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Downburst

sarabande

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Joined
6 May 2005
Messages
34,929
Intriguing met stuff.

It sounds like less than 1 second between the rain hitting the sea, and the crash into the mike. That's 300 ish meters away. Close enough.

The mechanism also interests me. Presumably air rising causes rain to condense, and the condensed rain builds up until its mass and gravity overcome the upthrust.

If the column of falling water is about 100m across and the 'depth' of rain is 50mm, the volume of water is around 390 mcube or the same in tonnes.

Eeek !
 
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johnalison

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14 Feb 2007
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30,271
Location
Essex
I can't help wondering what it would be like to be under it in a boat. Presumably the cockpit would instantly fill to the coamings. There would be nothing much left of the sails. The mast might or might not come down. The hull would be driven down somewhat but would bob up again. Anyone in the cockpit would be severely injured and would be lucky to survive. The hatches might be stove in but I don't think the boat would fill.
 

sarabande

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6 May 2005
Messages
34,929
The terminal velocity of a standard raindrop is ~= 10m/s.

Purely on the basis of that video, I estimate the downspeed of the parcel to be about 40m/s. Area of a 30ft boat is 22msq. so v approx 1.1 tonnes of rain arriving in one lump at speed at very nearly 90 mph. Think of a small fast car hitting the boat


Other estimates are available :)
 

ProDave

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5 Sep 2010
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12,686
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Alness / Black Isle Northern Scottish Highlands.

johnalison

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Joined
14 Feb 2007
Messages
30,271
Location
Essex
Yes I AM missing something. your post and the OP shows just plain text.

When i quote your message then "MEDIA=facebook]788482072098846[/MEDIA] " appears but I can't see the video or anything else. Very strange.
Strange. It was OK both on my PC and iPad.
 

zoidberg

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Joined
12 Nov 2016
Messages
4,513
Perhaps the important thing we can take from this, faked or real, is that such violent downburst do happen and that they are significant to us in small boats....
 

Stemar

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Joined
12 Sep 2001
Messages
17,058
Location
Home - Southampton, Boat - Gosport
I know climate change is happening, but I rather think that if that starts happening in the Solent, the danger of being being caught in it in one's boat would be the least of our worries. Item number 1,452 on my "this is why I like living where I do" list
 
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