sunbeam
Sunbeam or crepuscular rays are light rays that stream through gaps in clouds or between other objects. (See Danbooru post #438675 Danbooru post #336275)
Sunlight is the light that apparently or observably comes from the sun in the sky. (See Danbooru post #5469)
Sunburst is for designs or figures of burst of sunlight, but may not necessarily be the actual sun. (See Danbooru post #645306)
For tagging purposes, keep in mind that a particular image may satisfy one or more of the specific terms mentions above.