Yellowstone — Grand Prismatic Spring Aerial

Description

The Grand Prismatic Spring in Yellowstone’s Midway Geyser Basin measures 91 metres in diameter — the third-largest hot spring on Earth — and is most famous for its extraordinary colour pattern visible only in aerial photographs: deep blue at the boiling centre (100°C, too hot for any microbial life), surrounded by progressively coloured rings of thermophilic bacteria that range from yellow to orange to red as temperature decreases from the spring’s edge outward. This photograph was made from a helicopter at 150 metres altitude in conditions of full cloud cover — paradoxically optimal, as direct sunlight creates glare on the water surface that obscures the bacterial mats below. The steam rising from the boiling centre creates a vapour column that required precise timing to avoid concealing the spring structure. The complete spectrum from blue to red is visible in a single frame.