Jaw dropping Tsunami Cloud rolls over Sydney

Last week a cloud formation that look like some kind of “Tsunami Cloud” rolled over Sydney and made their citizen dropping their jaws. Technically this is a massive shelf cloud that is stretching several kilometers across the sky..

“[The shelf cloud] is created by a cold outflow from a thunderstorm lifting the moist air very abruptly, it is an outflow feature from a thunderstorm. “When the rain from the thunderstorm comes vertically down it drags the air with it, it spreads horizontally and forms a gust front, you get the humid air being lifted abruptly from the outflow of the thunderstorm.” - The Daily Telegraph