"sun is just too loud" I get that completely. For me, sometimes even gravity pisses me off. I sometimes get to the point of not being able to hold it in too. I'm embarrassed after the fact, but in the moment, Heaven help whoever gets in my way. Or brushes past me. Or looks in my direction. Or exists.

I believe in my case, it's largely anxiety related. Will someone pull out in front of me at the intersection. Will someone take 'my' parking spot. What if someone bumps in to me. etc.
Anxiety that any of a thousand things I'm thinking in my head may happen. Anxiety from how I may deal with it.