Clouds - Twelve Classifications 1923

To the mariner and to the ocean traveler as well, clouds mean much and naturally they furnish a frequent topic of conversation during the average sea voyage. The old physical geographies divided clouds into four kinds, but the Weather Bureau of the U. S. Department of Agriculture make no fewer than twelve classifications. These are as follows:

  1. Cirrus: Isolated feathery clouds of fine, fibrous texture, generally white, frequently arranged in bands, spreading over a part of the sky. The cirrus is often closely connected with depressions of the barometer and upon its appearance weather observers base many of their forecasts.
  2. Cirro-stratus: A fine, whitish veil giving a milky appearance to the sky, though sometimes exhibiting tangled fibres. The veil often produces halos around the sun and moon.
  3. Cirro-cumulus: Fleecy, small white balls and wisps with very faint shadows or without, arranged in groups or rows.
  4. Alto-cumulus: Large whitish or grayish balls with shaded portions, grouped in flocks or rows, frequently with the edges meeting. Often arranged in lines in one or two directions.
  5. Alto-stratus: A thick veil, gray or bluish, exhibiting a brighter portion in the vicinity of the sun or moon.
  6. Strato-cumulus: Large rolls or balls of dark clouds, frequently covering the whole sky in winter. Often the blue sky appears in breaks through it. This is not classed as a rain cloud.
  7. Nimbus: Dense, dark masses with ragged edges, from which generally a continuous rain or snow is falling. if the mass is torn into small patches, 'or if low fragments float much below a great nimbus, sailors call such a cloud a "scud."
  8. Cumulus: In appearance great masses of snow white wool, with dome-like summits and flat bases.
  9. Cumuto-nimbus: This is the thunder or shower cloud; heavy masses, rising like towers or mountains, usually surrounded at the top by a screen of fibrous texture and by nimbus-like banks at the base. From the last usually falls rain, or snow, hail or sleet.
  10. Stratus: Layers, uniform in shape and appearance, resembling a fog, but not resting on the ground.
  11. Fracto-stratus: Stratus is so called when it is broken into irregular shreds by the wind or by summits of mountains.
  12. Fracto-cumulus: Cumulus broken up by strong winds, when the detached portions undergo continual changes.
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