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Wild Wassa
10-27-2002, 09:41 AM
I was on Canberra's Lake Burley Griffin, this arvo, a lake notorious for flukey winds.

The fleet was becalmed, except for me. I don't like dirty air, I'm always apart from the fleet.

A strip of wind the width of a roadway, 6 or 7 metres wide, came running down the lake, in a perfect orientation to one of the marks, lasted for minutes, it seemed as though one of the gods had sent it. The water was almost glassy on either side of this strip of wind.

Does a wind like this have a name? I have not ever seen such a phenomenon.

I wish I could have photographed the water's surface.

Warren.

ps, This one good leg, was worth today's torment. Damn all Laser 4000's. I would be banned if I told you what I thought about Laser 5000.

[ 10-27-2002, 09:57 AM: Message edited by: Wild Wassa ]

Gary Bergman
10-27-2002, 10:18 AM
Zephyr?

Wiley Baggins
10-27-2002, 10:28 AM
I have had that happen to me as well. I don't know what to call it, but that is one of the joys or curses of sailboat racing (or sailing in company with other boats...impromptu racing)

The other neat thing is when you are trailing (I mean when a friend is telling you about the time they were trailing ;) ) and the wind line starts behind you and you ride it to the lead boat(s).

Mr. Know It All
10-27-2002, 10:38 AM
I'll bet the answer is somewhere on this site------> http://www.windpower.org/tour/index.htm
Tunnel Effect?
Kevin in Ohio

[ 10-27-2002, 10:48 AM: Message edited by: Mr. Know It All ]

Wild Wassa
10-27-2002, 11:13 AM
Billy B, the ride was worth about 600-800 meters of catchup to 18ft cats (mixed handicap A, B, V and Cats). It wasn't a shute comming from a gap between trees which I could have expected, it ran straight down the centre of the lake. I'm glad that you have experienced a similar situation. Obviously it was something that you remembered. I think my son and I will.

Gary, it was a Zephyr as though squeezed from a tube. 'But' without a funnel?

Mr Know It All, that's why you are called Mr Know it All, thankyou Sir. I'll get into some wind science.

Warren.

B. Burnside
10-27-2002, 12:12 PM
Warren, were there clouds? What were they doing? Sometimes you get a little patch of wind under the leading edge of a cumulus cloud, but you would have been seeing those little puffs come and go all day. Maybe that's what you meant by flukey?

Mr. Know It All
10-27-2002, 12:17 PM
Warren......My nickname was given to me for just the opposite reason. I don't know sh@t and have to look everything up, but my research skills are improving. :D
Kevin in Ohio

Meerkat
10-27-2002, 02:03 PM
Sounds like a micro-burst, thus the questions about clouds nearby.

Gary Bergman
10-27-2002, 03:26 PM
I thought you were looking for a sailing term, not a meteorological one. Excuse me. Fair Winds, back to sailing

Wild Wassa
10-27-2002, 04:58 PM
Barbara, On the previous day, Saturday afternoon, they were the highest clouds that I can recall in Canberra. Canberra is in a valley, 19k's from the northern end of the Australian Alps, and is surrounded by mountains. Lake Burley G is 680 mts ASL. Maximum temp yesterday was 20 oC (68 oF), perfect. The cloud formations here are not normally spectacular.

The Cirrus, Cirro Cumulus and Cirro Stratus remained until mid morning yesterday, Sunday. Then they changed to 'small' Cumulus. The Cumulus were on every horizon. Above Canberra was zero cloud cover, after lunch.

Today, Monday morning there is zero cloud cover to all horizons. The quiet preceding the storm?

Kevin, :D , did you just describe me?

Meerkat, Hi Dave, I took your advice. When we bailed yesterday, every drop was thrown over the stern, with force. I beat my Boss, Gary L, by two boatlengths, I put it down to your good advice. We only bailed when we were becalmed, :rolleyes: . Gary wasn't talking to me after the first race. He flogged me in the second race. Now I'm not talking to him, ;) .

