Final answer:
The cumulus stage of a thunderstorm is characterized by a continuous updraft, which is essential for the cloud's vertical growth and can lead to the development of a thunderstorm.
Step-by-step explanation:
The feature normally associated with the cumulus stage of a thunderstorm is a continuous updraft. Cumulus clouds indicate the initial phase of thunderstorm development, resulting from air that rises due to convection. Convection is the process where warmer, less dense air ascends, while cooler, denser air sinks. This upward movement is driven by a positive feedback mechanism, where the warmth provided by the rising moisture-rich air causes more water vapor to rise and the cloud to grow. This process is clearly visible as the cumulus clouds become more substantial. These clouds can eventually develop into mature thunderstorms if the conditions are favorable, with sufficient moisture and instability in the atmosphere.
Different stages of a thunderstorm exhibit distinct features. While the cumulus stage is known for its continuous updraft, other stages of a thunderstorm may show characteristics such as frequent lightning, roll clouds, or other severe weather phenomena. However, it's the continuous updraft that typifies the cumulus stage and is crucial for the vertical growth that can lead to the subsequent development of a thunderstorm.