# Why Is Rain So Surprisingly Gentle? **URL:** \ **Category:** Factual Questions\ **Created:** [March 10, 2009, 2:32am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912 "2009-03-10T02:32:03Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Jim\_B](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jim_b/32/4338_2.png) [@Jim\_B](https://boards.straightdope.com/u/Jim_B)\ **Post date:** [March 10, 2009, 2:32am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/1 "2009-03-10T02:32:03Z")
So I am 8 years old. And my family and I are taking a vacation to the Sears Tower in Chicago, IL. It is a purported 110 stories tall. And the whole trip over, all my cousin and I can talk about is throwing some solid object over the tower. My parents tell me they would never allow that, since a solid object thrown over a place so high would come down to earth with the force of a bullet. Finally we reach a compromise. My parents tell me they will allow me to _spit_ over the Sears Tower. But they also warn me spit at that level will just evaporate before it reaches the ground. (Long-story-short, we finally reach the Sears Tower, and go to the top, only to find it is _completely enclosed_. What a bummer;).) Anyways, it is years later. And something has perplexed me all these years. Rain clouds are probably hundreds of feet in the air. Probably even taller than the Sears Tower, no? Yet rain doesn’t come down with the force of bullets. Why not? Thank you in advance to all who reply:) ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 10, 2009, 2:41am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/2 "2009-03-10T02:41:44Z")
_[Terminal Velocity.](http://en.wikipedia.org/wiki/Terminal_velocity)_ ---
**Author:** ![Drum\_God](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drum_god/32/44_2.png) [@Drum\_God](https://boards.straightdope.com/u/Drum_God)\ **Post date:** [March 10, 2009, 2:41am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/3 "2009-03-10T02:41:51Z")
Whoa. A first, I was struck by an 8-year-old using the word “purported”. Reading further, I realized that you _were_ eight years old, but _now_ you’re somewhat older. Anyway, it doesn’t matter how high above the surface of the Earth a falling object begins its fall. It eventually reaches terminal velocity and will not go faster. It can fall from hundreds of feet, the top of the Sears Tower, or miles up. Once terminal velocity is reached, that’s it – it goes no faster. So, the velocity is terminal, but the impact of a raindrop on your head is not terminal for you. ---
**Author:** ![seodoa](https://avatars.discourse-cdn.com/v4/letter/s/4af34b/32.png) [@seodoa](https://boards.straightdope.com/u/seodoa)\ **Post date:** [March 10, 2009, 2:53am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/4 "2009-03-10T02:53:31Z")
It’s also worth noting that rain’s terminal velocity is so high because raindrops are not very aerodynamic. They flatten as they fall and do not form that tidy teardrop shape we are all so familiar with. More [info](http://www.ems.psu.edu/~fraser/Bad/BadRain.html). For more information about rain and terminal velocity, look [here](http://www.grow.arizona.edu/Grow--GrowResources.php?ResourceId=146). ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [March 10, 2009, 7:43am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/5 "2009-03-10T07:43:02Z")
> [@Drum\_God](#): > > Anyway, it doesn’t matter how high above the surface of the Earth a falling object begins its fall. It eventually reaches terminal velocity and will not go faster. It can fall from hundreds of feet, the top of the Sears Tower, or miles up. Once terminal velocity is reached, that’s it – it goes no faster. With the proviso that terminal velocity is dependent on fluid density and gravitational force, which are not constant through the atmosphere. At altitudes of a few miles, it makes little difference. But falling from really really high an object will have a higher ‘terminal velocity’ since air density drops off faster than gravity. This doesn’t contradict the basic point. Once it gets low enough the object does reach the same terminal velocity as if it fell from the lower height (not necessarily exactly since it must lose some of the energy it had when it was falling faster higher up). ---
**Author:** ![Anaglyph](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Anaglyph](https://boards.straightdope.com/u/Anaglyph)\ **Post date:** [March 10, 2009, 7:53am UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/6 "2009-03-10T07:53:30Z")
Also, in contrast to hailstones, if raindrops get too big they fall apart during their fall ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [March 10, 2009, 12:08pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/7 "2009-03-10T12:08:29Z")
The sears tower observation area is enclosed. Mostly I’d say to protect people on the ground from falling pennies and bodies killing them. ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [March 10, 2009, 12:17pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/8 "2009-03-10T12:17:42Z")
