White and/or gray patch, sheet or layered clouds, generally composed of plates, rounded masses or rolls. They may be partly fiber-like.

When the edge or a thin semitransparent patch of altocumulus passes in front of the sun or moon a corona appears. A Corona is the outermost part of the sun’s atmosphere.  This colored ring has red on the outside and blue inside and occurs within a few degrees of the sun or moon.