---
source: https://iinventedlight.com/library/notes/cloud-types.md
title: "Cloud types: cirrus, cumulus, stratus and nimbus"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, Clouds, US government work, public domain; NOAA, The Four Core Types of Clouds, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: weather and atmosphere"
tags: science, weather, clouds
sources:
  - id: S1
    title: "Clouds"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/clouds
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "The Four Core Types of Clouds"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/clouds/four-core-types-of-clouds
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Cloud types: cirrus, cumulus, stratus and nimbus

## 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).