Degree day index for regional climate classification
Date or time period: 1940s
Amerine & Winkler developed a heat summation index (based on de Candolle) for viticulture in California: confined heat summation base 50°F to the period 1 April to 31 October corresponding to growing season. California growing areas were assigned to five climatic regions on this basis
- Amerine, M.A. and Winkler, A.T. (1944). Composition and quality of musts and wines of California grapes. Hilgardia (University of California) 15: 493–673.