>>I'm standing outside. I would have to guess at the height of the clouds, but is there a basic calculation to tell me how far away, by land, that cloud is? Is it simply a2 + b2 = c2? Not counting for the curvature of the earth? I think kind of yes, but since I'm only guessing at the height of the cloud (a2), and I don't know the distance on land from where I'm standing to directly underneath the cloud (b2) and I sure don't know the distance I am fro the cloud directly (c2) then I must have to use angles. This all came about because a little girl asked me how far away a cloud was. What was it over?
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>You might be able to work it our (v roughly) from the cloud type. different clouds typically form at different altitudes that might give you a rough height

I was thinking along those lines too: http://136067.brightwebsite.com/cloud-types/