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Geyser Bows

Images by Brigitta Sipocz.

©Brigitta Sipocz

‘Rainbows’ and their supernumeraries generated by spray from the Lone Star cone geyser in Yellowstone National Park, USA

Amongst a whiff of hydrogen sulphide and other sulphurous gases, Lone Star erupts to 50ft every three hours.

Wind carried spray has a slight sting on the skin. Larger drops make a gorgeous rainbow with just a hint of a secondary too. Multiple supernumeraries testify to a narrow drop size distribution that changes as the eruption proceeds.

The bow at two stages of the eruption. The top view (shown in the top image on page) is four minutes later than the lower one (full image at left).

The top bow is noticeably broader and the supernumeraries slightly more widely spaced.

The geyser mean drop size is decreasing with time. Rainbows broaden and their colours become more pastel as drop size decreases. In extremis they become fogbows.