This cool climate, with its marginal sunlight, force the vine to struggle to produce grapes. This struggle ensures that well-handled vines give bounty which reflects this vibrancy in the face of adversity. These conditions have been recognized through the centuries as the basis for the production of the finest Riesling grapes.
The slate-filled vineyards are situated at up to 60° exposure to the sun. The dark slate heats up faster than do other soils; the river's warmth both ameliorates temperature variations and reflects the sunshine to the leaves (their sugar factories), therefore maximizing their ability to benefit from the river.
Another peculiarity is that these river valleys are bookended by the Hunsrück and Eifel mountains whose high, cool air flows at night into the valleys to chill the grapes. This aspect contributes to acidity retention, helping to create an intense spectrum of aromas and flavors.
In autumn the reaction of the cool air upon the warmer river water creates morning fog with the resultant dew settling upon the grapes. This is an environment which encourages the spread of the mold botrytis cinerea ('noble rot' or, in German, 'edelfäule') necessary for the world's most prized sweet wines.

