D'où viennent les nuages ?

D'où viennent les nuages ?

Where do clouds come from?

Title history
  • D'où viennent les nuages ? — observed on 20261019-0424 UTC (PSI archive)
🎙 David Louapre (ScienceEtonnante) 👥 1.5M 📅 January 5, 2018 ⏱ 16 min 👁 642K 📄 science communication 🧭 2026-10-19
Available in: English (current) Français

Keywords

cloudsevaporationcondensationKelvin effectRaoult effect

Summary

The video explores the formation of clouds, starting from the basic cycle of evaporation and condensation. It clarifies a common misconception: evaporation is not simply boiling at lower temperatures; it is governed by the partial pressure of water vapor relative to the liquid surface, as explained through phase diagrams. The video introduces the concept of relative humidity and explains why clouds cannot form spontaneously under typical atmospheric conditions due to the Kelvin effect, which requires high supersaturation for tiny droplets. The mystery is resolved by the presence of condensation nuclei, such as aerosols and salts, which lower the energy barrier for droplet formation. Additionally, the Raoult effect and surfactants, many of biological origin, further facilitate condensation. The explanation extends to ice clouds and the role of bacteria in snow cannons. Throughout, the video uses clear diagrams and analogies, making complex physical chemistry accessible. It also mentions the broader implications of clouds for climate modeling, emphasizing the importance of understanding these processes.

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Critical Evaluation

Value of the Information & Strength of the Argument

The video delivers high educational value by demystifying a common everyday phenomenon with precise scientific reasoning. The argumentation is well-structured: it raises a paradox (theoretical impossibility of clouds) and methodically resolves it using phase diagrams, the Kelvin effect, and nucleation theory. Each step builds on the previous, using intuitive analogies (pastis, champagne) without sacrificing accuracy. The presentation is engaging and logically coherent, leading the viewer from basic concepts to advanced physical chemistry.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high; the content aligns with established meteorology and physical chemistry. The video does not cite external sources directly but is accompanied by a blog post that provides further references (e.g., Köhler equations, cloud types). The title is faithful to the content, and the video stays on-topic throughout. The audience comments indicate strong appreciation for the clarity and depth, with no notable disagreements or corrections voiced.

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Title / Content Match

The title directly matches the content; the video answers the question 'Where do clouds come from?' with a focused, coherent explanation.

Quality & Reliability

9/10

The video provides a rigorous, step-by-step explanation of cloud formation, correctly addressing misconceptions about evaporation vs. boiling and incorporating key physical phenomena such as the Kelvin effect and Raoult's law. The author's background in physics and the accompanying blog post reinforce the reliability, though no formal citations are given in the video itself.

Key Moments

Cited Sources

  • Science étonnante blog — Official blog of the author with additional articles and resources.
  • Blog post accompanying this video — Detailed written explanation with links to further scientific resources.

Contribution & Novelties

This video brings a fresh perspective on cloud formation by rigorously dissecting the physics, correcting common misconceptions, and connecting multiple phenomena (Kelvin effect, Raoult effect, condensation nuclei) in a single coherent narrative. It goes beyond typical elementary explanations and offers a deeper understanding suitable for a curious audience.

Pour aller plus loin :

  • Köhler equation — The theoretical foundation describing the critical supersaturation for droplet activation, directly relevant to the video’s discussion of cloud condensation nuclei.
  • Cloud condensation nuclei — Essentiel pour comprendre comment les particules permettent la formation de gouttelettes.
  • Kelvin equation — Explains the effect of curvature on vapor pressure, central to the video’s explanation of why clouds need nuclei.

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Radar Profile

The radar profile shows consistently high scores across all dimensions (information quantity, quality, technical level, reliability), indicating a well-rounded and thorough scientific communication. The slight dip in technical level relative to the others suggests the content, while rigorous, is presented with clarity that limits unnecessary complexity.

Reliability 9/10

💬 Sur les 30 commentaires analysés, le climat est très positif : beaucoup de remerciements et des éloges pour la clarté des explications et la pédagogie.