 The high @-@ mass air well design attempts to cool a large mass of masonry with cool nighttime air entering the structure due to breezes or natural convection . In the day , the warmth of the sun results in increased atmospheric humidity . When moist daytime air enters the air well , it condenses on the presumably cool masonry . None of the high @-@ mass collectors performed well , Knapen 's aerial well being a particularly conspicuous example . 
