Because lenticular clouds (you may call them altocumulus standing lenticularis if you prefer) form in the lee of mountain ranges, we see them quite commonly. Rarely are they so colorful, usually just "shades" of white.
Find great photos of lenticular clouds here.
More about them at Wikipedia.
An entire fleet, seen at NCAR in Boulder, the National Center for Atmospheric Research, where they pay attention to such phenomena.