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Height of base:

below 2000 m (6500 ft), even at ground, fog, mist (low-level clouds)


Grey, featureless;

Diffuse edges


World-wide; most common in coastal and mountain areas

Made of:

water droplets


None; possible light drizzle or graupel


Slow lifting of large layer


Nebulosus, fractus


Opacus, translucidus, undulatus

How to distinguish from

Cirrostratus (Cs)

Cs is higher and brighter; if translucidus, Cs forms halos or parahelia

Altostratus (As)

Hard to distinguish; As is higher than St; if translucidus sun appears less diffuse through St; sun has speckled appearance through As

Nimbostratus (Nb)

Nb has a ragged base and precipitation

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Stratus opacus

(Morris, November 2006)

Stratus fractus opacus

(Morris, November 2006)

Stratus nebulosus translucidus

(Morris, January 2007)

Stratus nebulosus translucidus

Morris, March 07

Stratus with virga

Morris, May07

Orographic stratus opacus,

evaporation fog on lake

Hebgen Lake, Mo, July06







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Last modified: 1/14/2008

Maintained by Sylke Boyd


The views and opinions expressed in this page are strictly those of the page author. The contents of this page have not been reviewed or approved by the University of Minnesota.