Heat/cold degree days and Chill hours: Difference between revisions

Heat/cold degree days and Chill hours (view source)

Revision as of 21:34, 30 May 2013

123 bytes added , 21:34, 30 May 2013

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→‎Chill Hours and/or Air Frost: Minor re-sequencing for easier readability

Sfws

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 ==Chill Hours and/or Air Frost==
-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'''.
+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'''.  This measure is sometimes called ''Growing Degree Days'', because it relates to plants or insects rather than heating systems.
 === Calculation of Chill Hours ===
 The traditional way of calculating the accumulation of Chill Hours is the number of hours the temperature is below 45 degrees Fahrenheit or 7.5 degrees Celsius for the period of 1st October to 30th April in the Northern Hemisphere.  On Cumulus that threshold, and start date are the default, so you simply observe the reported value at the relevant time on 30 April. The current figure is viewable on the 'This Year' screen accessed from the View menu (only when the current year is selected), and is available via web tag <#chillhours> to be added to a web page template of your design.
-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.
+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 below 200 hours to around 1500 hours.
-However, the way it can be configured on Cumulus will allow you to track air frost (defined as when temperature at the standard measuring height is below the freezing point for water) hours, ground frost (temperature close to ground level is below freezing) hours or any other measure being below the threshold parameter.
 [[User:Sfws|Sfws]] 10:53, 1 December 2012 (UTC) (with thanks to Randy who raised Enhancement Request #117 and supplied some of the above text)
 === Air Frost ===
-To see the number of '''Air Frost days''', use the View menu to select 'This Month', 'This Year' or 'This Period' and choose the precise period of interest using the drop down selectors. (As at build 1058, there are no web tags to give air frost day counts). The Chill hours web tag with a threshold of 0 degrees Celsius (32 Farenheit) will give '''air frost hours''' since the starting month.
+However, the way it can be configured on Cumulus will allow you to track air frost (defined as when temperature at the standard measuring height is below the freezing point for water) hours, ground frost (temperature close to ground level is below freezing) hours or any other measure being below the threshold parameter.
+To see the number of '''Air Frost days''', use the View menu to select 'This Month', 'This Year' or 'This Period' and choose the precise period of interest using the drop down selectors. (As at build 1058, there are no web tags to give air frost day counts).
+The Chill hours web tag with a threshold of 0 degrees Celsius (32 Farenheit) will give '''air frost hours''' since the starting month.
 ==Cold Degree Days==