On a summer afternoon in the Sierra Nevada, a mountain pond can look calm and still, reflecting granite peaks and alpine sky. But beneath the surface, these small, shallow waters are anything but stable. In fact, they are among the most thermally variable aquatic ecosystems on Earth, with water temp eratures sometimes swinging more than 20°C (36°F) in a single day. According to new research published in the journal Ecosphere, the force driving much of that variability begins months earlier: winter snowfall. ...read more read less