Are you sure clouds actually reduce warming? My understanding was that since they retain heat through the night, but only reflect light in the day, they actual

Are you sure clouds actually reduce warming? My understanding was that since they retain heat through the night, but only reflect light in the day, they actually exacerbate warming. That's why it's thought that airplane contrails contribute to warming, since they increase cloud cover. Could be wrong though; I don't recall where I read that exactly.