BOSTON — You may have seen colors in the sky today, like in these pictures sent in by viewers today.
Commonly known as a "fire rainbow," the technical term for this rainbow in the clouds is a Circumhorizontal Arc.
It is formed when a sun that is just high enough (at least 58 degrees above the horizon), so you won’t see one in New England in winter. You also have to have clouds made from hexagonal ice crystals.
Typically, those wispy cirrus clouds like we had Tuesday. Those ice crystals also have to be oriented horizontally, or flat with respect to the ground.
The high sunlight enters the crystal from the side and is refracted, leaving the crystals from the horizontal base. Fragmented cirrus clouds can give the look of a rainbow-colored flames.
Cox Media Group