Stratus clouds are low altitude gray clouds that make a flat base. The name comes from the Latin word stratus, which means to "stretch" or "extend." You can see stratus clouds as thick cloud blankets near the sea. They are sometimes called "high fogs".
Light rain and drizzle often fall from stratus clouds. When rain falls from stratus clouds they are mostly called nimbostratus  The name derives from the Latin word nimbus = rain, and stratus = spread out.
- Wonders of Creation, The Weather Book, p. 23