¿Por qué flotan los globos aerostáticos?

The video explains how hot air balloons work, starting with their initial flat state on the ground. The pilot uses flames to heat the air inside, causing the air molecules to spread out and the balloon to expand. Warm air is less dense than cold air, allowing the balloon to rise. The pilot maintains flight by keeping the air warm and lands by letting the air cool, making the balloon sink as the air becomes denser.

Why does warm air rise above cold air?

What occurs when the air inside the balloon cools down?