Lenticular clouds over Mount Otensho, Japan. (Wikimedia Commons)
Photo of a brocken spectre taken by a passenger in a Boeing 747 airplane. A brocken spectre is a phenomenon by which the observer’s shadow is surrounded by rainbow fringes. (M. Royon)
Mammatus clouds over Regina, Saskatchewan, Canada. (Wikimedia Commons)
An aerial view of morning glory clouds near Burketown, Australia. (Mick Petroff)
Lenticular clouds over Mount Jefferson in Oregon. (Wikimedia Commons)
Lead image of asperatus clouds over New Zealand by Witta Priester. To see more of her work, visit her Flickr page.