1. “Mammatus clouds over northeast South Dakota, . US. Mammatus, also known as mammatocumulus (meaning mammary cloud or breast cloud), is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. They can produce some dramatic and unusual patterns on the sky and are also associated with severe storms.”
2. “Noctilucent clouds are crystals of ice hanging around 80 kilometres high in the atmosphere that catch the light of the sun long after it has set on the horizon. Natural nacreous clouds occur at altitudes of 20-25 kilometres. The cloud in this image was formed from the exhaust of a missile launched from a distant firing range.”
3. “Flying saucer or Lenticular cloud”
4. “Von Karman cloud vortices above Alexander Selkirk Island, Chile. These clouds look like they have had a hole punched through them. In fact they are naturally occurring vortices crafted by wind patterns on the clouds. In this image these cloud vortices (swirls down left) have been caused by the peak of Alexander Selkirk Island (bottom left) disrupting wind-blown clouds.”
Can’t get enough of this stuff.