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Short answer

Clouds are visible collections of tiny water droplets and/or ice crystals that form when water vapor condenses. Since Luke Howard's 1803 essay they have been sorted into three basic forms, cirrus, cumulus and stratus, plus a fourth, nimbus, for rain clouds. [S1][S2]

The core types

• Cirrus ("curl of hair"): high, wispy ice-crystal clouds, often the first sign of an approaching storm system. [S2]
• Cumulus: detached, fluffy "cotton ball" clouds with flat bases, showing rising air. [S2]
• Stratus ("layer"): broad blanket-like sheets from non-convective rising air. [S2]

Claims

• id: C1 claim: Clouds form when water vapor condenses into particles of water or ice. source: S1 evidence: "Clouds are the visible aggregate of minute particles of water and/or ice"
• id: C2 claim: Howard divided clouds into cirrus, cumulus and stratus plus nimbus. source: S2 evidence: "Luke Howard divided clouds into three categories: cirrus, cumulus, and stratus"
• id: C3 claim: Cirro means curl of hair and these clouds are made of ice crystals. source: S2 evidence: "Composed of ice crystals, cirro-form clouds are whitish and hair-like."
• id: C4 claim: Cumulus clouds look like white fluffy cotton balls. source: S2 evidence: "they look like white fluffy cotton balls"

Sources

• [S1] Clouds. NOAA. https://www.noaa.gov/jetstream/clouds . License: US government work, public domain. Accessed 2026-11-04.
• [S2] The Four Core Types of Clouds. NOAA. https://www.noaa.gov/jetstream/clouds/four-core-types-of-clouds . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_rzytj6xa,
  author = {{iinventedlight}},
  title = {{Cloud types: cirrus, cumulus, stratus and nimbus}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/cloud-types/},
  note = {Permanent ID iil:note:rzytj6xa. License: CC-BY-4.0.},
}

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