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Temperature Sum=Growing Degree Days


   Wheely interesting. Most of us are familiar with "temperature sum".

  You have stumbled upon what we call "growing degree days" here in the states.
This data has been tracked for at least the last 50 years.  We have 344 climate
divisions in the contiguous 48 states.

  The growth rates of insects and plants are dependent upon the amount of heat
the organism receives. Each species, whether a crop, weed, insect, or disease
organism, is adapted to grow best over certain minimum temperatures. Scientists
have studied the minimum temperatures required for growth of many economically
important pests. This knowledge can be used to predict when pests are likely to
show up in a given area. The heat accumulation for a given base temperature
corresponding to a specific species is reported as growing degree days (GDDs)
that are cumulative within the growing season.
    In our region the GDD base temperature is 50 degrees Fahrenheit and the
growing season begins March 1. GDD is computed by taking the average temperature
on a given day and subtracting 50 degrees Fahrenheit. Each degree the average
temperature is above 50 degrees represents a growing degree day. Values greater
than 0 are accumulated beginning with March 1.

The heating and cooling industry uses heating degree days and cooling degree
days centered around 65F to calculate heating and cooling cost and to aid in the
design of temperature control systems.

Dan Nelson
Bridgeville DE
zone 7

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