Implement formula for LCL

lib/xmet/igra.py

@@ -78,6 +78,7 @@ class IGRAReader():
         sample.height_qa   = match['zflag']
         sample.temp        = parse_num(match['temp'], 0.1)
         sample.temp_qa     = match['tflag']
+        sample.humidity    = parse_num(match['rh'], 0.1)
         sample.dewpoint    = None
         sample.wind_dir    = parse_num(match['wdir'], 1.0)
         sample.wind_speed  = parse_num(match['wspd'], 0.1)

lib/xmet/sounding.py

@@ -4,8 +4,6 @@ import shapely
 LAPSE_RATE_DRY   = 9.8 / 1000 # degrees C per 1000m
 LAPSE_RATE_MOIST = 4.0 / 1000
 
-MIXING_RATIO_CONST = 621.97
-
 class SoundingSample():
     __slots__ = (
         'id', 'sounding_id', 'elapsed', 'pressure', 'pressure_qa',
@@ -47,6 +45,9 @@ class SoundingSample():
 
         return 621.97 * (es / (self.pressure - es))
 
+    def lcl(self) -> float:
+        return (self.temperature - self.dewpoint) / 8.0
+
     def is_saturated(self) -> bool:
         return self.humidity >= 100.0