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The LibraryODERSA publishing house
An ODERSA resource · Knowledge programmeA book only goes online once it is whole and read by someone else.

Chapter 16 of 17 · Water and the Weather

Sources

Every page opened in order to write this volume, with its address and the date of consultation, plus what was set aside and why.

What this chapter commits the house to

Every fact in this volume goes back to an entry in this chapter. That is not a form of words: it is a rule of manufacture, and it was held to during the writing, fact by fact. A fact the house could not attach to an open source it had read did not go into the volume; it came out of it, or it never went in.

All the pages listed here were opened and read, on the dates given, and not quoted from memory. That is what makes disagreement possible: if a sentence in this volume seems wrong to you, you can open the same page, at the same address, and look. A bibliography that does not allow that serves only to look serious.

The sources were chosen on a simple order of priority. A first-hand source beats three commentaries: a national weather service on wind, the organisation that maintains the international classification on clouds, the public water information service on groundwater, the public report on the state of the environment on abstraction. Where an official source gave a figure, it is its figure that is written, with its date.

One remark on method, finally, because it has consequences for a reader. Official figures age. The fresh water abstraction figures are those of a precise year, the climate reference period changes once a decade, and schemes are reformed. Every figure in this volume therefore carries its year, and the review interval of the volume is written in its colophon. A figure without a date is a piece of information that cannot be checked.

Meteorology, clouds and climate

The public pages of Météo-France and of the World Meteorological Organization. They carry the formation of clouds, the definition of precipitation, humidity, the measurement of temperature and of wind, the making of a forecast, the weather warning scheme and the climatological normals. The conditions of reuse of these pages belong to their publishers: this volume cites them and does not reproduce them.

  1. Le cycle de l'eau: the stages of the cycle and how they follow on from one another, page dated 4 August 2026Météo-France · consulted on August 9, 2026meteofrance.com/comprendre-la-meteo/actualites-et-dossiers/le-cycle-de-leau
  2. Les précipitations, pluie, neige, grêle: definitions, diameter thresholds, the equivalence of the millimetre of rain, the radar networkMétéo-France · consulted on August 9, 2026meteofrance.com/actualites-et-dossiers/comprendre-la-meteo/les-precipitations-pluie-neige-grele
  3. Comment se forme un nuage: condensation, saturation, and the four mechanisms of coolingMétéo-France · consulted on August 9, 2026meteofrance.com/meteo-a-z/comment-se-forme-un-nuage
  4. Comment se forme un nuage, feature article: the six changes of state named in a single sentence, the division between those that demand energy and those that release it, and the sentence about expansion quoted in the chapter on clouds: a body of air that gains height sees its pressure fall, which cools itMétéo-France · consulted on August 9, 2026meteofrance.com/comprendre-la-meteo/nuages/comment-se-forme-un-nuage
  5. Les nuages: composition, classification into ten genera, dimensions of the cumulonimbus, definition of fogMétéo-France · consulted on August 9, 2026meteofrance.com/comprendre-la-meteo/nuages
  6. Qu'est-ce que l'humidité: relative humidity, the share of water vapour in the air, the composition of the atmosphere, the link between temperature and quantity of vapour, and the observed floor of humidity in mainland FranceMétéo-France · consulted on August 9, 2026meteofrance.com/actualites/quest-ce-que-lhumidite
  7. Qu'est-ce que la température: measurement 1.5 metres above the ground, the white louvred screen, and the standards of the World Meteorological OrganizationMétéo-France · consulted on August 9, 2026meteofrance.com/comprendre-la-meteo/temperatures/quest-ce-que-la-temperature
  8. Qu'est-ce que le vent: definition, origin in differences of pressure, units of speed, instantaneous wind and mean windMétéo-France · consulted on August 9, 2026meteofrance.com/comprendre-la-meteo/le-vent/quest-ce-que-le-vent
  9. Les grandes étapes de la prévision: observation, the ARPEGE and AROME models, the Belenos and Taranis supercomputersMétéo-France · consulted on August 9, 2026meteofrance.com/meteo-a-z/les-grandes-etapes-de-la-prevision
  10. Qu'est-ce que la Vigilance météorologique: the purpose of the scheme, the four colours, the events followed, the rate of updatingMétéo-France · consulted on August 9, 2026meteofrance.com/vigilance-et-securite/quest-ce-que-la-vigilance-meteorologique
  11. De nouvelles normales pour qualifier le climat en France: calculation over thirty years, the move from 1981-2010 to 1991-2020 on 28 June 2022Météo-France · consulted on August 9, 2026meteofrance.com/actualites/de-nouvelles-normales-pour-qualifier-le-climat-en-france
  12. Étages des nuages: the vertical division of the troposphere, the table of heights by region, and the spread of the ten genera over the three levelsInternational Cloud Atlas, World Meteorological Organization · consulted on August 9, 2026cloudatlas.wmo.int/fr/some-useful-concepts-levels.html
  13. Genres de nuages: the ten genera of the international classificationInternational Cloud Atlas, World Meteorological Organization · consulted on August 9, 2026cloudatlas.wmo.int/fr/clouds-genera.html

