Author Topic: Dominant vs Average Wind Direction  (Read 3806 times)

ELO

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Dominant vs Average Wind Direction
« on: April 29, 2013, 04:33:31 AM »
How is Average Wind Direction calculated? Is it simply the average of all the wind directions recorded regardless of wind speed? Are dead calm (zero wind speed) data points included? I ask because I have finally repaired my wind vane and find the average wind direction numbers difficult to believe in the context of where the wind seems to come from all day.

It appears that Dominant Wind Direction is a much better indicator based on personal observation and perhaps a better representation of reality since it seems to take wind speed into account. For instance, on 27 April, my average wind direction was 152?, while the Dominant wind direction was 300?. I'll assure you that the wind was not generally from the SE on the 27th! Today (28 April) through 9pm, my average is 210? and my dominant is 310?. I'm not sure what average wind direction really means when I see a 152? average but know and can see on the charts that any wind above about 2-3 mph came from the NW or thereabout all day. The Dominant wind calculated for that day was much more representative at 300?.

If Dominant is a better representation of general wind direction over a day, month, etc. would it make sense for the dominant direction to be used in the recent, monthly, and year over year stats instead of average wind direction?

Rick
 :-\

KeithC

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Re: Dominant vs Average Wind Direction
« Reply #1 on: April 29, 2013, 09:00:40 PM »
Hi Rick.

Just an educated guess but I would think that "average" direction would average the degrees (e.g. 360 degrees == north) to get a numeric degree heading, whereas "dominant" would be a function of time, meaning the dominant direction would be the direction the vane pointed to for the longest cumulative duration of time within a given time span (say ten minutes).

I hope that a more knowledgeable someone will chime in on this.

Keith