Erica's Answer:
Sunlight heats the Earth's surface, which in turn heats the air directly above ground. The warmer air starts to rise, which displaces the air above it. So, on windy days, bright sunshine further enhances windy conditions. The sunlight adds another element of instability to a windy day. As the sun sets, the source of instability is removed, so the winds relax a little.- Erica
