Heating a parcel of air at constant pressure will result in what behavior of the parcel?

• A. It will sink
• B. It will rise
• C. It will expand
• D. It will condense

Answer: (B)

When a parcel of air is heated at constant pressure, two main behaviors occur: it will expand and become less dense, which contributes to its tendency to rise.

Heating causes the air molecules to move faster, resulting in an increase in the kinetic energy of the air parcel. As the temperature increases, this energy leads to an increase in volume due to the expansion of the air. While it is also true that a parcel of air may rise because it becomes less dense than the surrounding cooler air, the primary focus on the behavior of the parcel in response to heating is its expansion.

Though the rising behavior is closely associated with this expansion, it's important here to emphasize the key concept that heating at constant pressure leads to an expansion of the air parcel. The reduction in density and the corresponding force compared to the surrounding cooler air is what eventually allows the heated air to rise. Thus, while a significant result of heating is indeed the tendency to rise, the expansion itself plays a critical role in this process.