Rolling clouds hit Durban

[darksai]

Looks like these "rare" clouds are spreading right across the globe..

Durban folk had their heads turned skywards yesterday to witness the rare Morning Glory clouds that streaked across the city.
This unusual cloud formation is not clearly understood because it occurs so infrequently, and there are many different hypothesises as to how they occur.
Mduduzi Mthembu, of the Durban weather office, described them as “rolling clouds” and said that this phenomenon occurred before a cold front, and especially in summer.
“When cold, denser air enters a warm environment at a high speed, the warm air lifts and forms clouds in this manner,” [or, or more likely, it has something to do with increased atmospheric conductivity (see comment below on humidity) and the clouds are merely conforming to an electromagnetic structure] said Mthembu.
He added that, even though there was a cold front moving in, there was no need to unpack the winter woollies.
“We are in summer now. There may be some light drizzle tomorrow, but it is clear for the rest of the week.

INLSA
Heavy rain pelts down outside Durbans city hall yesterday. A rare Morning Glory cloud, right, appeared to be caused by the sudden wind and humidity. The meteorological phenomenon is seen most often in northern Australia. There, the Aborigines have noted that they come when humidity is high [more evidence of water being dumped in from comets?] and a strong sea breeze has blown the day before. Some of these clouds can be 1 000km wide and move at 60km/h. PICTURE: Jacques Naude

The rare rolling cloud over Durbans harbour yesterday, which had many Durban people taking to social media networks like Twitter to share their impressions of the freakish summer weather.
Supplied
“We will see reactions like this because the air is so much warmer than it was a month ago when similar cold fronts came in.” [if this is the case, they fail to mention that this would then be a sign that temperatures must clearly be changing faster between seasons, else these clouds couldn't have been rare in the first place]

The thunderstorm that occurred yesterday afternoon was a “typical summer thunderstorm” that had moved from the interior during the day to the coast in the afternoon, said Mthembu.
The Morning Glory cloud is sometimes seen in central America, over the English Channel, in Germany, Russia, Australia and Brazil.
Many people in Durban took to social media network Twitter to share their impressions of the occurrence, so much so that #rollcloud was quickly trending in South Africa.
@GlenPike1 tweeted: “This is how the clouds roll in #durban before the storm.”
@shEeeeevvvVvvy tweeted: “Crazy wind in Durban 2day; and freaky looking clouds too!!!” and @MsJetSetterTaya thought they were “Strange but beautiful”.

Source: _http://www.iol.co.za/news/south-africa/kwazulu-natal/rare-cloud-behind-durban-s-unusual-weather-1.1610559#.Uo7nBeKzLkM

edit: typo

 

[Chad]

Rare 800km long morning glory cloud rolls over Queensland, Australia
By Strange Sounds -
Jul 27, 2016

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A rare 800km long Morning Glory Cloud has rolled across outback Queensland stunning local residents on July 23, 2016.

From Athol station at Blackall by Michael Buttler

The morning glory cloud is a rare meteorological phenomenon often seen in the Gulf of Carpentaria in September but almost never sighted over inland areas.

From Athol station at Blackall by Michael Buttler

This roll cloud has been observed in Ilfracombe, Longreach, Blackall and Tambo. However satellite imagery suggests that it extends even further to around Dalby. This is an incredible 800km in length and about 2-10km in width.

via HigginsStormChasing

The huge cloud, coming out of nowhere, formed into a roll and suddenly into something looking like a huge wave over Blackall.

From Ilfracombe via Mark Tysoe

Another witness from Ilfracombe, nearly 200 kilometres away, also saw the gigantic cloud in the distance.

From Ilfracombe by Ashleigh Bielenberg

Meteorologists explain that roll clouds are generally only seen in the Gulf of Carpentaria, where their formation can be predicted and observed on a more or less regular basis due to the configuration of land and sea in the area.

By Debbie Searles via Twitter
So why did it form in dry central Queensland?

Inland they’d be associated with a change of air mass, a wave coming through as it were, and in this case a gravity wave.

From Blackall by Sam Carter

Something that is a little bit heavier than the surrounding air pushing into south-west Queensland from the south-east.

From the distance near near Ilfracombe by David Taylor

In other words, the unusual cloud formation was associated with a cold front moving through, and meeting the warm air ahead of it.

Under the cloud at Ilfracombe via David Taylor

If there’s enough moisture in the turbulence that’s caused by this wave coming through then it will generate a line of cloud.

In this particular instance it was a beautiful and well defined morning glory. But I wouldn’t expect to see another one any time soon.



Morning Glory Cloud Formation

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Sott related article: Australia: Mysterious Tubular Clouds Defy Explanation