88 lines
3.4 KiB
Markdown
88 lines
3.4 KiB
Markdown
# humidity
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Functions to compute relative humidity, absolute humidity, wet bulb
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temperature, and other values related to humidity of air, given
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partial data.
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## Purpose
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I'm using this code to explore human survivability given global warming. The following essays of mine are relevant:
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1. [The Everyone Dies Event Class](https://www.journeyman.cc/blog/posts-output/2021-11-15-the-everyone-dies-event-class/)
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2. [The 'everyone dies' event comes home](https://www.journeyman.cc/blog/posts-output/2026-07-15-Everyone-dies-UK/)
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3. [Extreme Heat](https://www.journeyman.cc/blog/posts-output/2026-07-31-Extreme-Heat/)
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4. [Analysis of 2026 heatwaves UK](https://www.journeyman.cc/blog/posts-output/2026-08-04-Analysis-of-2026-heatwaves-UK/)
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## Status
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Alpha-quality code. It more or less works but it isn't at all polished.
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## General architecture
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### The packet
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The 'packet', in the terminology of this library, is a map which has bindings
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for some of the following keywords:
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1. `:absolute-humidity`
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2. `:actual-vapour-pressure` *not yet implemented*
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1. `:dew-point` *not yet implemented*
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2. `:pressure-pascals`
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3. `:pressure-millibars`
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4. `:saturation-vapour-pressure`
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5. `:relative-humidity`
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6. `:temperature` *assumed to be celsius*
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7. `:temperature-celsius`
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8. `:temperature-kelvin`
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These keywords represent variables in the pressure equations, and they are all
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to a degree inter-related; so if you have (or can assume) some of them, you can
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compute others.
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Rather than having a tangle of functions all of which call one another, which seemed likely to result in horrible messes and potential infinite recursion, there is one central function, `humidity.core/resolution`, which takes a partial packet and repeatedly tries to compute the values for more variables until it can compute no more, and then returns the enhanced packet.
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Thus:
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```clojure
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humidity.core=> (use 'humidity.core :reload)
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nil
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humidity.core=> (resolution :relative-humidity 100 :temperature-celsius 35)
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{:relative-humidity 100, :temperature-celsius 35, :pressure-pascals 101325, :pressure-millibars 4053/4, :saturation-vapour-pressure 5622.488734516426, :temperature-kelvin 308.15, :absolute-humidity 3953.618101887827}
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```
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At present there are no checks to ensure that the packet makes sense.
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Associated with each variable there is a namespace which contains a function that takes a packet, and, provided that packet contains enough information to compute that variable, returns a numeric value, else `nil`.
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## Developing
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This is a fairly standard [leiningen](https://leiningen.org/) project. I anticipate that most Clojure developers will have leininen installed, even if they no longer use it much. Start a repl with
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```
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lein repl
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```
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and hook in your preferred editor as appropriate for that editor.
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## Testing
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Tests are reasonably complets but all could do with more examples, especially around the crucial 35° C wet bulb area and towards the extremities of normal weather range. If you are contributing additional code, I would appreciate it being accompanied by tests.
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I suggest running tests using
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```
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lein cloverage
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```
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As this gives not only pass/fail output, but also test coverage output.
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## Contributing
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Pull requests are welcomed, provided they do not contain AI generated code. I'm not going to waste time debugging Claude's mess, my own is bad enough.
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## License
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Copyright © 2026 Simon Brooke. Licensed under the GNU General Public License,
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version 2.0 or (at your option) any later version.
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