Monthly log files: Difference between revisions

Monthly log files (view source)

Revision as of 21:17, 17 November 2013

464 bytes added , 21:17, 17 November 2013

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→‎Cumulus Wind Speed Terminology

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 === Cumulus Wind Speed Terminology ===
-How wind speeds relate to various weather stations is explained in FAQ. Basically there are 3 values stored:
+How wind speeds relate to various weather stations is explained in FAQ. Basically there are 3 values processed by Cumulus:
 #Gust - the highest wind speed over a particular period (this period defaults to 10 minutes),
 #Average - the moving average of wind speed measurements over a particular period (this period can be set to what suits you, but defaults to 10 minutes),
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 [[FAQ#What_do_the_various_wind_speeds_in_Cumulus_correspond_to.2C_with_Davis_stations.3F|FAQ: Wind speeds in Cumulus with Davis stations]], the ''EasyWeather'' differences in [[FAQ#What_do_the_various_wind_speeds_in_Cumulus_correspond_to.2C_with_Fine_Offset_stations.3F|FAQ: Wind speeds in Cumulus with Fine Offset stations]] and [[FAQ#How_do_I_set_up_recording_wind_speeds_in_Cumulus.2C_with_Oregon_Scientific_and_La_Crosse_stations| FAQ: Wind speeds with Oregon Scientific and La Crosse stations]]
-Cumulus calculates the monthly/annual/period ''average wind speed'' (as used for 'This ...' screens in '''View''' menu and the NOAA report) by trawling through the monthly logs, summing the values for the individually logged average wind speed (the fifth item ''after'' the date in each entry, column F in a spreadsheet), and dividing by the number of entries for the required calendar days. It therefore assumes that each entry has equal 'weight', i.e. each one covers the same period.  If your monthly log(s) is/are a mixture of values stored while Cumulus is running and values copied from the station logger during periods when Cumulus was not running, then it is possible the two logging intervals have not been set to the same time, so the output value could be skewed for that month/year/period.
+When Cumulus is running normally, it actually stores (in the fifth item ''after'' the date in each entry, column F in a spreadsheet) the highest (moving) average in the period since the previous logger record.  If Cumulus is not running, it stores the average from the station logger, that is the latest reported moving average. For this reason the most accurate wind speed records are achieved if Cumulus is running all day every day.
+Cumulus calculates the monthly/annual/period ''average wind speed'' (as used for 'This ...' screens in '''View''' menu and the NOAA report) by trawling through the monthly logs, summing the values for those individually logged average wind speed, and dividing by the number of entries for the required calendar days. It therefore assumes that each entry has equal 'weight', i.e. each one covers the same period.  If your monthly log(s) is/are a mixture of values stored while Cumulus is running and values copied from the station logger during periods when Cumulus was not running, then it is possible the two logging intervals have not been set to the same time, so the output value could be skewed for that month/year/period because of the difference in what was stored and the difference in the logging interval.
 [[Windrun]] is also calculated from average wind speed measurements, in this case every minute if Cumulus is running, or from the values that are logged (at station logging interval) as average wind speed when Cumulus is restarted and catches up from the station logger.