Clouding the Looking-Glass

Altocumulus (Ac) - the name derives from the latin words altus = high and cumulus = mass or heap. Altocumulus is a member of the ten fundamental cloud types (or cloud genera). It is a middle-level cloud, thus they usually form between 2 to 7 kilometers (6,500 to 22,000 ft).

Altocumulus cloud usually occur as a layer or patch of more or less separate cloudlets in the form of heaps, rolls, billows or pancakes.

Altocumulus clouds chiefly consist of super-cooled water droplets of minus 10C, but ice crystals are often present.

Stratus clouds are a genus of low-level cloud characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds that are formed by rising thermals. 

More specifically, the term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color from dark gray to nearly white.

Some call these clouds "high fog" for the fog-like cloud.

While light rain may fall, this cloud does not indicate much meteorological activity.

Cirrus (cloud classification symbol: Ci) is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word cirrus meaning a ringlet or curling lock of hair. The strands of cloud sometimes appear in tufts of a distinctive form referred to by the common name of "mares' tails".

Cirrus generally appears white or light gray in color. It forms when water vapor undergoes deposition at altitudes above 5,000 m (16,500 ft) in temperate regions and above 6,100 m (20,000 ft) in tropical regions. It also forms from the outflow of tropical cyclones or the anvils of cumulonimbus cloud. Since cirrus clouds arrive in advance of the frontal system or tropical cyclone, it indicates that weather conditions may soon deteriorate. While it indicates the arrival of precipitation (rain), cirrus clouds per se produce only fall streaks (falling ice crystals that evaporate before landing on the ground).

Jet stream-powered cirrus can grow long enough to stretch across continents while remaining only a few kilometers deep.

 

A nimbus cloud is a cloud that produces precipitation. Usually the precipitation reaches the ground as rain, hail, snow, or sleet. Falling precipitation may evaporate as virga. Rain comes out of nimbus clouds and this is called precipitation.
Since nimbus clouds are dense with water, they appear darker than other clouds. Nimbus clouds are formed at low altitudes and are typically spread uniformly across the sky.