Australian Weather Calendar: April 2017

April photograph by Pamela Pauline

Pamela Pauline caught the sky over Mona Vale, New South Wales, in transition.

The lumpy cloud on the left of her photo is asperitas cloud, formed in turbulent air. Asperitas is a newly-named cloud formation–the first to be added to the World Meteorological Organization's Cloud Atlas in over 50 years. On the right is the gust front and precipitation associated with an approaching thunderstorm. The ragged cloud in the middle is cumulus fractus, indicating the leading edge of the gust front as it moves from right to left. This storm developed in the instability caused by a broad region of low pressure across eastern Australia in early December 2015.