Stratus is a generally grey, featureless cloud layer with a fairly uniform base, which may give drizzle, snow or snow grains. It forms in stable, moist air lifted or mixed gently, and often appears as hill and coastal cloud. When its base sinks to ground level it is, by definition, simply fog. The sun's outline is usually visible through it, but stratus produces no halos except, perhaps, in extreme cold.
Worth knowing
Stratus at ground level is simply fog - the only difference is your vantage point!
San Francisco's famous fog is actually stratus cloud rolling in from the Pacific Ocean.
These clouds rarely produce more than 0.25mm of precipitation per hour.
Mountain peaks often 'wear' stratus clouds like a cap, called a 'tablecloth' effect.
Note
Still unsure it's the same cloud? Our app, Cloud Point— on iOS and Android — reads a photo and returns the likely type with altitude, useful when a formation is fading faster than you can look it up.
