it always struck me as odd how much more activity there seemed to be in the hives on bright sunny days vs days where it was a little cloudy or even broken occasional clouds.....
I think that's true though. I've observed them not flying during warmer temps with cloud cover and no sun, and watched them fly during cooler temps but with full bright sun. Talking like 45*F vs. 35*F. I was right next to the hive though, so no shadows. lol
Well, it's my first winter with them and we've had tons of snow, even down here in the valley. They were confined inside for a good month or more, when they finally had a break and got some relief. For a week there I observed a large amount of dead bees each day in front of their hive. It was still very cold though. Maybe in the low teens. I really didn't know how many dead was too much but it just seemed like too much each day. I spoke with a uk beek I know who told me the sun was probably so brightly reflecting off the snow, they definitely thought it was warmer than it was, tried to fly to cleanse, and perrished. That was my AHA! moment. He told me to shade the entrance and that solved that.