Chill hours
The displayed values are calculated using the following four models ( See documentation ):
Hours below 45°F
It simply counts the number of hours that average temperature is less than 45°F
Hours between 32°F-45°F
Like the previous method, counts number of the hours that average temperature is between 32°F and 45°F
Utah model
A little more complex method that assign a different value ( unit ) at each temperature:
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below 34°F = 0.0 chill unit
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between 34.01 - 36°F = 0.5 chill unit
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between 36.01 - 48°F = 1.0 chill unit
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between 48.01 - 54°F = 0.5 chill unit
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between 54.01 - 60°F = 0.0 chill unit
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between 48.01 - 60.01 - 65°F = -0.5 chill unit
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over 65.01°F = -1.0 chill unit
Dynamic model
A more complex method ( See documentation ), developed by EREZ, A. and FISHMAN, S. - The Volcani Center, Bet Dagan, ISRAEL
