# Clouds.. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [September 8, 2001, 4:27am UTC](https://boards.straightdope.com/t/clouds/80355 "2001-09-08T04:27:14Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![TheNewbie](https://avatars.discourse-cdn.com/v4/letter/t/db5fbb/32.png) [@TheNewbie](https://boards.straightdope.com/u/TheNewbie)\ **Post date:** [September 8, 2001, 4:27am UTC](https://boards.straightdope.com/t/clouds/80355/1 "2001-09-08T04:27:14Z")
And now, deep thoughts… Has anyone ever wondered how far two people can be apart and still see the same cloud? I know there would be a lot of factors involved, but just on average. Say I was looking at a cloud in southern Michigan, could someone see that same cloud from Ohio? Just a thought… ---
**Author:** ![Crunchy\_Frog](https://avatars.discourse-cdn.com/v4/letter/c/ebca7d/32.png) [@Crunchy\_Frog](https://boards.straightdope.com/u/Crunchy_Frog)\ **Post date:** [September 8, 2001, 4:39am UTC](https://boards.straightdope.com/t/clouds/80355/2 "2001-09-08T04:39:50Z")
It’s 11:30 pm central time on a Friday night. Don’t you have some drinking to do, or is that sort of thing that prompted this question? I don’t have an answer, btw. But I’m guessing the Michigan - Ohio thing is a bit far-fetched. Don’t most planes fly above clouds? I’m sure you can’t see a plane from one city to another, but then again a cloud has size on its side. I’m still guessing though, that an individual cloud can only be seen in say, a 30-40 mile radius. ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [September 8, 2001, 5:44am UTC](https://boards.straightdope.com/t/clouds/80355/3 "2001-09-08T05:44:27Z")
The highest cloud-tops listed [here](http://www.atmos.washington.edu/gcg/301/atlas.html) reach 9+ kilometers. So if we just use 9 for convenience and add that to the Earth’s radius (6378 km), a tangent drawn from that point to the Earth’s surface will cover an arc of 3.04° ( cos[sup]-1/sup ). A bit more math yields a land distance of 338.6 km, or 210.4 miles. So theoretically you can see a cloud, just above the horizon, that’s 210 miles away. Of course, atmospheric haze - not to mention trees, buildings, etc. - cuts that distance way down in practice. ---
**Author:** ![Crunchy\_Frog](https://avatars.discourse-cdn.com/v4/letter/c/ebca7d/32.png) [@Crunchy\_Frog](https://boards.straightdope.com/u/Crunchy_Frog)\ **Post date:** [September 8, 2001, 9:35pm UTC](https://boards.straightdope.com/t/clouds/80355/4 "2001-09-08T21:35:05Z")
Hey! I was only about 140.4 miles off! Ever better if I lie and claim I was taking trees, hills, atmospheric haze, etc in question… ---
**Author:** ![Rilchiam](https://avatars.discourse-cdn.com/v4/letter/r/2bfe46/32.png) [@Rilchiam](https://boards.straightdope.com/u/Rilchiam)\ **Post date:** [September 9, 2001, 5:15am UTC](https://boards.straightdope.com/t/clouds/80355/5 "2001-09-09T05:15:45Z")
[Winnie the Pooh]How sweet to be a cloud Floating in the blue! Every little cloud Always sings aloud.[/Winnie the Pooh] ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [September 9, 2001, 6:37pm UTC](https://boards.straightdope.com/t/clouds/80355/6 "2001-09-09T18:37:43Z")
**Crunchy** , I’ll be nice today and cut you some slack. If, to clear land obstructions, we say that a cloud has to be at least 10° above the horizon to be visible, the arc on the Earth reduces to a mere 0.45° (law of sines), which translates to a land distance of 49.9 km, or 31 miles. Now, also notice that these calculations are based on the _highest_ cloud-tops. If we use a height of, say, 10,000 ft., (3 km - completely arbitrary, but seems reasonable), then the “horizon-view” distance is 195.6 km, or 121.5 miles, and the “10°-view” distance is a scant 16.9 km, or 10.5 miles. ---
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [September 10, 2001, 3:31am UTC](https://boards.straightdope.com/t/clouds/80355/7 "2001-09-10T03:31:34Z")
So does this mean these people have looked at clouds from both sides now? ---
**Author:** ![TroubleAgain](https://avatars.discourse-cdn.com/v4/letter/t/e480ec/32.png) [@TroubleAgain](https://boards.straightdope.com/u/TroubleAgain)\ **Post date:** [September 10, 2001, 11:38am UTC](https://boards.straightdope.com/t/clouds/80355/8 "2001-09-10T11:38:50Z")
::Slaps Zebra upside the head:: [sarcasm]Thanks for bringing up that song![/sarcasm] 😃