When opening a bottle of soda or champagne, a white cloud forms due to the sudden expansion of bubbles, which leads to adiabatic cooling. This process is thermodynamically allowed as the equalization of pressures increases entropy by providing more distribution possibilities for molecules. The cooling can cause some water vapor to condense, creating the visible cloud. On warm, dry days, this cloud may not be as noticeable. The explanation confirms the initial thoughts on the phenomenon.