Why do soap bubbles fly into the sky?

Principle: The blown air is hot air, which makes soap bubbles fly into the sky.

Soap bubbles are hot air blown from the mouth at first, and the soap film separates them from the outside, forming two areas, the inside and the outside. The temperature of indoor hot air is higher than that of outdoor air. At this time, the density of the gas in the soap bubble is less than that of the outside air. According to Archimedes' principle, the buoyancy of soap bubbles is greater than their gravity, so they will rise. This process is the same as a hot air balloon.