Australian Weather Calendar: July 2017
Rob Embury was visiting Lord Howe Island, 600 km off the coast of New South Wales, when locals alerted him to this cloud over the island's two distinctive peaks.
Lenticular clouds are near-stationary, lens-shaped clouds that usually form on or downwind of mountains or elevated areas. When moist air is forced to rise over an obstruction, water in the air condenses, forming cloud. As the air descends down the other side, the water evaporates again, resulting in the distinctive lens-shaped cloud seen in Rob's photo. The layered effect is caused by several parallel airstreams, alternating moist air and dry air, at different heights.