From 7c9af22d5106b84b202bf38b324d7dbfde876d7e Mon Sep 17 00:00:00 2001
From: XANTRONIX Industrial <xan@xantronix.com>
Date: Fri, 7 Mar 2025 13:58:58 -0500
Subject: [PATCH] Implement mixing_ratio_temp()
---
lib/xmet/thermo.py | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/lib/xmet/thermo.py b/lib/xmet/thermo.py
index b48bbe9..2631782 100644
--- a/lib/xmet/thermo.py
+++ b/lib/xmet/thermo.py
@@ -1,3 +1,5 @@
+import math
+
from typing import Callable
LAPSE_RATE_DRY = 9.8 / 1000 # degrees C per km
@@ -10,6 +12,9 @@ PRESSURE_STEP = 50
def kelvin(c: float) -> float:
return 273.15 + c
+def celsius(k: float) -> float:
+ return k - 273.15
+
def vapor_pressure(dewpoint: float) -> float:
"""
Return the pressure, in millibar, of vapor in a parcel of a given
@@ -42,6 +47,23 @@ def saturated_mixing_ratio(temp: float, pressure: float) -> float:
return (0.62197 * es) / (pressure - es)
+def mixing_ratio_temp(ratio: float, pressure: float) -> float:
+ """
+ Return the temperature, in degrees celsius, of a given mixing ratio at a
+ specified pressure, in millibar.
+ """
+ c1 = 0.0498646455
+ c2 = 2.4082965
+ c3 = 7.07475
+ c4 = 38.9114
+ c5 = 0.0915
+ c6 = 1.2035
+
+ x = math.log10(ratio * pressure / (622.0 + ratio))
+
+ return celsius(math.pow(10.0, ((c1 * x) + c2)) - c3 + \
+ (c4 * math.pow((math.pow(10, (c5 * x)) - c6), 2)))
+
def lcl(temp: float, dewpoint: float) -> float:
"""
Return the height, in meters, at which a parcel of the given temperature