ok an interesting question for you guyz....


what factors influence gustiness?

temperature/air density,
colder air is denser and seems less prone to gusts

and upwind obstacles

oh and downwind obstacles too

and baked bean consumption :roll:

downwind obstacles?

interesting to hear about colder air reasoning....

yet another reason to avoid tropicial places :wink:

We've been having some really warm winds lately, and yeah there has been turbulence, and heat shimmer across the horizon. Maybe thermal bubbles breaking through an inversion messing up the flow. All the famously consistant warm wind spots I've been to (Cabarete/Dominican Rep., Maui, Fuerteventura etc) have had turbulent gusty wind.

We had a weird day last Sunday - HOT, no blowing sand > beach covered in bikinis, light breeze at beach level yet I was fully powered and jumping high on my 10m (Rhino2 which is actually really grunty for the size).

Yesterday I was ripping around with my 6m Rhino4 fully depowered by the end of the day, and the biggest couple of sets... long clean swell lines... were logo to mast high on Dale Muellers rig, (that guy really knows how to do justice to a wave). Thanks Cyclone Heta.

mmmmm cold air is more grunty and less gusty......

how do u guyz think upwind obstructions affect gustiness...

do u think it's just a case of how big something LOOKS or is distance still a factor after the d/h ratio is taken into account...

ie is it d/h or is it d*d/h?

You would think that a mountain would influence gusty conditions however the main wind direction in Cape Town in a SE and it comes strait over the top of Table Mountain...

Kite Beach is never gusty, even in over 30 Knots.

There is about a 5km brake between the mountain and the beach.

I would agree that cold water might improve on the conditions, as Cape Towns water is enough to frees a polar bear, however I was kiting in Perth last year this time and the wind was not gusty.. in warm water.

This might be a debate point but I think you can boost much higher in a place were the water is colder.. The wind seems to have a better lift to it. (not talking about thermals thought).
Thats just what I have found.
( I guess the place to be is Invercargil.. lol).

About a five kilometer fetch required to smooth out wind - obviously this depends on how big the obstacle is. The distance shrinks a bit the smaller the obstacle, but not much.

The geeks

fyi - tauranga, in particular the inner harbour SW direction and "gustiness influences"

Natures energy, in the form of wind comes up over the kaimai ranges and whizzing down the other side into the inner harbour. then after bouncing off the land mass/water up she goes again and once reaching a certain altitude comes back down. so a up and down wave effect is happening from the trip down the kaimai ranges in the first instance. this is evident when we look up b/c there are large gaps in between the cloud cover, so big long cloud, big gap-blue sky, then cloud again and so on. thus the gusts are somewhere in between the two.....

also when the tide changes this dramactially effects the wind (well in these parts) many times we see the less experienced visitors to these parts turn up, then the wind drops and they pack up. only to find that when the tide turns the wind then kicks back in. we notice this phenomonon most at slack tide, the wind normally gets funky. then when the tide starts running again, in or out, it steadies out again, most of the time........

5 cents worth from the coastal dwellers .......

interested to hear that distance is a huge factor.... even more so than height of object.

how tall is table mountain? that's great news for ihumateo rd by the way as the manukau heads are quite tall but far more than 5km away from IR.

pine harbour is very affected by thermals and rising... before the wind fully fills in the conditions can get attrociously gusty.. but once it fills in at about mid arvo the wind there is sweet.

wind strength also affect gustiness there. up to about 25 knots the wind there is good but over 25 it can get gusty.... far more so than shakers in a sw. must be due to the fact that the hills are far enough away not to affect the lighter winds much but come into play more once the winter winds blow.

ok that bit about about downwind obstacles is a bit poxy

I was thinking more of downwind obstacles making the wind lighter

as in front of big high rises in thailand, the locals rule of thumb was 3 times the height of the tower upwind is dodgy fatter buildings were worse

one hotel was tall and wide across the wind, even a long way out it was like a big wall of light wind, quite hard to get through it and out the other side


as for the changing tide thing, here in Dunedin the oldtime windsurfers always said that the ne seabreeze up the long Otago harbour comes in on the tide, i think it has something to do with the cold water coming in from the sea and making the temperature diff between the sea and the land greater thus giving the seabreeze a wee stir along

enough, bye
craig

i've found this too... downwind obstacles do decrease the windspeed without making it gusty... so the next time the westerly is too strong in auckland... try heading to a place like north piha with the sheer cliffs of the waitaks right behind you, you'd be surprised at how much lighter it is here when places like pt chev and Bramley are nukinified...