Fire rainbow over Grand Rapids
© Ellen Bacca
Ellen Bacca took the pic. above in downtown Grand Rapids Monday. It's a "fire rainbow" also known as a circumhorizontal arc.

It's actually not a rainbow caused by rain and you would be looking at a rainbow with the sun at your back. This occurs when sunlight passes through a band of high clouds with 6-sided crystals in the shape of plates.

The sun has to be at least 58 degrees above the horizon to see a circumhorizontal arc. That means today (one day from the Summer Solstice) you could see a circumhorizontal arc between 11:41 am and 3:50 pm and in Grand Rapids you can only see a fire rainbow from April 18 to August 23rd, when the sun climbs to 58 degrees above the horizon.

North (and south) of 55 deg. latitude, you'll never see a fire rainbow. In London, England (51.5 deg. latitude), they only have a total of 140 hours a year when the sun is high enough to see a circumhorizontal arc.

This awesome pic. of a circumhorizonal arc is on the Wikipedia page. I've got more in a previous article I wrote on the topic last August, along with more pics.
Fire rainbow