Rise early for ‘morning glory’
October 04 2014 10:59 PM
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By Steff Gaulter

There was a bit of excitement in Qatar last weekend, when it rained. Unfortunately, the rain didn’t quite stretch to Doha, but photos from other parts of Qatar showed quite a considerable amount of wet weather. At one point, the satellite picture showed an impressive area of cloud over central Qatar that did threaten to bring rain to Doha, but alas it was not to be.

The last time it rained in Doha was 14th May, so it’s certainly an event when there is a shower. It would have been a little earlier than usual after the summer for rain to fall, but it wouldn’t be unprecedented; just two years ago a huge thunderstorm rumbled over Doha on 28th September.

Doha isn’t the only place in the world where the sight of clouds brings a wave of excitement on social media. At this time of the year, there’s a similarly rare phenomenon that affects northeast Australia. This isn’t a location like Qatar where the sight of any cloud is rare, but this is a very unusual type of cloud that attracts people from thousands of miles away.

So special are these clouds over northeast Australia that there is now a festival in its honour, with live music, rodeo events and ranger tours. It’s celebrated in September every year in the tiny town of Burketown, which is located on the Gulf of Carpentaria in far northwest Queensland. The town is tiny, in the 2006 census it boasted a population of just 173, but in September and October every year, this number rises dramatically as the mysterious clouds roll in.

This cloud has the rather dubious name of morning glory, and it’s a roll that stretches from horizon to horizon. It hangs low in the sky, reaches one or two kilometres (up to 1.2 miles) high, and only about 100 or 200 metres (325 to 650 feet) above the ground.

The cloud rolls westwards over the tiny town first thing in the morning, usually at speeds of around 60kph (37mph). Sometimes it’s just one roll of cloud, other times it’s two or three. In fact, on rare occasions up to eight have been seen, following each other in quick succession across the sky.

Added to the mystery is the fact that the cloud isn’t seen every day, and is only seen for a few weeks every year. No meteorologist can guarantee that the morning glory cloud will form, but they can say there’s a greater chance on some days than others. This means that anyone who wants to see the cloud has to get up at the crack of dawn and simply wait to see whether nature delivers.

The cloud isn’t just a breathtaking sight, it’s also got particular properties because it’s rolling. This means that the people who pile into the tiny town aren’t simply cloud-spotters and meteorologists, but gliders and pilots.

The rotating nature of the cloud means that at the front of the roll is air which is rising up over the advancing cloud.

If pilots stay just ahead of the cloud, then they can continue to soar for many miles, in fact, some have claimed to have travelled as far as 900 kilometres (560 miles). The uplift offers pilots a similar effect to that which surfers get in the sea, allowing pilots to swoop and spin in front of the rolling cloud.

However, pilots are also aware that there is an equally powerful downdraft behind the cloud. This could easily hurl a glider directly towards the ground, crashing into the crocodile-infested landscape.

Queensland isn’t the only place in the world where a roll cloud has been seen, but it is the only place where a morning glory cloud occurs with some degree of regularity. It doesn’t happen every day, but, thanks to the climate and the geography of the region, it does occur fairly regularly in September and October.

The special roll cloud occurs in the months that the north of Queensland is changing between the dry season and the wet season. Winter in the southern hemisphere is between June and August, so this is the coolest time of the year. The Gulf of Carpentaria starts to heat up in September and October, and at this time of year the region swings back and forth between the conditions of the dry season and those of the wet season.

As the region heats up, the land heats up faster than the surrounding seas. The Cape York Peninsula is the northern part of Queensland which juts out 800km (500 miles) into the sea. Sea breezes form around its coasts, which converge in the centre of the peninsula, forcing the air to rise and form clouds and showers.

If the winds are from the northeast, as they often are in September and October, then this line of clouds will be guided westwards towards Burketown, which lies just to the west of the base of the peninsula.

Generally, whilst it’s over the water, this line of clouds will have a ragged appearance, but once the southern end moves over land it can form into single or multiple morning glory clouds. However, the clouds can only form when the upper atmosphere is still in the ‘dry season’ phase. Once this gives way to the wet season conditions, the rolling nature of the clouds are lost and instead they develop into towering thunderstorms.

The images and videos I’ve seen of the morning glory cloud are spectacular, but given its remote location, I am unlikely to ever see it for myself. A few years ago I managed to drag my long-suffering husband tornado chasing in the US, but I’m not sure even I can sell him a holiday to a remote corner of Queensland. Of course it doesn’t help that we failed to see a single tornado on our US trip, but that’s another story!

 

 

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