From a physical point of view, the wine liquid covers the wall of the cup, the contact surface with the air increases, and the evaporation effect is enhanced. The boiling point of alcohol is lower than that of water. It evaporates first, forming an upward pulling force. At the same time, because water has a higher surface energy per unit area than alcohol, as the alcohol concentration decreases, the surface energy of the wine will increase, and the surface tension will increase. Larger, the adhesion on the wall of the cup also increases, so the wine accumulates everywhere to form an arch. Due to the action of gravity, gravity finally wins and destroys the tension on the surface of the wine, causing the wine to slide down.