Climate and Site Selection
What this domain tests
Climate and Site Selection tests the difference between macroclimate, mesoclimate and microclimate, and how temperature, radiation, water balance, frost, hail and topography determine variety choice and vineyard layout. Questions often ask you to compare two sites or explain why a site needs a particular training or irrigation strategy.
Climate scales and heat summation
Macroclimate is regional, mesoclimate is the climate of a valley or slope, and microclimate is the immediate vine canopy or soil environment. Growing degree days (GDD) sum daily mean temperatures above a base, commonly 10 °C for grapevines. Winkler regions use heat summation to classify sites; the Huglin index also incorporates maximum temperature and latitude. In Cyprus, coastal influence, altitude and aspect modify a generally hot, dry Mediterranean climate.
Site factors
Aspect controls radiation and warming: south-facing slopes are hotter and advance phenology, while north-facing slopes are cooler and may delay ripening. Slope improves air drainage and reduces frost risk on exposed sites, but steep slopes increase erosion and machinery difficulty. Altitude cools nights and can preserve acidity. Hail, strong wind, spring frost and limited water supply are major hazards. Soil water-holding capacity interacts with climate: a hot site with shallow soil needs irrigation sooner.
Worked example
Site A has a daily mean of 23 °C for 150 growing days. GDD above 10 °C ≈ (23 − 10) × 150 = 1,950 degree-days. Site B averages 20 °C for the same period, giving 1,500 degree-days. Site A is substantially warmer and suits later-ripening varieties only if water and canopy management prevent excessive stress; Site B is safer for varieties that retain acidity.
Traps that cost marks
Do not mix Celsius and Fahrenheit heat sums. Do not use the wrong base temperature. Do not confuse a regional climate statistic with a vineyard microclimate. Do not assume altitude always means cooler fruit at every hour; aspect and air drainage can reverse the expectation.
Key points
- Macroclimate, mesoclimate and microclimate operate at different scales.
- GDD uses a defined base temperature, commonly 10 °C.
- Aspect and slope modify temperature, radiation, frost risk and erosion.
- Altitude can preserve acidity through cooler nights.
- Site choice must match variety, water supply and hazard exposure.