[Python-modules-commits] [python-pysolar] 21/42: Calculate pressure and temperature from elevation

[Wolfgang Borgert]

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debacle pushed a commit to tag 0.6
in repository python-pysolar.

commit c2779f3e3163cc9f56d0a1995bd763f80eab4b5d
Author: seanth <seanth at gmail.com>
Date:   Mon Apr 14 15:23:34 2014 -0600

    Calculate pressure and temperature from elevation
    
    created new functions for calculating pressure (in pascals) and
    temperature (in K) from elevation.
    
    Added some unit tests to testsolar.py for the new calculations
---
 Pysolar/elevation.py | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 Pysolar/testsolar.py | 11 +++++++++-
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/Pysolar/elevation.py b/Pysolar/elevation.py
new file mode 100644
index 0000000..16a0709
--- /dev/null
+++ b/Pysolar/elevation.py
@@ -0,0 +1,62 @@
+#!/usr/bin/python
+
+#    Copyright Sean T. Hammond
+#
+#    This file is part of Pysolar.
+#
+#    Pysolar is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    Pysolar is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License along
+#    with Pysolar. If not, see <http://www.gnu.org/licenses/>.
+
+"""Various elevation-related calculations
+
+"""
+import math
+
+def GetPressureWithElevation(h, Ps=101325.00, Ts=288.15, Tl=-0.0065, Hb=0.0, R=8.31432, g=9.80665, M=0.0289644):
+	#This function returns an estimate of the pressure in pascals as a function of elevation above sea level
+	#NOTE: This equation is only accurate up to 11,000 meters
+	#NOTE: results might be odd for elevations below 0 (sea level), like Dead Sea.
+	#h=elevation relative to sea level (m)
+	#Ps= static pressure (pascals) = 101325.00 P
+	#Ts= standard temperature (kelvin) = 288.15 K
+	#Tl= temperature lapse rate (kelvin/meter) = -0.0065 K/m
+	#Hb= height at the bottom of the layer = 0
+	#R= universal gas constant for air = 8.31432 N*m/s^2
+	#g= gravitational acceleration for earth = 9.80665 m/s^2
+	#M= Molar mass of Earth's atmosphere = 0.0289644 kg/mol
+	#P=Ps*(Ts/((Ts+Tl)*(h-Hb)))^((g*M)/(R*Tl))
+	#returns pressure in pascals
+	if h>11000.0: print"WARNING: Elevation used exceeds the recommended maximum elevation for this function (11,000m)"
+	theDenominator = Ts+(Tl*(h-Hb))
+	theExponent=(g*M)/(R*Tl)
+	return Ps*(Ts/theDenominator)**theExponent
+
+def GetTemperatureWithElevation(h, Ts=288.15, Tl=-0.0065):
+	#This function returns an estimate of temperature as a function above sea level
+	#NOTE: this is only accurate up to 11,000m
+	#NOTE: results might be odd for elevations below 0 (sea level), like Dead Sea.
+	#Ts= standard temperature (kelvin) = 288.15 K
+	#Tl= temperature lapse rate (kelvin/meter) = -0.0065 K/m
+	#returns temp in kelvin
+	return Ts+(h*Tl)
+
+def ElevationTest():
+	print "Elevation(m) Pressure(Pa) Temperature(K)"
+	h=0
+	for i in range(11):
+		P=GetPressureWithElevation(h)
+		T=GetTemperatureWithElevation(h)
+		print "%i %i %i" % (h, P, T)
+		h=h+1000
+
+
diff --git a/Pysolar/testsolar.py b/Pysolar/testsolar.py
index 05a3bb7..073b884 100644
--- a/Pysolar/testsolar.py
+++ b/Pysolar/testsolar.py
@@ -22,6 +22,7 @@
 import solar
 import constants
 import julian
+import elevation
 import datetime
 import unittest
 
@@ -56,13 +57,15 @@ class testSolar(unittest.TestCase):
 		self.projected_radial_distance = solar.GetProjectedRadialDistance(self.elevation, self.latitude)
 		self.projected_axial_distance = solar.GetProjectedAxialDistance(self.elevation, self.latitude)
 		self.topocentric_sun_right_ascension = solar.GetTopocentricSunRightAscension(self.projected_radial_distance,
-		    self.equatorial_horizontal_parallax, self.local_hour_angle, self.apparent_sun_longitude, self.true_ecliptic_obliquity, self.geocentric_latitude)
+		self.equatorial_horizontal_parallax, self.local_hour_angle, self.apparent_sun_longitude, self.true_ecliptic_obliquity, self.geocentric_latitude)
 		self.parallax_sun_right_ascension = solar.GetParallaxSunRightAscension(self.projected_radial_distance, self.equatorial_horizontal_parallax, self.local_hour_angle, self.geocentric_sun_declination)
 		self.topocentric_sun_declination = solar.GetTopocentricSunDeclination(self.geocentric_sun_declination, self.projected_axial_distance, self.equatorial_horizontal_parallax, self.parallax_sun_right_ascension, self.local_hour_angle)
 		self.topocentric_local_hour_angle = solar.GetTopocentricLocalHourAngle(self.local_hour_angle, self.parallax_sun_right_ascension)
 		self.topocentric_zenith_angle = solar.GetTopocentricZenithAngle(self.latitude, self.topocentric_sun_declination, self.topocentric_local_hour_angle, self.pressure, self.temperature)
 		self.topocentric_azimuth_angle = solar.GetTopocentricAzimuthAngle(self.topocentric_local_hour_angle, self.latitude, self.topocentric_sun_declination)
 		self.incidence_angle = solar.GetIncidenceAngle(self.topocentric_zenith_angle, self.slope, self.slope_orientation, self.topocentric_azimuth_angle)
+		self.pressure_with_elevation = elevation.GetPressureWithElevation(1567.7)
+		self.temperature_with_elevation = elevation.GetTemperatureWithElevation(1567.7)
 
 	def testGetJulianDay(self):
 		self.assertAlmostEqual(2452930.312847, self.jd, 6) # value from Reda and Andreas (2005)
@@ -134,6 +137,12 @@ class testSolar(unittest.TestCase):
 	def testGetIncidenceAngle(self):
 		self.assertAlmostEqual(25.18700, self.incidence_angle, 3) # value from Reda and Andreas (2005)
 
+	def testPressureWithElevation(self):
+		self.assertAlmostEqual(83855.90228, self.pressure_with_elevation, 4)
+
+	def testTemperatureWithElevation(self):
+		self.assertAlmostEqual(277.9600, self.temperature_with_elevation, 4)
+
 suite = unittest.TestLoader().loadTestsFromTestCase(testSolar)
 unittest.TextTestRunner(verbosity=2).run(suite)
 

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