Climate and Weather Flashcards
What is Climate?
The long-term regional pattern of weather, usually established over a 30 year history.
What is Weather?
The daily pattern of localized atmospheric changes, primarily temperature, precipitation, and wind.
How are Macroclimates classified?
Average temperature of the growing season and continentality (difference between average temperature of the hottest and coldest months)
Cool Climate temperature range
Average temperature of <16°C
Moderate Climate temperature range
Average temperature of 16.5°C-18.5°C
Warm Climate temperature range
Average temperature of 18.5°C-21°C
Hot Climate temperature range
Average temperature of >21.5°C
The description of climate zones was introduced by whom and when?
Wladimir Köppen, 1900
Which climate zone does the Vitis genus find comfort in?
Temperate zone
What are the three most important subzones for Vitis Vinifera cultivation?
Maritime
Mediterranean
Continental
What are the characteristics of the Maritime climate?
Typically found near large bodies of water
Low annual range of temperatures
Higher rainfall averages (typically during the growing season), thus more cloud cover
Risk of excessively low summer temperatures
Risk of spring frost and cool/wet conditions at fruit set
Ideal for production of medium bodied wines with moderate alcohol
What are the characteristics of the Mediterranean climate?
Low annual range of temperatures
Dry summers and rainfall in the winter
Ideal for production of full bodied, richly textured red wines with ripe tannins
What are the characteristics of the Continental climate?
Areas are inland and isolated from influences of large bodies of water
Wide annual range of temperatures (hot/warm summers, cool/cold winters)
Uniform annual precipitation but drier than maritime climates
Shorter growing season due to rapid temperature drop in Autumn
What are the characteristics of a Tropical climate?
Minimal temperature variation
Seasons defined by rainfall
Vines do not receive temperature signals for dormant/growth cycles, may crop more than once per year
Generally unsuitable for quality viticulture even in zones moderated by altitude or oceans
What is the primary climatic control of grapevine growth?
Temperature
What is Heat Summation?
The total number of heat degree days (HDDs) calculated by
The Monthly Mean Temperature minus 10°C multiplied by the Number of Days in the Month
with the average of each month of the growing season added together.
Who invented Heat Summation and when was the concept published?
Amerine and Winkler, 1944, for matching cultivars with appropriate heat zones in California
What is a Growing Degree Day?
An alternate name of Heat Degree Day.
What are Amerine and Winkler’s degree day region classifications?
Category 1 | <1370°C
Category 2 | 1370°C - 1650°C
Category 3 | 1650°C - 1930°C
Category 4 | 1930°C - 2200°C
Category 5 | >2200°C
What is the Heat Summation of Category 1 and what is it good for producing?
Name some regions in this category.
<1370°C
Light bodied white wines
Chablis, Mosel, and Champagne
What is the Heat Summation of Category 2 and what is it good for producing?
Name some regions in this category.
1370°C - 1650°C
Medium bodied red wines
Napa Valley, Bordeaux, and Northern Rhône
What is the Heat Summation of Category 3 and what is it good for producing?
Name some regions in this category.
1650°C - 1930°C
Full bodied red wines
Barossa Valley, Stellenbosch, and Southern Rhône
What is the Heat Summation of Category 4 and what is it good for producing?
Name some regions in this category.
1930°C - 2200°C
Fortified Wines
What is the Heat Summation of Category 5 and what is it good for producing?
Name some regions in this category.
> 2200°C
Adapted for bulk wines, table grapes, and drying grapes
What is the limitation of applying Heat Summation as defined by Amerine and Winkler?
It is less successful in regions with less reliable temperature, sunlight, and humidity than California. It is also important to note that the relationship between vine growth and temperature is not linear, with growth slowing significantly over 30°C.
What are Biologically Effective Degree Days, who introduced it, and how are they different from Growing Degree Days?
A modification of Growing Degree Days by Gladstones in 1992 that groups cultivars by ripening times. It applies a 19°C cutoff temperature in the monthly average mean temperature to provide a best-fit for cultivars across different regions.
What is the Mean Jan/July Temperature (MJT)?
The most widely used alternative to HDD developed by Smart and Dry in 1980. It uses the mean temperature of the warmest growing month with corrections for continentality, sunlight hours, day length related to latitude, humidity, rainfall, and evaporation.
What is Growing Season Temperature (GST)?
A system designed by Jones et. al. in 2005 to categorize growing regions by average temperature across the growing season, enabling comparisons of regions, wine styles, and quality to be drawn. It shows what grapes are able to ripen in specific conditions and why.
What factors influence regional climate (Macroclimate)?
Latitude
Altitude
Mountain Ranges
Ocean Currents
What effect does Latitude have on Macroclimate?
Atmosphere diffuses solar radiation. The latitudinal range of 30° to 50° on either side of the equator provides sufficient diffusion that Vitis vines can photosynthesize without stress.
Lower latitudes do not diffuse enough light while higher latitudes diffuse too much light.
Day length is also longer at lower latitudes, allowing for longer periods of photosynthesis and lower likelihood of heat and water stress.
What effect does Altitude have on Macroclimate?
Temperature drops by about .6°C per 100 meters of elevation.
Higher altitudes are, therefore, preferable at lower latitudes.
What effect do Mountain Ranges have on Macroclimate?
Mountains cast a rain shadow that prevents moist air from reaching vineyards on the leeward side of a mountain. The air condenses and precipitates on the windward side, rises above the mountain and then warms and descends the leeward side.
Aside from being a rain shadow, what is an additional benefit of the Andes?
It is a source of irrigation from snow melt that can be usefully channeled during the summers.
The absence of significant mountain barriers across parts of Europe and the Mediterranean Sea has what effect on the viticultural climate?
The change to a Continental climate from a Mediterranean climate is more gradual.
What effect do Ocean Currents have on Macroclimate?
They bring warming or cooling influences to broad areas.
Describe the Gulf Stream and its effect on grape growing.
A current that starts in the Gulf of Mexico and branches into the Atlantic Current. It warms Western Europe to 11°C above the latitudinal average, making viticulture possible in Germany, England, and Wales.
Describe the Benguela Current and its effect on grape growing.
A current that starts in Antarctica and flows along the west coast of South Africa to cool vineyards along the coast.
Describe the Humboldt Current and its effect on grape growing.
A current that starts in Antarctica and flows along the west coast of Chile to cool vineyards on the coast and in areas the wind can access via gaps in the coastal mountain ranges.
Describe the California Current and its effect on grape growing.
A current that flows south along the west coast of North America, bringing thick morning fogs that offer protection from sunlight and heat.
What is Aspect?
The direction a vineyard slope faces