Old Faithful Rainbow

rainbow at old faithful geyser eruption
Rainbow and Old Faithful
Rainbow formation is actually a very predictable event.  With the right alignment of light and water in the air a rainbow will happen every time.  A rainbow in Yellowstone Park can be a nice photographic companion to a geyser eruption.  Old Faithful on a sunny afternoon, later in the day when crowds have thinned a little bit demonstrates this phenomenon.

The sunshine is coming from the West.  The prevailing wind also comes from that direction.  This spreads the water into the air on the east side of the geyser.  In order to see this in the best light, I would recommend being on the south west or directly south of the geyser itself.  The effect is short lived.  You may see it for about 30-60 seconds before it disappears.  Enjoy.