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Theoretical limit to how hard it can rain (reddit.com)
106 points by soundsop on June 18, 2011 | hide | past | favorite | 13 comments


That's not very useful limit.

First, the hottest temperature recorded was probably in some place like Death Valley, so the humidity was probably very low. Thus there isn't nearly as much water is the air as indicated by the saturation pressure.

Second, if you somehow did manage to have hot air fully saturated with water mix with very cold air, the hot air has much higher heat capacity (due to all the water in it). One cubic meter of -83C air has a mass of roughly 1kg, so a heat capacity of 1kJ/K. The heat of vaporization of water is about 2000kJ/kg, so by the time you'd condensed about 70g of that water, the cool air would have heated up to +55C (and that ignores the heat capacity of the hot air and the water).

So it's pretty safe to say, yes it's a limit but not a very useful limit as it is so far above what's physically possible.


While not close to the theoretical maximum, the observed records are, nonetheless, stunning.

1 min - 31.2mm (1.23")

60 min - 305mm (12.0")

12 hr - 1.825 m (45.0")

24 hr - 2.467 m (97.1")

72 hr - 3.929 m (154.7")

96 hr - 4.869 m (191.7")

12 month - 26.47 m (1042")

source (http://wmo.asu.edu/#global)

Almost all of the records come from La Réunion ( http://en.wikipedia.org/wiki/R%C3%A9union ), which is an island straight east of Madagascar. If you're from the US, think of the Hawaiian islands but in the Indian Ocean. Significantly, the island has peaks that rise up to 3,070 meters (10,070 ft).

I am guessing large Indian Ocean cyclones get going and then just run slap into this vertical peak in the middle of the ocean. Then, rain. Rain for apparently days straight.


Not nearly as dramatic as Réunion, but I've personally seen 900mm (35.4") of rain in one day. It was August 31, 2002 in the East Coast of South Korea. It felt like a reenactment of the Biblical deluge or something. Really scary stuff.


Straight east of Madagascar.


fixed


Can there be any non-technical response to this that isn't roughly equivalent to "Awesome"?

Meh. I love the depth of the answer, and what an awesome visualization :D


I share your sentiment. The whole waterfall from the sky imagery got me. Eye opening. Sometimes you can find a gem like that on Reddit. Sometimes.


I think I prefer to get my Reddit filtered. Like this.


There's a Reddit for that... http://www.reddit.com/r/bestof/top/


However, that also tends to promote funny threads, in-jokes, etc.

Still better than the average front page for sure, but don't expect it to be the reddit of three years ago.



That would make a great simulation to watch.


Alright, we need some fans and a massive heat pump, let's make this happen.




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