I'm looking for a better and more simple explanation of the term that Winkler scales uses - like degree days, etc...
Is someone have something or can explain it by himself?
Okay I'll do my best...
The "Winkler Scale" is also know as the California Heat Summation Index and is based on the idea of a "degree day." 50 degrees F is generally considered the minimum temperature for vine development, and is therefore used as a baseline. The scale is the sum of all average temperatures during the growing season, from April 1 through October 30, minus the 50F baseline.
Degree Day = (High Temp + Low Temp)/2 - 50
The sum of each Degree Day throughout the season gives you total Growing Degree Days (GDD). Specified ranges are what is used to classify the regions (1-5) of the Winkler Scale.
Here's a link to an article discussing the Limitations of the Winkler Index for your reading pleasure.