Climate Definitions

Question 1

How is region’s climate defined?

Answer 1

• the annual pattern of temperature, sunlight, rainfall, humidity and wind averaged out over several years (30 years is the generally agreed upon timescale)
• 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

1. subtract 10 (the temperature in C below which vines cannot grow) from the average mean temperature of a month in the growing season
2. multiply this by the number of days in that month
3. make the same calculation for each month in the growing season (4-10/10-4)
4. 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?

Answer 3

• model of head summation during the growing season
• GDDs are grouped in five ranges, making the data easier to use and communicate

Question 4

What is the Hughlin Index?

Answer 4

Similar to GDD, as the calculation takes into account:

• both mean and max temps
• increased day length experienced at higher latitudes

The index is split into ranges, with the most suitable varietals mapped to each range. 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 temp of either July (N. hemi) or January (S. hemi)
• 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
• temps are grouped into climatic bands ranging from cool to hot
• very closely correlated to GDD and is easier to calculate

Question 7

What is Koppen’s Classification?

Answer 7

Factors: temperature, rainfall patters

• majority of the world’s wine regions are categorized under three headings: maritime, Mediterranean, and continental
• categories based very loosely on part of Koppen’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

e.g. 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

e.g. 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 spring and autumn

e.g. Burgundy and Alsace

Question 11

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

Answer 11

average GST of 16.5 C (62 F) or below

Question 12

What average GST range defines a moderate climate?

Answer 12

average GST of 16.5-18.5 C (62-65 F)

Question 13

What average GST range defines a hot climate?

Answer 13

average GST in excess of 21 C (70 F)

Question 14

What is Continentality?

Answer 14

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

Question 15

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

Answer 15

• 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 16

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

Answer 16

-far inland or protected from ocean influences = high continentality (typically continental)