or minuet. To cover the entire earth and allow a boat to sit on top of a mountain like Ararat, it would take quite a downfall! Then the water could only evaporate because there would be no place for it to run off. The amount of water that would cover the earth in that way for nearly a year,(as the Noah’s story tells, would kill off all the vegetation,and even trees could not take that much water for that many days. It would also seem that the oceans would not be as salty so many of the sea animals would also die. That is how it would seem to me, I am not an authority on it but I am skeptial.
Depends on the river or stream. Generally speaking, if the time of concentration at your point of reference is smaller than 40 days, you would expect to have some flooding. If it is greater than 40 days, you wouldn’t.
I’ve never heard of any times of concentration greater than 40 days. Usually, they’re measured in hours. However, I suppose you could get some weird situations on major rivers with large watersheds, what with it raining everywhere, as the OP posited.
In any event, if the peak flow is high enough, you could certainly get flooding even if the time of concentration exceeds that of the storm event.
Or minutes, even. 
Yes I was thinking of major rivers. Let’s see … 3600 seconds per hour for 24 hours per day for 40 days is 3,456,000 seconds. At 2 fps that’s [del]1,728,000 feet or 327 miles (if my math’s right)[/del] wrong. 1,309 miles. About 60 rivers world-wide are 1,309 miles long or longer.
Given the large variation in hydrologic situations around the globe, there would be areas with efficient drainage such that a steady rain wouldn’t present a problem. As I mentioned in the other thread, there are so many variables (watershed slope, shape, antecedent moisture condition) that it’s difficult to predict what would happen with the OP’s scenario.
If the entire earth was covered with 29,000 feet of water which would mean that Mt. Everest was covered, then evaporated to 15,000 feet( the height of Ararat), then that would mean there was at least 15,000 feet of water for the Ark to rest on top of that. The evaporation of the water itself would cause the Ark to be so full of humidity the people or animals would have a hard time breathing and of course so many of the insects etc. would really be a problem, then the swimming back to their own countries would be a feat in it self. Plus living that way for nearly a year would not be a very pleasant way to live; imagine the stench!!
How did 94 inches of rain turn into 29,000 feet?
This is based on Noah’s flood, and the Bible describes the waters as covering the highest mountain, i.e. Everest, which is 29,000 feet high (to two significant figures).
Thank you BigT. I reckon Noah’s flood had a much greater intensity or total rainfall than what’s been assumed here.