I have not yet got the overall architecture right, but the functions are

beginning to work.

resources/katzenberger.txt

@@ -0,0 +1,49 @@
+# I'm guessing this is Python
+
+# Saturated water vapor pressure in hPa, Magnus Formula
+# Parameters from Sonntag1990, for −45 °C ≤ T ≤ 60 °C (error ±0.35 °C).
+def saturatedVaporPressureMagnusSonntag1990(temperatureCelsius):
+    a = 6.112
+    b = 17.62
+    c = 243.12
+
+    saturatedVaporPressure = a * math.exp((b * temperatureCelsius) / (c + temperatureCelsius))
+    return saturatedVaporPressure
+
+
+# Saturated water vapor pressure in hPa, Tetens Formula
+def saturatedVaporPressureTetens(temperatureCelsius):
+    a = 6.1078
+    b = 17.27
+    c = 237.3
+
+    saturatedVaporPressure = a * math.exp((b * temperatureCelsius) / (c + temperatureCelsius))
+    return saturatedVaporPressure
+
+
+# Saturated water vapor pressure in hPa, Buck 1996 Formula
+def saturatedVaporPressureBuck1996(temperatureCelsius):
+    if temperatureCelsius < 0:
+        return 6.1115 * math.exp(
+            (23.06 - temperatureCelsius / 333.7) * (temperatureCelsius / (279.82 + temperatureCelsius)))
+    else:
+        return 6.1121 * math.exp(
+            (18.678 - temperatureCelsius / 234.5) * (temperatureCelsius / (257.14 + temperatureCelsius)))
+
+
+# Actual water vapor pressure in hPa
+def vaporPressure(relativeHumidity, temperatureCelsius):
+    vaporPressure = relativeHumidity / 100.0 * saturatedVaporPressureBuck1996(temperatureCelsius)
+    return vaporPressure
+
+
+# Absolute humidity in g/m³
+def absoluteHumidity(relativeHumidity, temperatureCelsius):
+    molarMassOfWaterVapor = 18.01528
+    universalGasConstant = 8314.46261815324
+    zeroCelsiusInKelvin = 273.15
+
+    absoluteHumidity = 10 ** 5 * molarMassOfWaterVapor / universalGasConstant * vaporPressure(relativeHumidity,
+                                                                                              temperatureCelsius) / (
+                               temperatureCelsius + zeroCelsiusInKelvin)
+    return absoluteHumidity