# humidity

Functions to compute relative humidity, absolute humidity, wet bulb 
temperature, and other values related to humidity of air, given 
partial data.

## Purpose

I'm using this code to explore human survivability given global warming. The following essays of mine are relevant:

1. [The Everyone Dies Event Class](https://www.journeyman.cc/blog/posts-output/2021-11-15-the-everyone-dies-event-class/)
2. [The 'everyone dies' event comes home](https://www.journeyman.cc/blog/posts-output/2026-07-15-Everyone-dies-UK/)
3. [Extreme Heat](https://www.journeyman.cc/blog/posts-output/2026-07-31-Extreme-Heat/)
4. [Analysis of 2026 heatwaves UK](https://www.journeyman.cc/blog/posts-output/2026-08-04-Analysis-of-2026-heatwaves-UK/)


## Status


Alpha-quality code. It more or less works but it isn't at all polished.

## General architecture

### The packet

The 'packet', in the terminology of this library, is a map which has bindings
for some of the following keywords:

1. `:absolute-humidity`
2. `:actual-vapour-pressure` *not yet implemented*
1. `:dew-point` *not yet implemented*
2. `:pressure-pascals` 
3. `:pressure-millibars` 
4. `:saturation-vapour-pressure`
5. `:relative-humidity`
6. `:temperature` *assumed to be celsius*
7. `:temperature-celsius` 
8. `:temperature-kelvin` 

These keywords represent variables in the pressure equations, and they are all
to a degree inter-related; so if you have (or can assume) some of them, you can
compute others.

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.

Thus:

```clojure
humidity.core=> (use 'humidity.core :reload)
nil
humidity.core=> (resolution :relative-humidity 100 :temperature-celsius 35)
{: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}
```

At present there are no checks to ensure that the packet makes sense.

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`.

## Developing

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

```
lein repl
```

and hook in your preferred editor as appropriate for that editor.

## Testing

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.

I suggest running tests using

```
lein cloverage
```

As this gives not only pass/fail output, but also test coverage output.

## Contributing

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.

## License

Copyright © 2026 Simon Brooke. Licensed under the GNU General Public License,
version 2.0 or (at your option) any later version.