code: def cloud_base(temp, hum):
      
      if temp is None or hum is None:
          return None
      dew_pt = dew_point(temp, hum)
      spread = float(temp) - dew_pt
      return spread * 125.0
docs: Calculate cumulus cloud base in metres, using formula from
      https://en.wikipedia.org/wiki/Cloud_base or
      https://de.wikipedia.org/wiki/Kondensationsniveau#Konvektionskondensationsniveau