Upgrade your winter wardrobe to enjoy all of the benefits of crop tops even in the middle of the winter. First invest in some warmer clothes that are cropped and short but long-sleeved and thicker then summer crop tops like cropped sweaters, hoodies etc. Layer several of them to keep everything else warm and comfortable while your belly is free :) Second open your winter jacket or coat and enjoy your winter bare midriff outfit. If it's very cold and after some time your belly can't take it any more just close your jacket/coat to protect your tummy from cold, but try to not overdo it, be brave xD