Scientists study Sierra Nevada ponds that change 20°C in a day

High in California's Sierra Nevada mountains, small ponds may look peaceful and unchanged. Surrounded by rocky peaks and open skies, they appear calm during summer. But beneath the surface, these shallow water bodies are constantly changing.A new study has found that these mountain ponds are among the most thermally variable freshwater ecosystems on Earth. Their water temperature can change by more than 36 degreen F or 20 degrees C within a single day. Researchers say one major factor behind these dramatic changes is not summer weather, but the amount of snow that fell months earlier during winter.The study, published in the journal Ecosphere, reported by Science X, found that winter snowpack plays a key role in deciding how these ponds behave during summer. It affects their size, water temperature, nutrient levels and even the tiny animals living in them.