Water, groundwater and networks

The public water information service, two water agencies that publish teaching material freely available to all, and the public report on the state of the environment for the abstraction figures. The conditions of reuse of these pages belong to their publishers: this volume cites them and does not reproduce them.

  1. Les eaux souterraines: infiltration, aquifer, groundwater, impermeable bedrock, and the place of the water table in drinking water supplyEaufrance, service public d'information sur l'eau · consulted on August 9, 2026www.eaufrance.fr/les-eaux-souterraines
  2. Bassin versant: the technical definition, the everyday definition, and the watershedEaufrance, glossaire · consulted on August 9, 2026www.eaufrance.fr/glossaire/bassin-versant
  3. L'eau potable et l'assainissement: the origin of raw water, making it drinkable, and the fact that drinking water never comes from wastewater treatment plantsEaufrance · consulted on August 9, 2026www.eaufrance.fr/leau-potable-et-lassainissement
  4. Le petit cycle de l'eau: from the resource to the tap and from the tap to the environment, public sewerage and on-site sanitationAgence de l'eau Seine-Normandie · consulted on August 9, 2026www.eau-seine-normandie.fr/les-cycles-de-l-eau/le-petit-cycle-de-l-eau
  5. Le petit cycle de l'eau: the five stages named by the agency, from pumping to the treatment of waste water, and the distinction between clean water and drinking water. The division into six stages adopted by this volume is its own: it separates the collection of waste water from its treatment, because they are two different worksAgence de l'eau Artois-Picardie, dossiers thématiques · consulted on August 9, 2026www.eau-artois-picardie.fr/education-leau-dossiers-thematiques/le-petit-cycle-de-leau
  6. Comment est utilisée l'eau douce en France: volume abstracted in 2022, breakdown by use, share of surface water and of groundwater, share actually consumedNotre-environnement, rapport public sur l'état de l'environnement · consulted on August 9, 2026www.notre-environnement.gouv.fr/themes/economie/l-utilisation-des-ressources-naturelles-ressources/article/comment-est-utilisee-l-eau-douce-en-france
  7. Les rivières: what feeds a watercourse from the source to the outlet, and the network of stations where water levels and discharges are recordedEaufrance, service public d'information sur l'eau · consulted on August 9, 2026www.eaufrance.fr/les-rivieres

The school structures cited in the appendix

The text that sets the science and technology syllabuses of which this volume covers some of the notions. It is cited at its official address, that of the public legal information service, and not at a commentary. Its title is given here ABRIDGED, and that is worth saying rather than leaving it to be discovered: the full title names the cycles of education concerned, whereas this house writes no national schooling marker into its volumes, because it publishes in seven languages and because such a marker would be wrong for six of them on the day it is written. The date, the NOR number, the number of the Journal officiel and the address identify the text unambiguously, and the whole title can be read at the address given.

