- Climate regions of California
The climate regions of California, sometimes known as the Winkler Scale or the heat summation method, is a technique for classifying the
climate ofwine growing region s. In the system, geographical areas are divided into five climate regions based on temperature, known as Regions I–V. The system was developed at theUniversity of California, Davis by A. J. Winkler and Maynard Amerine.The system
The system is based on the hypothesis that grapevines do not grow if the temperature is below 50 °F (10 °C). Days in the growing region (assumed under the system to be
April 1 throughOctober 31 in theNorthern Hemisphere ;October 1 throughApril 30 in theSouthern Hemisphere ) are assigned degree days according to the amount that the day's average temperature exceeds this threshold; one degree day per degreeFahrenheit over 50 °F. In places whereSI units are preferred, degreesCelsius over 10 °C may be used, but should be multiplied by 1.8 to convert to Fahrenheit degree days for the following list. All days in the locale are then added up, with the sum used to determine the region's classification as follows:* 2,500 degree days or less: Region I
* 2,501–3,000 degree days: Region II
* 3,001–3,500 degree days: Region III
* 3,501–4,000 degree days: Region IV
* Greater than 4,000 degree days: Region VThe system is used officially in
California , and otherUnited States growing regions such asOregon and Washington. It is less widely used elsewhere; however degree days can be computed for any location for which detailed climate data is available.Application
Different
varietal s of grapes are generally considered to best thrive in certain climate regions. Region I, the coolest, is similar toCôte d'Or and Champagne, theRhine , or the Willamette Valley inOregon ; it is well-suited to growingCabernet Sauvignon ,Sauvignon Blanc ,Chardonnay ,Pinot Noir , orRiesling . Region II is similar toBordeaux . Suitable varietals include the Region I wines, plusMerlot . Region III is similar to the Rhône, and is best suited to Sauvignon Blanc,Sémillon , orZinfandel . Regions IV and V do not correspond to any growing region inFrance ; the former is similar toSpain , and is well-suited to Port andBarbera . Region V is similar toNorth Africa , and is best suited to wines likeMuscat (grape and wine) or varietals likeVerdelho .California has growing regions which lie in all five regions; from
Napa andSonoma in the north (which lie in regions I-III) to theSan Joaquin Valley and points south, which lie in regions IV and V.Limitations
The climate regions of California only describe one aspect of an area's climate--mean daily temperature. Many other important factors which contribute to a region's suitability for viticulture (and its
terroir ) are exluded; among them sun exposure,latitude , precipitation,soil conditions, the likeliness of extreme weather which might damage grapevines, andpollution . The climate regions are also macroscopic in nature; there is often a wide variety ofmicroclimate s in a given geographical area, and a region which has marginal grape-growing weather overall may have microclimates which produce excellent grapes. A notable example is the Willamette Valley (firmly within region I), which was long regarded as too cold and wet to grow grapes; yet has vineyards planted numerous south-facing hills in therain shadow of theCoast range which produce world-classPinot Noir and many other excellent wines.More complex climate indices have been introduced to address perceived shortcomings in the Winkler scale.
References
* cite web
title=Climate regions of California
work=the wine lover's companion (online)
publisher=Epicurious
url=http://www.epicurious.com/drinking/wine_dictionary/entry?id=5931
* cite book
title=The Wine Lover's Companion
edition=2nd
author=Ron Herbst and Sharon Tyler Herbst
publisher=Barron's Educational Series
date=2003
isbn= ISBN 0-7641-2003-4
* cite book
author=Winkler AJ, Cook JA, Kliere WM and Lider LA
title=General Viticulture
edition=2nd
publisher=University of California Press
date=1974
isbn= ISBN 0-520-02591-1
* cite web
title=Ballarat's climate
work=Ballarat Wineries home page
publisher=Balalrat Wineries
url=http://www.ballaratwineries.com/climate.htm
* cite conference
author=Gladstones J.
year=2000
month=January
location=Melbourne, Australia
title=Past and Future Climatic Indices for Viticulture.
booktitle=5th International Symposium for Cool Climate Viticulture and Oenology
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