What type of cloud is characterized by patches, sheets, or layers that are grey or whitish and resemble large pebbles?

The cloud type described in the question is stratocumulus. Stratocumulus clouds are typically found in the lower to mid-level part of the atmosphere and are characterized by their patchy or layered appearance, appearing grey or whitish. Their formation often results in a lumpy or rolling texture, resembling large pebbles, which is a distinctive feature of these clouds. The sheets or layers can cover the sky partially or completely, but they tend not to produce significant precipitation, making them a common sight on overcast or partly cloudy days.

Understanding the characteristics of stratocumulus is important in weather observation and forecasting, as they may indicate stable atmospheric conditions. This knowledge helps pilots and meteorologists interpret weather patterns effectively. The other cloud types, such as cumulonimbus and nimbostratus, have different characteristics and are associated with varying weather conditions, which makes them distinctly identifiable from stratocumulus clouds.