Final answer:
At the circled arrow, warm air is rising due to its lower density compared to the surrounding cool air. This phenomenon is explained by Charles's Law and is essential in understanding buoyancy-driven convection in the Earth's atmosphere.
Step-by-step explanation:
At the point where the arrow is circled, warm air is rising. According to principles such as Charles's Law, as the temperature of air increases, its volume also increases but its density decreases, making it less dense than the cooler surrounding air. This results in a buoyant force that causes the air to rise due to its lower density. For example, this phenomenon is observed in hot air balloons where the heated air inside the balloon is less dense compared to the atmospheric air, which causes the balloon to ascend.
When considering the buoyant force acting on warm air in the context of atmospheric conditions, it's important to note that the movement of warm air rising and cool air sinking is a fundamental aspect of convection processes within the Earth's atmosphere. As highlighted in Figure 8.1, this buoyancy-driven convection is a key mechanism through which air circulates and weather patterns form.