> [@Harmonious\_Discord](#): > > The sears tower observation area is enclosed. Mostly I’d say to protect people on the ground from falling pennies and bodies killing them. A penny wouldn’t kill anybody. They did this on Mythbusters. A penny at terminal velocity will sting like a bitch, but no deaths. I doubt falling bodies was a consideration. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [March 10, 2009, 2:16pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/9 "2009-03-10T14:16:50Z")
> [@Harmonious\_Discord](#): > > The sears tower observation area is enclosed. Mostly I’d say to protect people on the ground from falling pennies and bodies killing them. Also, probably to protect the deck observers from high winds. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [March 10, 2009, 2:43pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/10 "2009-03-10T14:43:03Z")
> [@Snarky\_Kong](#): > > A penny wouldn’t kill anybody. They did this on Mythbusters. A penny at terminal velocity will sting like a bitch, but no deaths. I doubt falling bodies was a consideration. Was it a new lighter penny or the older heavier copper penny? ---
**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\ **Post date:** [March 10, 2009, 3:42pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/11 "2009-03-10T15:42:05Z")
> [@Harmonious\_Discord](#): > > Was it a new lighter penny or the older heavier copper penny? The old copper penny was only ~23% heavier than the new one, so I doubt it would make too much difference anyway. ---
**Author:** ![davekhps](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@davekhps](https://boards.straightdope.com/u/davekhps)\ **Post date:** [March 10, 2009, 3:51pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/12 "2009-03-10T15:51:55Z")
> [@Snarky\_Kong](#): > > A penny wouldn’t kill anybody. They did this on Mythbusters. A penny at terminal velocity will sting like a bitch, but no deaths. I doubt falling bodies was a consideration. I would guess that falling bodies was probably \*very much \*a consideration-- the (then) tallest building in the world with an open observation deck would be a suicide magnet. Well, that, and the wind turbulence generated by an open-air deck probably wouldn’t be much fun for the tourists. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [March 10, 2009, 4:09pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/13 "2009-03-10T16:09:42Z")
> [@Drum\_God](#): > > So, the velocity is terminal, but the impact of a raindrop on your head is not terminal for you. What makes some raindrops hit so much harder than others? Wouldn’t they have all hit this terminal velocity by the time they fall from cloud height? ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [March 10, 2009, 4:14pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/14 "2009-03-10T16:14:17Z")
Wind. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [March 10, 2009, 4:24pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/15 "2009-03-10T16:24:58Z")
If it were true that small objects falling from a great height had the force of a bullet we would all be in some serious trouble during a hail storm. While large size hail can do some considerable damage (golf ball size and larger), the bullet size stuff is far from lethal. (And how were you going to attempt to throw something “over” the tower?) ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [March 10, 2009, 4:38pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/16 "2009-03-10T16:38:46Z")
> [@Hampshire](#): > > If it were true that small objects falling from a great height had the force of a bullet we would all be in some serious trouble during a hail storm. > While large size hail can do some considerable damage (golf ball size and larger), the bullet size stuff is far from lethal. > > (And how were you going to attempt to throw something “over” the tower?) He meant over the parapet/railing. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [March 10, 2009, 6:21pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/17 "2009-03-10T18:21:27Z")
> [@Lemur866](#): > > Wind. Straight down? What about when it just pours really heavily? It’s wind? ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [March 10, 2009, 6:28pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/18 "2009-03-10T18:28:34Z")
Well, the more water falling the heavier the rain is. I thought you meant individual raindrops hitting harder. Raindrops have terminal velocity depending on their size, and so larger drops have a higher terminal velocity. But large drops break up into small drops, so there’s a maximum drop size depending on how much water is falling. Aside from that, terminal velocity is velocity relative to the air, not to the ground. If a given mass of air moves up or down or sideways it will carry along any raindrops in that mass of air. So during heavy winds you can add a sideways vector to the speed of the raindrop relative to your face. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [March 10, 2009, 6:34pm UTC](https://boards.straightdope.com/t/why-is-rain-so-surprisingly-gentle/488912/19 "2009-03-10T18:34:51Z")
Cool, thanks!