Is this weird?

Try and imagine this...

I'm looking out of the office window to a very colourful sky - there are at least 6 windows so I have a pretty wide view. The view is split into 3 - sky on the left, a high rise building in the middle, and then more sky on the right. The view is of New Jersey, across the Hudson river.

Why is it that the clouds on the left are moving quite fast and that the clouds on the right are stationary?

Do you think that's weird? I do. I've been looking at it for ages, and it's still doing it. If I had a camera I'd take a picture, but I don't.