Wind Speed and Density Theories

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Postby Sonny » Fri Oct 05, 2007 2:02 pm

I have never seen any one able ride in 12 mph wind at 3rd with any kite. If you are saying when Alameda sensor reads 12(it reads lower than actual wind), then that's a different story. I can have fun at Alamea when it's reading 14 but I was never able ride when 3rd is reading below 16.
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Postby windhorny » Fri Oct 05, 2007 2:49 pm

Sonny, the sensor at alameda is wierd. When its windy, it is usually blowing close to or above the reading. But it seems when it is light, it reads high. Before the sensor was changed they had some bad bearings in the unit and it did read low all the time. But according to Ikitesurf, they have a new unit as of last year that has been totally calibrated and spot on accurate. But it is only accurate where IT is and not neccessarily for the wind WE get. It is also high up and possibly not affected bythe shadows of the north end of the island. This is all asuming typical directions. when it starts reading from the south and from the north things get a little unpredictable. But there have been quite a few days when it has read 12-15 and i can barely keep a kite up.
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Postby adamrod » Fri Oct 05, 2007 3:08 pm

so, let me get this straight.

1. When it's windy, the sensor is accurate.
2. When it's light, the sensor reads high.

so, when the sensor is blowing 15, it's either windy (see option 1), or light (see option 2).

wow. best sensor EVER.

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Postby windhorny » Fri Oct 05, 2007 6:28 pm

Yeah, i knew I would get some crap for that one. But it is not accurate in relationship to what we get where we are. I am sure the sensor itself reads very accurately, but there is some kind of wind sheer or something wierd. But i may not be right about diagnosing what the sensors compensation is. It is very hard to tell. I just know there are days when it says its 15mph and i cant stya out at all. then there are days it says 0-8 and I am overpowered on my 14. And when it says 30-you know its probably blowing 35-40 1000' from shore.
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Postby ramsey » Fri Oct 12, 2007 2:12 pm

What's an 8 knot day?
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Postby CdoG » Fri Oct 12, 2007 2:45 pm

like we get in alameda all the time
when your not here.
(you show up on 20 Knot days)
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Postby timwim1 » Fri Oct 12, 2007 5:51 pm

So is the bottomline that the wind is more powerful when the air is colder versus when it is warmer, like on a hot summer day? Assuming the same wind reading...

Don't know if I experienced that...

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Postby adamrod » Fri Oct 12, 2007 10:29 pm

i actually think it might be the opposite. it'd be an interesting thought experiment. there are probably a number of factors...

colder air is denser (that's why a hot air baloon rises), so heavier, denser air would have more mass, creating more force for a given velocity

but warmer air can carry more water vapor (is more humid), thus making it "thicker" . . .
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Postby Loscocco » Fri Oct 12, 2007 10:47 pm

sounds like a bunch of hot air to me. ppphhppt!!!
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Postby Bulldog » Sat Oct 13, 2007 4:24 pm

Warmer air "can" be more humid, but obviously the warm air in the Delta in the summer is much drier than the cold air on the Coast at the same time of year. The humidity in the Valley is much lower than it is in the Bay Area/Coast that time of year.

Godsey is always telling us how "cold air sticks to the water" better than hot air. Cold air is always sinking, while hot air is rising (ballon analogy again).
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