© David Gray / ReutersA Chinese tourist watches storm clouds moving along the coast towards the city of Sydney, Australia, November 6, 2015.
The Bureau of Meteorology has warned of severe storms across Sydney, the Hunter region, and the South and Central coasts, saying that heavy rainfall and flash flooding may be in store for residents.
However, this shelf cloud, or more precisely known as an "arcus cloud," came as an advance warning.
A massive shelf cloud appears over #Sydney. pic.twitter.com/HZe62ydNsB
— SMH Photography (@photosSMH) November 6, 2015Gaping onlookers took hundreds of photos and videos of the coming storm, dubbing it a "cloud tsunami."
A shelf cloud is usually attached to the base of the parent cloud - usually a thunderstorm - and it is formed when a downward stream of cool air mixes with an upward stream of warm air.
Shelf clouds are not that uncommon in Australia, and one of the photos of the stunning sight - taken in 2008 by Sunshine Coast Airport worker Shane Loweke - features on the Bureau of Meteorology's 2016 calendar.
"Funnily enough it turned out to be nothing. It sort of blew over pretty quick and we got a little bit of rain out of it," Loweke said.
Comment: Other cloud formations observed around the world this week that are not so common include:
- Rare rainbow cloud spotted by tourist in Jamaica
- Weird 'tornado' cloud over Cincinnati has National Weather Service puzzled
- Unusual wave-like clouds filmed over Breckenridge, Colorado
- Meteor smoke trail? Mysterious cloud formation seen floating over Yanqi Basin, China
With increased dust loading of our atmosphere from exploding space rocks and volcanic eruptions in recent times, we can expect to see more strange and unusual cloud formations.