I recall being told that Hawking radiation happens when matter/anti-matter spontaneously appears when straddling an event horizon. The Universe full of matter/

I recall being told that Hawking radiation happens when matter/anti-matter spontaneously appears when straddling an event horizon. The Universe full of matter/anti-matter bubbles popping in and out of existence. Most of them don’t straddle an event horizon but they still occur. How much would such a fog contribute to the darkness at night? Edit: Aha, clouds are irrelevant. Any dark clouds would heat up until they are the same brightness as the rest of the sky. Thanks, article!