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Average winddirection
Posted: Sun 14 Feb 2010 9:59 am
by nitrx
As far as I can see there is no way to calculate the average wind-direction the winddirection is measured in degrees 0 till 360 but not stored anywhere. It should be nice to store the winddirection in a value every time so calculations can be made over a given period by example the average winddirection over the month february should be the sum of all degrees divided by the total records stored in the same period.
I found the <#wdir> tag but what means 'bearing' ...?
Maybe this can be implemented in a future version of Cumulus

Re: Average winddirection
Posted: Sun 14 Feb 2010 10:21 am
by steve
If I tell you that bearing means direction, things should become clearer. So the average direction is stored in the monthly log files (the eighth field), in realtime.txt (47th field) and is also available as the <#avgbearing> web tag.
the sum of all degrees divided by the total records stored in the same period
Not so simple

- think about what the average direction is of a set of readings at 359 degrees and an equal number of readings at 1 degree. The answer isn't 180.
Re: Average winddirection
Posted: Sun 14 Feb 2010 10:33 am
by nitrx
If I tell you that bearing means direction
Well in that case I'd better asked before what means bearing

Thank you for this information I thought bearing meant something like change of winddirection (in Dutch we've krimpende and ruimende wind I couldn't find an English translation of it)
Krimpend should mean something like wind canging in direction mostly followed by a depression (low) with rain againts rotation of the clock an ruimend chanching rotation clockwise
Anyway it's clear to me no changes of cumulus are needed at this point
Not so simple

- think about what the average direction is of a set of readings at 359 degrees and an equal number of readings at 1 degree. The answer isn't 180.
You're right North isnt equal to South

Re: Average winddirection
Posted: Sun 14 Feb 2010 10:40 am
by steve
nitrx wrote:Krimpend should mean something like wind canging in direction mostly followed by a depression (low) with rain againts rotation of the clock an ruimend chanching rotation clockwise
In English we have "veering", which is a change of wind direction in a clockwise direction, and "backing", which is a change of wind direction in an anti-clockwise direction.
Someone asked recently if I could add veering and backing to Cumulus, and it's an excellent idea which I will try to do at some point.
Re: Average winddirection
Posted: Sun 14 Feb 2010 10:44 am
by nitrx
So veering sounds like bearing

well these values can be interesting for forecasting at least in my region.