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Dust devil on the Old Man of Coniston  

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Old Man of Coniston
A lone glider soars over the Old Man

Author
Geoff Moss

Pilot profile
Intermediate. 

08 Jun 2013
Original post on the CSC forum 

27 Dec 2015
Added to Knowledge Base

Related articles
Dust Devils by Adrian Thomas (Expert pilot)
Dust Devil on Wikipedia
What are dust devils? at WeatherQuestions.com

 

Tim Oliver and myself walked to the top of Coniston Old Man today. We met Simon Blake at the top who had just walked back up after a short flight half way down the hill.

We sat around for a while, a little disappointed that there was no sign of the light easterlies suggested by some of the forecasts. There was no wind at all. Occasionally a very light flow would appear for a minute then disappear again. Rarely was the flow directly up the slope. Simon had already gone down once and it didn't look promising. The large over-developed clouds around cast shadow over all the nearby land. Only the Helvellyn ridge in the distance appeared to be catching any sun.

I had the school run to do, so I was keen to get off and down to the car park. My glider was laid out and I was stuffing the harness with glider bag etc. Another stronger flow arrived....down the slope. It curled my glider over and threatened to blow it downhill. I walked round and grabbed the LE to stop it rolling down the slope.

The down slope flow persisted. Simon ran 30 metres up the slope and stood, arms outstretched, facing east into what was obviously a pretty strong breeze. Simon's T-shirt flapped vigorously in the wind and to my surprise he declared that it might even be blown-out. "Well, that came from nowhere" I thought.

Blown out! 10 mins earlier there had been no wind at all. As I pondered this curiously speedy change in conditions I realised I could hear the wind whistling over the summit ridge. It really was amazingly windy. I could hear a nearby group of walkers exclaiming "where did that come from"? As I listened I noticed that a bit of polythene sticking out of one of the walkers packs was vibrating furiously in the wind. It was as if the bag was being held out of a car window, doing some speed down a motorway. I realised I could even hear the wind roaring a little, the walkers voices grew quite excited. The wind really was blowing hard.


Dust devil throws hang glider - On Vimeo


The penny was slowly dropping and I watched the walkers with renewed interest. As I stared up the slope a small tuft of grass lifted vertically and quickly into the air. It described a spiral as it shot upwards. I looked up the slope towards Simon and the walkers and quickly described a twisting motion with my hand, to signal what I thought was going on.

My attention turned to my glider laid out on the slope. The whirling wind was only about 25 metres up the slope. What might happen to my glider if the roaring twisting wind caught it, didn't bear thinking about. Now, when I say my glider, it wasn't mine but a brand new demo wing for me to try out. How would I explain this.... I quickly went to a wing tip, grabbed two firm fistfuls of nylon and pressed my hands hard onto the ground.

A few seconds later the leading edge twitched, then suddenly the full length of the glider shot into the air. It streamed skywards, twisting and flailing madly. Then I noticed my harness was airborne and flying round above me too.

I worried that I might get caught up in the glider and be hoisted aloft with it. I got ready to move if I had to.

The wind roared around my ears and as I stared up at the now vertical glider I realised it wasn't the only thing spinning round up there. My flying suit, fleece, glove, sun hat and even my helmet were all airborne. They were all whirling around in the vortex and being carried away down the slope. I hung on to the glider and saw Tim and Simon bounding down the slope after my gear which bit by bit dropped out of the mini-twister.

It took about 20 or 30 secs for the twisting wind to move off and as it did so the glider returned to earth. It looked a twisted mess of fabric and line. I was now particularly keen to get it packed away quickly! I would definitely be walking back down. Tim and Simon helped pack the glider which actually wasn't too badly tangled. A later careful inspection of the glider, in the calm of my back garden, revealed it to be in perfect health. Phew.

I'm very glad I was not clipped in when the dust devil reached the glider. It was surprisingly powerful and I've no doubt that I could have been catapulted into the air. If you've not seen it before then check out this video of pilots being shot aloft by a dust devil.


Dust devil lifts two pilots - On YouTube


The Coniston dust devil was very difficult to spot as there was no airborne debris in it. I was lucky to see a small tuft of grass go into it. If you were to fly through something like it low down it could be disastrous. You would never have spotted it from the air.

Conditions today at Coniston Old Man. 
No wind. Big, tall, bubbly clouds covered most of the sky, blotting out nearly all sunlight near Coniston. The sky looked very unstable and weather forecasts had suggested that the odd thunder cloud might form later in the afternoon. The cloud cover was extensive so consequently there was no significant heating of the ground during the incident or for a while before (dust devil formation is usually associated with strong surface heating). RASP showed a modest 'Thermal Updraft Velocity' of approx 250ft/min for the Coniston area.

Food for thought....Geoff Moss

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