Gloria

Observed in the clouds in front of the observer or below, at a point directly opposite the light source. The observer must be on the mountain or on the plane, and the light source (Sun or Moon) behind him. Is a colored halo of light on the cloud around the shadow of the observer. Inside is a bluish ring on the outside is reddish, then the ring may be repeated with less intensity. The angular size is much smaller than the rainbow — 5...20°, depending on the size of the droplets in the cloud.
Gloria is due to the diffraction of light, previously reflected in the droplets of the cloud so that it is returned from the cloud in the same direction, which was falling, that is, to the observer.

Translated by «Yandex.Translator»