Fold the piece of tissue in half length wise. Then unfold and fold each edge over to the middle so their are three creases. This will allow you to form a triangular column which will stand up. Just as the flame reaches the bottom, the resulting ash will be lifted upward by the rising hot air, dramatically showing convection of heated air. A hot radiator on the floor can heat much of the room as the heat is convected around.
Wind is caused by the rising of air heated by the ground which has been heated by the sun.