What type of cloud is known for causing rapid changes in sky conditions due to its showery nature?

Cumulus clouds are known for their showery nature and potential to cause rapid changes in sky conditions. These clouds typically form through convection, which means they can develop quickly, leading to localized areas of precipitation. As they build vertically, cumulus clouds can evolve into larger, more complex systems, resulting in sudden weather changes such as showers or thunderstorms. This feature distinguishes them from clouds like stratus, which are generally more uniform and stable, and nimbostratus, which are associated with steady, prolonged rain rather than quick changes. Cirrus clouds, being high-altitude and thin, do not contribute to significant precipitation at the surface. Therefore, cumulus clouds are the most associated with abrupt weather shifts, making them the correct answer in this context.