What characteristic of Sonoma Mountain contributes to its grape growing conditions?

Sonoma Mountain's high altitude with fog-free exposure is a significant characteristic that positively impacts grape growing conditions. The elevation allows for cooler temperatures, which can help preserve the acidity in grapes and promote the development of complex flavors. Moreover, being above the typical coastal fog that rolls in can lead to increased sunlight exposure during the day. This combination of factors enables the grapes to ripen more evenly and thoroughly, fostering an ideal environment for cultivating high-quality wine grapes. The conditions encourage balanced growth and the ability for varietals to mature optimally, which is crucial for producing premium wines.

In contrast, the other options describe conditions that would generally be less favorable for grape growing, such as excessive humidity or low sunlight, which can lead to disease pressure and inadequate grape development. Therefore, the unique combination of altitude and exposure on Sonoma Mountain plays a vital role in creating ideal conditions for viticulture.