Not all arches in the sky are filled with colors. Here we see a fog bow arcing over the Golden Gate Bridge in San Francisco, Calif., on Nov. 15, 2006. The principle of formation for a fog bow is similar to a rainbow, as the fogbow is a reflection of sunlight. However, as NASA describes it, the lack of relative colors are due to the relatively smaller water drops. “The drops active above are so small that the quantum mechanical wavelength of light becomes important and smears out colors that would be created by larger rainbow water drops acting like small prisms reflecting sunlight,” writes NASA. The right end of the fog bow appears to dip right into the top of the Golden Gate Bridge.