I took this snapshot from our Orange Beach camera this morning shortly after 6:00.
This beautiful pre-sunrise moment is called a cloud shadow. A very thin layer of clouds high in the upper atmosphere acts like a screen; a thicker cloud is just beyond the horizon. Because the pre-sunrise light is low in the sky, the thick cloud casts a shadow on that screen and the result is this lovely weather phenomenon.
Cloud shadows can happen at sunset, too, so keep looking up!