  1. Arrêté du 5 juin 2026 fixant les programmes d'enseignement de sciences et technologie, NOR MENE2611650A, published in the Journal officiel no. 0133 of 9 June 2026, title abridged hereLégifrance, service public de la diffusion du droit · consulted on August 9, 2026www.legifrance.gouv.fr/jorf/id/JORFTEXT000054218988
  2. Connaître l'enseignement fondamental: its two levels, the age of entry into the first year, and the length of compulsory schoolingFédération Wallonie-Bruxelles, portail officiel · consulted on August 9, 2026www.federation-wallonie-bruxelles.be/demarche/1218-connaitre-lenseignement-fondamental-en-federation-wallonie-bruxelles
  3. Structure du Plan d'études romand: the eleven years of compulsory schooling and their spread over three multi-year cyclesConférence intercantonale de l'instruction publique de la Suisse romande et du Tessin · consulted on August 9, 2026portail.ciip.ch/per/pages/244
  4. La structure du programme: the three cycles of two years and the age of admission to the first yearCentre de services scolaire de Montréal · consulted on August 9, 2026www.cssdm.gouv.qc.ca/prescolaire-primaire/programme-primaire

What guided the form of this volume

A manual is not made out of facts alone: its form is decided too, and it is decided by looking at what the reference open textbooks do. These pages were opened for that, before the plan was written.

  1. A section of an open textbook in situ: learning objectives at the top, opened by action verbs, and named boxes inside the courseOpenStax, Concepts of Biology, section 1.1 · consulted on August 9, 2026openstax.org/books/concepts-biology/pages/1-1-themes-and-concepts-of-biology
  2. The publisher's own description of its teaching apparatus: examples that pose a question, unfold a solution, then hand back to the readerOpenStax, Chemistry 2e, preface · consulted on August 9, 2026openstax.org/books/chemistry-2e/pages/preface
  3. The education area of a national weather service: sections, teaching sheets, animations and activitiesMétéo-France, Éducation · consulted on August 9, 2026meteofrance.com/education/comprendre-la-meteo

What was set aside, and why

A volume that had set nothing aside would have read nothing. Here are the decisions taken during the research, with their reason, because they throw light on what the volume contains.

The figures for the distribution of water on the planet were set aside. The proportions of salt water and fresh water, and the share locked up in ice, circulate everywhere with values that are close but not identical and with sources that are often second-hand. Rather than write a percentage the house could not have attached to a first-hand source opened on the day of writing, the volume keeps to what a national service writes in black and white: water covers nearly three quarters of the surface of the globe. The rest is worked out from mechanisms, not from percentages.

The mechanisms of the atmosphere at the scale of the globe were set aside from the plan. Circulation cells, high-altitude jets and the force linked to the rotation of the Earth explain a great deal, and they call for tools this volume does not assume are already known. Mentioning them without dealing with them would have given names without understanding, which is exactly what this volume seeks to avoid.

Experiments using a flame were all set aside, including the most classic one in the field, the one that makes a cloud by introducing the smoke of a match into a bottle in order to supply condensation nuclei. The reason is the house rule: an experiment in this volume must be able to be carried out in somebody's home, with an adult, without equipment and without risk. The version with the jar, hot water and ice cubes obtains the same visible result without fire.

What to do in the event of a dangerous phenomenon was set aside, and that is the firmest decision in the volume. The house teaches how a field works; it never prescribes an action whose failure would leave somebody in difficulty. What is published here is how the warning scheme works; what should be done is published with the map, at the moment the danger exists, and that is not copied into a book.

Thresholds the sources do not give were set aside, even where they circulate everywhere. The clearest case is that of ice pellets: hail is defined by a diameter greater than five millimetres, and it would be convenient to deduce that ice pellets are what falls below that threshold. None of the open sources says so, and this volume therefore does not put those words in their mouth. It names ice pellets, it describes them, and it points out that their diameter is not fixed at the source. A deduced threshold that looks like a definition is exactly the kind of mistake a manual passes on for twenty years.

Finally, commentaries and summary websites were systematically replaced by the source they were commenting on, whenever that source was freely available. The regulatory text is cited at the public legal information service rather than at a summary; the classification of clouds is cited at the international atlas rather than at a page that repeats it. And the rule was pushed all the way inside the quotation marks themselves: a sentence between quotation marks in this volume is found word for word on the page indicated, punctuation included. Where the exact wording could not be found again, the quotation marks were removed and the sentence rewritten as an explanation by the house, under its own responsibility. In this English edition, those quoted sentences are given in the house's own translation: what is found word for word at the address indicated is the French sentence they render.

A mistake in this volume is reported to labibliotheque@odersa.org, giving the chapter and the exact sentence. A precise report is dealt with faster than a report saying that there is a mistake somewhere. ODERSA corrects the text, redates the volume, and says what has changed.