UKC

... To blow clouds of spray from the surface of the water?

Was camping at loch einich in September, and it was windy- a southerly was blowing off the plateau and would drop down the 1500ft or so onto the loch. Every minute or two a particularly strong gust would lift a curtain of spray a good 50-100 ft in the air, which would then be blown the full length of the loch and on down the valley. We had to find a hollow 100m or so back down the track to get a bit of shelter, but it was still the windiest night I've every spent camping.

Next day, climbed braeriach, via coire an lochain, and the same thing was happening- you could see the gust of wind slam into the surface of the loch (loch coire an lochain- a rather circular name!) and lift huge curtains of spray; walking past the outflow we had to crouch down when the gusts hit before making progress between them

What sort of wind speed is needed to produce that effect?

Funnily enough, the actual summit of braeriach was completely calm, as the wind was deflected above it by the cliffs to the south...

Cheers
Gregor

In reply to no_more_scotch_eggs:

Sounds to me like you're talking about force 8, maybe 9. (Which would be somewhere in the region of 38 - 55mph.)

Here y'go, have a look at this: https://en.wikipedia.org/wiki/Beaufort_scale#Modern_scale

In reply to no_more_scotch_eggs:

8 on the Bleaufort Scale. 38 mph .

In reply to Dave the Rave and deepsoup:

Thanks for speedy replies- and for link, deepsoup- should have known Wikipedia would have the answer!

I think it was probably 7 at loch einich then, maybe 8 at coire an lochain- though notably gusty at both sites, mean speed probably a good bit lower.

Was a memorable trip, and a fantastic mountain..!

Cheers
Gregor

In reply to no_more_scotch_eggs:

Aye continuing the nautical theme the topography probably mimicking the punchiness of a Katabatic wind flowing downhill, maybe around 50mph. Back in ma seafaring days I remember on a few occasions, calm seas approaching a Glacier then mental winds with the ship heeled right over as violent winds funneled down of the ice causing the air to be filled with blowing spindrift. Ten minutes later nice and calm. Sounds like a memorable and very enjoyable camping experience

In reply to Joak:
It was- the Cairngorms are just such a fantastic environment. Love visiting them. Will get to an Garbh coire on beinn a'bhuird and do squareface one day soon...

Your sailing trips sound fantastic- where were you? Agree re the katabatic comment- reminded me a bit of trekking in Torres del Paine, though that was even more extreme- sudden bursts of wind from otherwise calm air. The Cairngorms trip was more sustained (though we had uncommonly good weather in TdP...)

Cheers
Gregor

Edit- just looked at your profile and seen squareface is in your favourite climbs... The photos in classic rock make it look just stunning. Have to get there soon...

In reply to no_more_scotch_eggs:

The katabatic winds were in South Georgia (during winter) in the Southern Atlantic. As well as the conflict I did a couple of other trips doon there, nae doubt punishment for some wee drink related blips in otherwise exemplary behaviour! Awra best wi Squareface next year, a fantastic day oot

In reply to Joak:

South Georgia- would love to get there. Were you there in 82? Ive read about it, but it must have been a hell of an experience...

i Did get out to the Falkland Islands about 15 years ago, but that was easy- scheduled flights from punta arenas. Loved it- fantastic place. But South Georgia a lot harder to get to- guess i'll do one of the cruises at some point

Squareface might be year or two yet- would be daft not to do the cummington-crofton when I was there, and need to get out more again for that after a few years of low mileage- more likely the year after, but will definitely get there....

Cheers
Gregor

In reply to no_more_scotch_eggs:

Aye doon there in 82, 84 and 85, a young rebellious twenty something. Visiting Shackleton's grave was very special. Meeting a boss who had previously sacked me who flew down to join the ship I was now on a little less so. To his credit he buried the hatchet, I ate humble pie and the remaining six months could almost be described as "bearable"

In reply to no_more_scotch_eggs:

Would the answer my friend, be blowin' in the wind?

In reply to Morgan Woods:


Looks like over 5 you get some spray .
And would it depend if it was very salty, and or very pure fresh water?
Would it depend on the attack angle of the wind, or if it is swirling ?

I don't think it is an exact science.

Sounds like vertical gusts, in which case the descriptions of Beaufort scale wouldn't apply. Not too many vertical gusts on the open sea.

In 30 years of sailing I've just once been out in a steady force 9 (50mph) and the bottom couple of metres of air were full of spray, like a layer of fog. I haven't seen that any other time and now forecasting is better, I probably won't see it again.

In reply to Dogwatch:

Yes- definitely vertical gusts- very clearly so at loch coire nan lochain, you could see them striking the water and radiating out in all directions, though predominently away from the cliffs. Localised, intermittent, though frequent (every minute or so), and obviously much greater velocity than the mean speed.

But, Definitely not what you describe re being out in a force 9- sounds terrifying...

Anyone with a background in mountain meteorology able to speculate on what sort of wind speeds can be generated on UK hills in vertical gusts like that?

Best wishes

Gregor

In reply to no_more_scotch_eggs:

Would be nice to see what reply you get: several years back I was lifted briefly off my feet on Glamaig and the wind was sending high curtains of spray down Loch Sligachan at the time (moving south-west towards the land)

In reply to no_more_scotch_eggs:

"But, Definitely not what you describe re being out in a force 9- sounds terrifying.."

Part of a race in the Solent with around 20 knots forecast. We didn't even rig the 2nd reef. At one point a team on a light-weight day racer (J24) planed past up at twice the speed with full spinnaker up, whooping and hollering in delight. Later we heard a J24 was knocked down and one crew drowned. I've never been quite sure if it was the same guys.

It wouldn't happen now, forecasting is better and race organisers more risk-averse.