Everybody knows that there are winds aloft that cause clouds to move across the sky as we view them. Usually the clouds appear to change shape as they move and they change their positional relationship as they move.
This afternoon as my wife was going to work I was outside checking the sky out and I stood for several minutes as these clouds moved rapidly across my field of view. It finally dawned on me that not only were they moving rather quickly (not unusual), but they were maintaining their position relative to each other as they did it.
The it dawned on me that I should probably shoot this! (sometimes I'm a little slow on the uptake)
This first shot was taken almost directly overhead. All three shots with the 5N/CV15 wide open.
This one taken 1 minute later was at about a 45° angle between vertical and horizontal.
And this one taken a minute after the second one.
I just thought it was strange that they would move that far, that fast, and still be in much the same position relative to each other.