Shallow, but thick fog across southeast Minnesota early this morning resulted in what is known as a "fog bow".
A fog bow is similar to a rainbow, developing as a result of refractions in suspended water droplets. However, the fog droplets are much smaller than those of rainbow inducing raindrops - smaller than 0.05 millimeters (0.0020 in). This results in very weak colors, with a red outer edge and bluish inner edge. If small enough (like in this picture), fog bows appear white, and are therefore sometimes called "white rainbows".