The Color of Heat

The intense blue color at the center of Grand Prismatic Spring in Yellowstone National Park is a result of water temperatures as high as 189 degrees. Not much can live at temperatures this extreme, so the water is very clear. As the water cools near the edges of the spring, conditions become just right for single-celled thermophiles that can generate energy through photosynthesis.

Green chlorophyll is the primary pigment for photosynthesis, but under harsh conditions other pigments are produced. Instead of green, they are yellow, orange, and red, giving the vibrant rings of color seen around the edge of the spring. In cooler water the bacterial diversity increases dramatically, creating orange and reddish-brown areas. It is amazing to me how the cellular processes in these microorganisms paint the landscape in such vibrant colors.