Who knows about wind then?

   This is windy Weymouth this morning. You can see the wind gradually building through the morning then a big spike at 79.4kts(!!) followed by a sudden drop and a swing in direction. What causes the spike?

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ellistine Send Private Message Find Member's Posts Really should get out more Joined: 06 Mar 08 Online Status: Offline Posts: 762	Post Options Post Reply Quote ellistine Report Post Quote Reply Topic: Who knows about wind then? Posted: 03 Jan 12 at 2:06pm
	This is windy Weymouth this morning. You can see the wind gradually building through the morning then a big spike at 79.4kts(!!) followed by a sudden drop and a swing in direction. What causes the spike?

JohnW Send Private Message Find Member's Posts Really should get out more Joined: 17 Jul 07 Location: United Kingdom Online Status: Offline Posts: 552	Post Options Post Reply Quote JohnW Report Post Quote Reply Posted: 03 Jan 12 at 2:28pm
	The spike coincides with the cold front passing over. In front of the front (blue) the isobars are close together (high wind), as the front passed the wind veers more to the West and the isobars are more spread out (lower wind). Edited by JohnW - 03 Jan 12 at 2:32pm

ellistine Send Private Message Find Member's Posts Really should get out more Joined: 06 Mar 08 Online Status: Offline Posts: 762	Post Options Post Reply Quote ellistine Report Post Quote Reply Posted: 03 Jan 12 at 2:39pm
	Mmm. Picture paints a thousand words and all that. To be honest I didn't appreciate the wind blew parallel to the isobars. Presumably the spike is equivalent of a bow wave?

bferry Send Private Message Find Member's Posts Posting king Joined: 01 Jun 09 Location: Malta Online Status: Offline Posts: 190	Post Options Post Reply Quote bferry Report Post Quote Reply Posted: 03 Jan 12 at 2:49pm
	On a low pressure isobar, the wind runs anticlockwise along the isobars rather than parallel.
	Bernard Vareo 249 Miracle 2818 Malta

G.R.F. Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 10 Aug 08 Location: United Kingdom Online Status: Offline Posts: 4028	Post Options Post Reply Quote G.R.F. Report Post Quote Reply Posted: 03 Jan 12 at 3:04pm
	Really strong gusts are generally colder heavier air coming down from higher up and lots of things can concentrate them, like a load of water suddenly coming down behind or to the side of them, just as it can have the opposite effect (rain). It was sheeting down here just before the wind dropped and veered (did it veer never can remember if its veering or backing when it goes round to the North West as it generally does after rain or a front going through. I worked out why it did it once whilst watching a particularly heavy and localised squall and wondered if it did the opposite in the Southern Hemisphere.. Edited by G.R.F. - 03 Jan 12 at 3:04pm
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alstorer Send Private Message Find Member's Posts Really should get out more Joined: 02 Aug 07 Location: Cambridge Online Status: Offline Posts: 2899	Post Options Post Reply Quote alstorer Report Post Quote Reply Posted: 03 Jan 12 at 8:28pm
	in central Scotland, we had a massive spike at around half-six this morning- proper house shaking stuff- followed by hours of "bloody hell"- something like 97mph in Glasgow, 105mph in Edinburgh. I was supposed to be taking a train back to the uncivilised south, but instead I'm still a sensible distance north. For some reason i'm drinking Kentish beer mindyou.
	-_ Al