Peter Mander, author and editor of CarnotCycle blog. Physical chemist by training, with a particular interest in thermodynamics.

He is the originator of novel formulas (2012 and 2020) for computing absolute humidity, defined as water vapor density in g/m^3, from temperature and relative humidity. Published applications of the 2012 formula range from mapping urban climate patterns across the US and analyzing the seasonal dynamics of influenza in Australia to calibrating hurricane-monitoring satellites and powering microcontroller software for humidity monitoring and management.

  1. Ethan Mitchell says:

    Thanks so much!


  2. Peter Mander says:

    Hi Ethan, thank you for the enquiry regarding William Thomson’s hunt for Sadi Carnot’s original publication. I think the anecdote started with Thomson himself in an article he wrote for the Fortnightly Review in March 1892 [ref 1], the year he became Lord Kelvin. The story found its way into the 1910 biography of His Lordship by Sylvanus Thompson (not related, Thompson differently spelled) in the chapter dealing with Thomson’s postgraduate activities in Paris [ref 2]. It would seem that Thomson eventually got hold of Carnot’s original text from Lewis Gordon [ref 3], one of his fellow professors at Glasgow University, who apparently was studying in Paris at or around the time Carnot produced his masterwork. Hope this helps. Regards Peter
    [1] https://babel.hathitrust.org/cgi/pt?id=coo.31924066515267&view=1up&seq=329&skin=2021
    [2] https://archive.org/details/b31360403_0001/page/132/mode/2up
    [3] https://en.wikipedia.org/wiki/Lewis_Gordon_(civil_engineer)


  3. Ethan Mitchell says:

    Peter Mander, I am an amateur historian and I’m trying to track down an anecdote that I think you might be able to help me with. The story goes like this: William Thompson, Lord Kelvin, hears about Carnot’s book from Clapeyron’s article, and realizes he needs to read it. It’s impossible to find, so he goes to Paris to hit the booksellers, but arrives there during the “June Days” uprising, and is basically knocking on doors looking for a book in the middle of street fighting. This checks out time-wise: it appears to me that Kelvin hadn’t read Carnot in early 1848 and by the end of the year he had. But I have beaten my head against a wall trying to corroborate this story, so I’d love some assistance, even if it’s “go home, dude”.



  4. Timoer says:

    I do not know why I discovered this collection of blogs so late, but they are great. As a physical chemist I truly enjoy reading them. Thanks!


  5. Peter Mander says:

    Hi Blaine and thank you for the suggestion of a Search widget which I have now added.


  6. Blaine says:

    Thank you for this fascinating collection on thermodynamics. I’m not a mathematician but have had a life long interest in nonequilibrium thermo and the work of Prigogine and others mostly from a philosophy of science perspective. Is it possible to search your articles for key words?


  7. William Nicholson says:

    Hey Peter, thanks for the publicity on William Nicholson (1753-1815). If readers are interested, you can find out more at http://www.nicholsonsjournal.com. And I have a Twitter account @Wm_Nicholson


  8. flowcoef says:

    W00t. Unfortunately my skills in thermo and history are not at the level that lets me intelligently comment on individual posts. Still, I love your work here.


  9. Hi Peter,

    Thank you so much for visiting my blog and liking so many of my posts! I love physical chemistry, and I really like your blog! I aspire to use machine learning to study physical chemistry in novel ways, and The Chemical Statistician allows me to lay the foundation of my thoughts to build that dream.

    I look forward to reading more of your posts and learning more from you!




  10. Stacey says:

    Your formula relative humidity to absolute humidity and the following explanation were helpful to me. Thanks!


  11. elkement says:

    Your blog is extremely interesting for me – I am physicist and engineer (working with heat pumps), and history of science is a hobby of mine. I will follow your blog.


  12. Thank you for “liking” my article, “The Thermodynamics of an Intelligent Living Universe”. I appreciated your description of “assisted entropy”, as civilization’s conversion of rare (and not-so-rare) elements into irretrievable waste has become the bane of terrestrial life, and this form of entropy is often ignored in discussions about sustainability through “advances” in technology. Jeremy Rifkin dealt with this in his seminal 1980 book Entropy, in which he described civilization as “creating islands of order amidst seas of disorder”.


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