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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 13:28, 30 November 2012
, 30 November 2012→Heat Degree Days
m (Explaining Heat Degree Days and Cold Degree days in Cumulus, plus how to set thresholds) |
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==Heat Degree Days==
You may have a thermostat that makes your heating come on when the temperature falls below a threshold.
Cumulus calculates the time that the temperature is below that threshold and reports it as 'Heat degree days' using the unit of ''days''. Cumulus reports this by month as part of the NOAA report. It also appears in the annual NOAA report.
So if for each day of November, there was just one hour below the threshold, the total for the month would be 30 hours reported as 1.5 days.
==Chill Hours==
A related measure, also reported by Cumulus counting the ''hours'' below a (different) configurable temperature threshold for the 12 month period starting on the 1st day of a configurable month, is Chill Hours.
The traditional way of calculating the accumulation of Chill Hours is the number of hours the temperature is below 45F or 7.5C for the period of 1st October to 30th April in the Northern Hemisphere. This is available on Cumulus as that threshold, and start date are the default, so you simply observe the reported value on 30 April.
The main 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 below 200 hours to around 1500 hours.
However, the way it can be configured on Cumulus will allow you to track air frost hours, ground frost hours or any other below the threshold parameter.
==Cold Degree Days==
You may have a thermostat that makes a cooling system come on when the temperature rises above a threshold.
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