clouds

Here’s an interesting email: Terri O’Hanlon wrote in to say, “Clouds don’t “move over the area.”  It’s actually the earth rotating under them. Just sayin’.”

Well, without going into all the complexities of relativistic theory, I’m afraid I’m going to have to disagree with Terri. If it were just a matter of the earth moving underneath the clouds then you would have to assume that the clouds were “stationary.” And the clouds would then have to be stationary with respect to some point of view…say the center of the galaxy.

earth_rotate_sm

Here’s the problem… If those clouds are stationary in the earth was just spinning underneath them, the clouds would be moving by us at over 700 mph. Because that’s the approximate speed that we are spinning at our latitude. But of course the clouds are not moving by us at that speed. Instead you can assume the earth and the atmosphere are moving as a single unit in its orbit around the sun. So any reference to the clouds moving above us is made using us as the stationary point of reference which is certainly appropriate to do. So indeed the clouds are moving… And they are moving over us. Otherwise without a point of reference, it all becomes nonsensical.

 

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