The Growing Environment: Climate & Weather

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 are Growing Degree Days (GDD) calculated?

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)?

Answer 3

• Model of heat summation during the growing season
• GDDs are grouped in five ranges making the data easier to use and communicate.

Question 4

What is the Huglin Index?

Answer 4

Similar formula to GDD but 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 5

What is the Mean Temperature of the Warmest Month (MJT)?

Answer 5

• 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 6

What is the Growing Season Temperature model?

Answer 6

• 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 7

What is Koppen’s Classification?

Answer 7

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)

Question 8

Describe a Maritime climate.

Answer 8

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

Question 9

Describe a Mediterranean climate.

Answer 9

• 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 10

Describe a Continental climate.

Answer 10

• 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 11

WSET temperature catogorisation

Answer 11

Cool climate = 16.5 C or below
Moderate climate = 16.5 - 18.5 C
Warm climate = 18.5 - 21 C
Hot climate = above 21 C

Question 12

What is Continentality?

Answer 12

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

Question 13

What effect does close proximity to large bodies of water have on Continentality?

Answer 13

• 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 14

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

Answer 14

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