This morning as I sat at my computer desk reading the forum the sun appeared once again!!! While reading my favorite guy's postings I heard a CRACK! It was the sun that caused the glass in my window to start heating up, and at some point the expansion force "snapped" which I interpreted as a loud CRACK! Can someone explain that crack to me? ...Is there any possibility that what causes that crack is somehow linked to what causes thunder, just on a smaller scale?