lib/xmet/skew_t.py

@@ -4,8 +4,6 @@ import cairo
 from typing import Callable
 
 from xmet.sounding import Sounding
-from xmet.thermo   import pressure_height, lapse, \
-                          LAPSE_RATE_MOIST, LAPSE_RATE_DRY
 
 PRESSURE_MAX  = 1050 # millibar
 PRESSURE_MIN  =  100
@@ -103,47 +101,6 @@ class SkewTGraph():
 
         cr.restore()
 
-    def draw_adiabat(self,
-                     cr: cairo.Context,
-                     x: float,
-                     y: float,
-                     start_temp: float,
-                     start_pressure: float,
-                     lapse_rate: float):
-        start_height = pressure_height(start_pressure)
-        sx_last = None
-        sy_last = None
-
-        pressure = start_pressure
-
-        while pressure >= PRESSURE_MIN:
-            height   = pressure_height(pressure)
-            temp_cur = lapse(start_temp, lapse_rate, height - start_height)
-
-            sx, sy = self.sample_to_screen(temp_cur, pressure)
-
-            if sx_last is not None:
-                cr.move_to(x + sx, y + sy)
-                cr.line_to(x + sx_last, y + sy_last)
-                cr.stroke()
-
-            sx_last = sx
-            sy_last = sy
-
-            pressure -= 10.0
-
-    def draw_adiabats(self,
-                      cr: cairo.Context,
-                      x: float,
-                      y: float):
-        cr.save()
-        cr.set_source_rgba(1.0, 0.2, 0, 0.2)
-
-        for temp in range(-140, 140, 10):
-            self.draw_adiabat(cr, x, y, temp, PRESSURE_MAX, LAPSE_RATE_DRY)
-
-        cr.restore()
-
     def draw_sounding(self,
                      cr: cairo.Context,
                      x: float,
@@ -192,7 +149,6 @@ class SkewTGraph():
 
         self.draw_isotherms(cr, x, y)
         self.draw_isobars(cr, x, y)
-        self.draw_adiabats(cr, x, y)
 
         cr.set_source_rgb(1, 0, 0)
         self.draw_sounding(cr, x, y, sounding, lambda s: s.temp)

lib/xmet/thermo.py

@@ -43,16 +43,9 @@ def lcl(temp: float, dewpoint: float) -> float:
     """
     return (temp - dewpoint) / 0.008
 
-def pressure_height(pressure: float) -> float:
-    """
-    Return the approximate altitude, in meters, for a given pressure in
-    millibar.
-    """
-    return (1 - (pressure / 1013.25) ** 0.190284) * 145366.45 * 0.3048
-
 def lapse(temp: float, rate: float, delta: float) -> float:
     """
     Return the temperature of a parcel cooled at either the dry or moist lapse
     rate for a given increase in height (in meters).
     """
-    return temp - (rate * delta)
+    return temp - (rate * (delta / 1000))