What characteristic defines stratus clouds?

Stratus clouds are primarily characterized by their flat, uniform appearance, resembling a thick blanket covering the sky. They typically present in a light grey color and manifest at lower altitudes. This characteristic often leads them to obscure sunlight, giving the environment a subdued, overcast look. Stratus clouds can also bring light precipitation, such as drizzle, but they are mainly known for their expansive, horizontal formation that contrasts with other cloud types that are more vertically developed.

The other options describe different types of clouds that have distinct characteristics. Fluffy and white clouds are typically cumulus clouds, known for their puffy appearance and usually found at higher altitudes. Thin and wispy clouds refer to cirrus clouds, which are high-altitude clouds made of ice crystals, often seen on clear, sunny days. Dark and stormy clouds are associated with nimbus clouds or cumulonimbus clouds, which are known for producing heavy rain and storms. Understanding the specific characteristics of these clouds helps in identifying weather patterns and conditions.