Vineyard climate – The "rules"

Climate and soil both affect the growth, quality, taste and character of a wine, but vineyard climate plays the most important role.  

Elevation
The vine needs light and warmth. But why then, does good wine mostly grow in (river) valleys? The answer lies in the temperature. This determines the maximum elevation of wine-growing. In the Rheingau this limit lies at around 300 m. For each 100 m gain in elevation, the air temperature cools by about 0.7 °C causing a must weight loss of 3 to 5 °Oechsle.

Exposition and inclination – the orientation towards the sun
Wine requires many sunshine hours to ripen fully. South-facing slopes with a higher incidence of solar radiation and higher temperatures are clearly the best sites. Under our climatic conditions, the cool north and east-facing slopes are not used for wine-growing. The angle of incidence of the solar radiation also has an effect on the warmth of the site. A slope receives up to 30% more energy.
Whilst the grapes are still growing, this difference has only little effect. However, it can be substantial during the crucial ripening process of the grapes.  

Topography – The path of the air
Cold air leads to ripening losses. Cold air is produced over higher ground on clear nights. This heavier air streams down the slope and collects in the lower regions. Therefore, river valleys are colder and wetter. Here dew is formed earlier and moisture evaporates much later from the leaves than on the slope, where the wind lets the leaves dry quicker.

The degree of ripeness required to produce high quality wines can only be achieved on warm and protected sites. Just like here along the Main River, something the Romans already knew.

But why is the land along the Main and Wickerbach so suitable for growing wine? Which factors affect the excellence of a vineyard? And how is this affected by the proximity of the Taunus Mountains?