Why does hot air always go to the cold air?

Hot air rises because it is less dense than cold air, creating an upward buoyant force. As hot air ascends, it creates a low-pressure area that draws in cooler, denser air to fill the space. This movement of air is a fundamental principle of convection, where warmer air replaces cooler air, leading to a continuous cycle of heat transfer. Ultimately, the mixing of hot and cold air helps to equalize temperatures in the environment.