3.4 Climate Classifications

Question 1

How is a region’s climate is defined?

Answer 1

• The annual pattern of temperature, sunlight, rainfall, humidity and wind averaged out over several years (30 years in the timescale generally agreed).
• The climate does not change from one year to the next, although it can alter over a period of decades.

Question 2

How is the Growing Degree Days (GDD) calculated? (Celsius)

Answer 2

• Subtract 10 (the temperature in Celsius below which vines cannot grow) from the average mean temperature of a month in the growing season.
• Multiply this by the number of days in that month
• Make the same calculation for each month in the growing season (April to October in the Northern Hemisphere, October to April in the Southern Hemisphere)
• Add together the totals to get the GDD. (Any months with a negative value would not be counted.)

Question 3

What is Growing Degree Days (GDD)? Who created it? When? How many zones?

Answer 3

• Who: Amerine and Winkler
• When: 1944
• Zones: V (I is cool, V is very hot)
• Model of heat summation during the growing season
• GDDs are grouped in five ranges making the data easier to use and communicate.

Question 4

How is the Growing Degree Days (GDD) calculated? (Fahrenheit)

Answer 4

• Subtract 50 (the temperature in Fahrenheit below which vines cannot grow) from the average mean temperature (in Fahrenheit) of a month in the growing season.
• Multiply this by the number of days in that month
• Make the same calculation for each month in the growing season (April to October in the Northern Hemisphere, October to April in the Southern Hemisphere)
• Add together the totals to get the GDD. (Any months with a negative value would not be counted.)

Question 5

What is the Huglin Index? Who created it? When? Where is it used widely?

Answer 5

• Who: Huglin
• When: 1978
• Similar formula to GDD
• Calculation takes into account:
  
  • • both mean and maximum temperatures
  • • increased day length experienced at higher latitudes
• The index is split into ranges, with the most suitable grape varieties mapped to each range.
• This model is widely used in Europe.

Question 6

What is the Mean Temperature of the Warmest Month (MJT)? Who created it? When? How many ranges?

Answer 6

• Who: Smart and Dry
• When: 1980
• Ranges: 6 bands (cold to very hot)
• Uses the mean temperature of either July (Northern Hemisphere) or January (Southern Hemisphere)
• Termed MJT (mean January/July temperature)
• Measures of continentality, humidity and hours of sunshine.

Question 7

What is the Growing Season Temperature model?

Answer 7

• Uses the mean temperature of the whole growing season
• Temperatures are grouped into climatic bands ranging from cool to hot.
• It is very closely correlated to GDD and is easier to calculate.

Question 8

What is Koppen’s Classification? What factors do they consider? Where do they not apply?

Answer 8

• Factors: temperature, rainfall patterns
• Majority of the world’s wine regions are categorised under three headings: maritime, Mediterranean and continental.
• Categories based very loosely on part of Köppen’s climate classification (1900)
• The categories apply to wine regions in temperate zones, not vineyards located in the tropics.

Question 9

Describe a Maritime climate. Give an example.

Answer 9

• Low annual differences between summer and winter temperatures
• Rainfall is relatively evenly spread throughout the year
• Example: Bordeaux

Question 10

Describe a Mediterranean climate. Give 2 examples.

Answer 10

• Low annual differences between summer and winter temperatures
• Annual rainfall tends to fall in the winter months, giving dry summers
• Examples: Napa Valley and Coonawarra

Question 11

Describe a Continental climate. Give 2 examples.

Answer 11

• More extreme differences between summer and winter temperatures
• Short summers and cold winters
• Temperatures rapidly changing in the spring and autumn
• Examples: Burgundy and Alsace

Question 12

What average Growing Season Temperature range (GST) defines a Cool climate?

Answer 12

Average GST of 16.5°C (62°F) or below.

Question 13

What average Growing Season Temperature range (GST) defines a Moderate climate?

Answer 13

Average GST of 16.5–18.5°C (62–65°F).

Question 14

What average Growing Season Temperature range (GST) defines a Warm climate?

Answer 14

Average GST of 18.5–21°C (65–70°F).

Question 15

What average Growing Season Temperature range (GST) defines a Hot climate?

Answer 15

Average GST in excess of 21°C (70°F).

Question 16

What is Continentality?

Answer 16

Continentality is a measure of the difference between the annual mean temperatures of the hottest and coldest months.

Question 17

What effect does close proximity to large bodies of water have on Continentality? What are the typical Koppen classifications of these regions?

Answer 17

• Closer to water = low continentality
• Typically ‘maritime’ or ‘Mediterranean’
• In winter, body of water provides a warming effect on the surrounding air
• In summer, body of water provides a cooling effect.

Question 18

If a vineyard site is farther inland or protected from ocean influences, what does it mean for the Continentality?

Answer 18

• Far inland or protected from ocean influences = high continentality
• Typically ‘continental’.