Details from one of the many springs and geysers along the trail in Yellowstone National Park. The color of the algae varies based on the water temperature.  Basically the "cooler" the color of algae is (e.g., blue, green) the *hotter* the water. The yellow and orange algae is present where the water is coolest.

Shades of Heat
Details from one of the many springs and geysers along the trail in Yellowstone National Park. The color of the algae varies based on the water temperature. Basically the "cooler" the color of algae is (e.g., blue, green) the *hotter* the water. The yellow and orange algae is present where the water is coolest.