I was strolling on Union Square, saw this ... burst of energy suddenly appear right before my eyes!
At the time, i was shocked, it was so unbelievable! Reached for the camera, got this shot!
Now looking back,
i think it's because the fog (SF is famous for it) was quite low,
and the late afternoon sun from above was still shining into the windows,
and reflected back into the fog, hence the rays.
As the fog passed over really fast, the sun was blocked, and the rays disappeared.
Altogether, just a few minutes -- seconds even! -- of a stunning phenomenon!

Union Square, San Francisco