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Cloud waterfalls, the beautiful result of sinking air, not that uncommon but rare to see

By Kate Doyle, Sunday June 28, 2020 - 09:33 EST
ABC image
Cloud waterfalls, like this over the cliffs, then waters, of Bass Strait, need just the right conditions. - ABC

When Cameron Bostock made his way up through the clouds to summit Bluff Knoll in southern Western Australia, he was met with a remarkable sight.



"We got to the top and it was just unreal. A massive, endless sea of clouds, and it waterfalled over the mountain face," Mr Bostock said.

"It was pretty special."

The Perth local, normally based in Tokyo but home because of COVID-19, made the pre-dawn trek with a mate earlier this month, later putting the footage up on a video sharing site.

The walk might have been familiar to Mr Bostock, but the sight certainly was not.

"I've climbed Bluff Knoll four or five times before, one of my favourite spots to go, and never anything like that," he said.

"Never anything that spectacular."



Goldilocks conditions

Mr Bostock said clouds usually did more harm than good when summiting mountains, blocking the view.

But this time they definitely worked in his favour, sitting just below eye level.

According to Jessica Lingard, duty forecaster at the Bureau of Meteorology, that is precisely the trick.

The low layer of clouds was sitting just on top of the ranges surrounding the peak.



"Then we just have a really slight wind and that just sort of wafts [the clouds] over the surface of the hill," Ms Lingard said.

"These clouds are cold and they're dense, and so cold, dense air likes to sink.

"When it reaches the edge of the topography it just sort of falls and drifts over the edge of the topography, creating these beautiful waterfall images."

For the weather buffs out there:
yes, we are talking about katabatic winds, or cold drainage winds, flowing down topography; and
the clouds, so beautifully captured by Mr Bostock, are stratocumulus.

Bluff Knoll is not the only place you can see this amazing phenomenon, it happens in hilly regions all over the world.

To get to see it though, there needs to be something to see.

"It's these Goldilocks circumstances where we happen to have the right thickness of cloud — it's not too thick that the whole thing is totally obscured but just thick enough that you can actually see this process in action," Ms Lingard said.



It also relies on the winds not to being too strong.

"If you've got winds that are too strong it's just mixing up the air too much to allow these sorts of clouds to form," she said.

Ms Lingard said the best time to get to see this phenomenon would be first thing in the morning, before that sinking cool air gets heated up by the sun.

Capturing the phenomenon

Conditions aside, you still need to be out there to see it, and out there with a camera to capture it.

But as Mr Bostock has demonstrated, you do not need a professional film crew to make something special these days.

"I haven't been able to afford any fancy equipment. So most of the really good footage that you might've seen was just off my phone. I leaned it up against some rocks and that was it," Mr Bostock said.

That, and his wicked drone.



Getting out there and sharing the world is a passion for Mr Bostock.

"I love hiking and travelling around, and I love to bring my camera and make YouTube videos and share the experiences of other people, " he said.

"It's just especially cool when I get to share these unbelievable moments that you don't see very often."

His advice for anyone else hoping to capture awesome natural phenomenon is "just do it. It doesn't always have to be planned either".

"If you just put yourself in the right circumstance you never know what you might see," he said.


- ABC

© ABC 2020

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