Which cloud type is thicker and darker than stratus, yet has a similar form?

• A. Observing the movement of clouds reveals wind speed
• B. Developed in an unstable environment aloft and can extend to vast altitude
• C. Formed from unstable air, often follows the diurnal cycle of solar heating
• D. Thicker and darker than, but similar in form to a stratus cloud

Answer: (D)

Think about how stratus and stratocumulus relate. Stratus clouds are a uniform, flat gray sheet close to the ground. If that sheet thickens and darkens but keeps a layered, sheet-like appearance with some texture or patches, the cloud type is stratocumulus. They sit low and are a bit more developed than pure stratus, often bringing light drizzle rather than heavy rain. This distinguishes them from clouds that are fully dark and rain-producing (like nimbostratus) or from tall, convective clouds that tower upward (like cumulonimbus). The description of being thicker and darker than stratus while maintaining a similar form matches stratocumulus.