In Yami's scenario of heating cocoa, where is convection best observed?

Convection is best observed in the rising steam from the cup of cocoa because it demonstrates the movement of liquid or gas due to temperature differences. When the cocoa is heated, the molecules of the liquid become more energetic and start to move apart, causing the warmer, less dense areas to rise. As the steam rises, it carries away heat and is replaced by cooler, denser air from the surroundings. This process of warmer fluids rising and cooler fluids sinking is a hallmark of convection currents.

In contrast, stirring the cocoa involves mechanical energy input, which homogenizes the mixture rather than illustrating natural convection. Touching the warm handle of the cup is related to conduction, as heat transfer occurs through direct contact. Blowing on the hot cocoa can create movement of air, but this action itself does not exhibit convection; rather, it may cool the surface of the liquid. Thus, rising steam effectively demonstrates convection by showing how heat transfer can move through fluids in a natural way.