These unusual clouds are called lenticular clouds because of their lens-like shape and they tend to form at high altitudes, normally aligned at right-angles to the wind direction.
They have often been mistaken for UFOs in the past, due to their odd shape, but they are becoming more common these days. They are indeed another of mother nature’s wonders, truly a sight to behold!
Photo: Alpsdake/Wikimedia Commons
Photo: R3db4r0n/Wikimedia Commons