A microburst, this is what it would be, this was not a parcel of air in opposition, :D , it certainly was hard edged though. It looked like a road tarmac on the water. The first time that I haven't had to ask for directions to the mark.

Gary B, I welcome your answer. Now every bit of good luck I'll putdown to a zephyr.

Warren.

ps, Some microbursts, are called bullets and are in opposition.

[ 10-27-2002, 05:58 PM: Message edited by: Wild Wassa ]

Ian McColgin
10-28-2002, 09:53 AM
The one time that happened to me it lasted longer. It was the return leg from Block Island down Long Island Sound and the entire fleet was becalmed - anchored against the ebb tide - we way in the rear when our spinaker filled. As we sailed over the anchor I pulled it up and we carried on for 20 miles past boats that either didn't grab it or didn't get it at all.

The cat's paw on the water was about 100 square meters. Usually these things move across the water at the wind speed - in this case perhaps 8 knots - but this private puff was either being renewed or coming from a slow moving down draft or something because we sailed in it happile at about 3 knots for some hours - went right through the whole Off Soundings fleet.

Anyway, as hinted above, the visual image of the bit of wind marked water dappeling an otherwise glassy sea is called "cat's paws" 'cause that's what they look like creeping across the surface.

If you have it to yourself, it's a "private puff."

bud
10-28-2002, 11:53 AM
Interesting when you watch a burst of wind coming at you across the water, & when it hits you realize the wind direction within it is not the same as the direction the burst is travelling across the water.
Did that make sense?
I stood this summer on my porch watching as a ferocious thunderstorm hit, I could actually see the trees pushed apart as if a "bomb" of air came straight down.

B. Burnside
10-28-2002, 04:27 PM
There is an informative but poorly organized and difficult (IMHO) book by Alan Watts about "Dinghy and Board Sailing Weather". If I understand correctly there are two things operating in the situation Bud describes.

One is that wind at cloud level is indeed going a different direction from wind on the surface. I'm not sure of the mechanics, but I think it's that surface wind direction is modified by drag from the earth's surface, while upper air isn't.

The other factor is that if you looked at thunderstorm cells in cross section, the wind in front is moving down, because it has cooled enough to make the squall happen, and surface wind at the trailing edge of the cell has warmed up again and will be going up.

If you could find a friendly little cloud and hang under it, you could really go places.

Barbara

TomRobb
10-29-2002, 01:16 PM
On our inland lakes where we suffer nobly from lack of proper wind we look for Cat's Paws smile.gif

Wild Wassa
10-31-2002, 02:34 PM
Where has my long posting gone? Oh no!

Windows XP I bet, I'll be back.

Warren.

[ 11-01-2002, 04:14 AM: Message edited by: Wild Wassa ]

Adam C
10-31-2002, 02:39 PM
I think it's called Breaking Wind
:D

Wild Wassa
10-31-2002, 02:46 PM
Certainly venting.

Meerkat
10-31-2002, 02:51 PM
Wassa: I'm glad my advice brought you victory. However, if you where discharging that water from the spigot directly, that sight alone might have distracted your competition ;) A protest about illegal jet propullsion? ;)

Wild Wassa
10-31-2002, 04:49 PM
Meerkat, Hi Dave, The win against my Boss was shallow. I had to endure the embarrasment of being in fibre glass for 2 hours 40 minutes, this was character building, though.

Thanks again Meerkat, I wonder what trick I can pull on Gary on Sunday.

Warren.

[ 11-01-2002, 01:36 PM: Message edited by: Wild Wassa ]

Wild Wassa
11-01-2002, 04:31 AM
Thankyou for the excellent replies, Skippers.

Well the cat was having a big stretch. A terrific term, a cat's paw. Very dangerous for mice.

http://www.imagestation.com/picture/sraid37/p101ebf09afd92826aac3f1f6899d61c6/fd18d4ce.jpg

The Fireball. Best for the young ones to feel confident while the boat's stable. Taken looking through the sunnys.

Warren.

ps, Alternative title, Hanging out.

[ 11-01-2002, 01:26 PM: Message edited by: Wild Wassa ]