UKC

Hi All,

struggling with a question on my Winter ML research paper. any help would be greatly recieved.

Q. What are sun balls and what do they indicate?

I've googled to no avail.

In reply to birdman: Small balls of snow that spontaneously roll down a slope, building size as they go. A bad sign of snow instability and a compelling reason to get off the slope. the ball itslef is not going to harm you, but the potentail avalanche they indicate will!

In reply to nickinscottishmountains:

They can build up to a huge size in the Alps (sun is stronger also) and take the whole slope with them.

In reply to birdman: I'd thoroughly recommend a book called "Snowsense". Worth a read.

In reply to Andy Nisbet: Blimey, I didn't know that, thanks.

In reply to birdman:
Picture here.

http://www.flickr.com/photos/gerald-davison/81659956/in/set-1744693

These were actually frozen solid, they had probably formed one or two days before, then the temp dropped overnight and continued very cold into this day so I wasn't concerned about the slope.

You can see the tracks in the pictures, they extended well up the slope. If you look carefully you can see the layering in some of the "balls" as they roll down and gather snow into a shape more like a wheel than a ball.

In reply to Gerald Davison:

cheers gents!

In reply to nickinscottishmountains:

I found out when I told a chap a slope was safe (which it was from windslab - all I knew in the early 80s). Sunballs set off the slope. I jumped off the avalanche and he went 5000ft, including 500ft in mid air. He survived with minor injuries!

In reply to birdman:

All good replies - just googled it myself and it came up first time. maybe your Google fu is not at it's strongest...

In reply to birdman: I've always called them snow snails (cos they look like a snail shell innit), never heard of them being called sun balls so I learnt something today. Definitely a sign, normally in spring but on any warm/sunny day, that it's too late to be on that slope. One of the few obvious sure-fire danger indicators. They normally occur under a feature like a cliff where things can fall onto the snow e.g. a pebble to start them off.

In reply to Andy Nisbet: Bloody hell, glad he was ok! Wherabouts in the Alps was it?

In reply to birdman: http://lmgtfy.com/?q=sun+balls+mountaineering

In reply to george mc:

Yeah evidently my google fu is fooked!!

thanks for all responses.

In reply to nickinscottishmountains:

Descending from the Grand Montets Station to the Dru.

In reply to Andy Nisbet:

This the same as snow rollers / snow doughnuts?

In reply to birdman:

and be careful not to interpret the marks left by the smaller bouncing ones as 'footsteps' and follow them as i did, once.

In reply to birdman:
Hope you're not doing your assessment at The Lodge..... George'll dob you in to your Course Director......

In reply to Andy Nisbet:

That's remarkable, where did it happen? A calculation shows you'll reach around 120 mph (176 feet per second) after falling 500ft in mid air, depending on your body angle in flight, and the whole flight will take 5-6 seconds in total.

Btw I'm not mocking your post, just interested!

In reply to abseil:

I wouldn't take the distances too literally, but it was an awesome survival. The avalanche was huge. The chap ended up in the middle of a huge amount of debris, staggered off a short distance, and then another avalanche (triggered by the first) landed just where he had landed. His story; obviously I was a long way off and all I could do was go back up and shout for help. He was choppered off very soon after. He had no insurance but I think they were so amazed by his survival that they didn't ask for any money. The hospital likewise just checked him over and booted him out. By the time I got down from the telepherique, he was back at his flat still covered in blood. And totally hyper. Next day he couldn't even get out of bed.

In reply to birdman:




You didn't really google it did you?

In reply to murdster:

https://www.google.co.uk/#sclient=psy-ab&hl=en&site=&source=hp&...

no you're right i didn't bother, i thought it'd be much quicker to write a post on UKC and twiddle my thumbs for a few hours until some kind person told me the answer.

(thanks to the people who have provided me with useful info)

In reply to nickinscottishmountains:

Presumably these are different from the little skittering things that you get coming down grade I gullies all the time?

In reply to Ramblin dave: yeah, that is just winter shrapnel!

For a minute there I thought that you were referring to me.

In reply to Ramblin dave: yeah, like these: http://t1.gstatic.com/images?q=tbn:ANd9GcQPokm-5K9xWjKaaWi7dk_uXhQBtjRPelb4...

They can get quite a bit bigger than that though.

In reply to nickinscottishmountains:

The balls could definitely kill you, I've seen them more than 6' tall on one occasion on ben alder, the weight would be immense and they trundle down faster than you could run.

In reply to Calum Nicoll:

Just like this eh? youtube.com/watch?v=YVbnGANyAC8&

In reply to george mc:

Sair yin!

In reply to Andy Nisbet:

It certainly was, and thanks a lot for your reply. He was really lucky that time, wasn't he.

In reply to Andy Nisbet: I remember reading about this in a book years ago - it stuck in my mind because I knew your name from Scotland. Was the unlucky (well, perhaps rather 'very lucky'!) chap American? Could it have been in one of Simpson's books

In reply to TobyA:

No, he wasn't american. I didn't want to put his name here in case he objected. But I think you're right; it was mentioned in a Joe Simpson book.

In reply to birdman: Tim, I believe that is cheating! See you in a few weeks!

In reply to Andy Nisbet: I believed your account entirely as it was written until you claimed they didn't charge him for the chopper.

In reply to Parrys_apprentice:

He had no money. When the helicopter arrived on the glacier, because I had called for it, he refused to get in because he had no insurance, and said he'd find his own way down. Covered in blood and staggering around, they said then that they wouldn't charge him. I guess they'd flown up there anyway. It's true!