A typical summer day unfolds in the Colchagua Valley as a powerful sun rises over the vineyards in the Andean foothills that form the regionâs eastern edge. Hours later, that same sun will become a fireball in a cloudless azure sky. Below, on the valley floor and up the craggy hillsides that mark the southern and northern boundaries of Chileâs most textbook wine valley, Cabernet Sauvignon, Carmenère and other vines soak up potent solar rays on their way to eventual ripeness.