What defines a thunderstorm?

A thunderstorm is specifically defined as a local storm that is produced by a cumulonimbus cloud. These clouds are towering, vertically-developed clouds that are capable of producing significant weather phenomena, including heavy rainfall, strong winds, lightning, and sometimes hail. Cumulonimbus clouds are associated with intense convective activity which is essential for the development of thunderstorms.

The formation of a thunderstorm requires rising warm, moist air, which cools and condenses as it ascends, leading to the development of cumulonimbus clouds. This process results in the instability and energy necessary for thunderstorm activity, including the generation of thunder and lightning as the cloud particles collide and create electrical charges.

Understanding the characteristics of cumulonimbus clouds helps to clarify why it is the correct answer, as these clouds are not merely involved in rainfall or steady weather events but are the key atmospheric feature necessary for thunderstorms. Other options may refer to different types of weather phenomena that do not meet the criteria for defining a thunderstorm. For instance, nimbostratus clouds typically produce prolonged, gentle rain rather than the intense, short-lived storms characteristic of thunderstorms. Similarly, global storms or storms characterized only by steady rain fall outside the specific definition associated with thunderstorms.