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Heat/cold degree days and Chill hours: Difference between revisions
Heat/cold degree days and Chill hours (view source)
Revision as of 18:34, 5 November 2014
, 5 November 2014→Calculation of Chill Hours
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The traditional way of calculating the accumulation of Chill Hours is the number of hours the temperature is below 45 degrees Fahrenheit or 7.2 degrees Celsius for the period of 1st October to 30th April in the Northern Hemisphere. One applicability is to stone and seed fruit as their exposure to low temperatures during the winter months will have a significant effect on the following harvest. Too few cold hours can result in poor quality and quantity of the crop. Fruit tree varieties prefer a Chill Hour rating from about 200 hours to around 1500 hours.
On Cumulus that threshold, and start date are the default, so you simply observe the reported value at the relevant time on 30 April/1 May. To use a different threshold add ''ChillHourThreshold=x.x'' to [[Cumulus.ini#Section:_Station| station section in Cumulus.ini]] where x.x is the temperature you want in your normal Cumulus temperature units. Use ''ChillHourSeasonStart=mm'' in [[Cumulus.ini#Section:_Station| station section in Cumulus.ini]] where mm represents month number (1=January, 12=December) to change the season start. The current figure is viewable on the 'This Year' screen accessed from the View menu (only when the current year is selected), stored in [[today.ini]], and is available via web tag <#chillhours> to be seasonal or longer period added to a web page template of your design. Should you miss checking the reported value on 1 May, then for a few days, you can look in the backup sub-folder for the necessary archived today.ini. In the current version of Cumulus, a new archive of the data sub-folder is taken just after each rollover, but note that Chill hours are counted in Cumulus by calendar day (therefore some interpolation is needed if your rollover is 9am/10am).
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