55 lines
1.7 KiB
Python
55 lines
1.7 KiB
Python
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##
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# This software was developed and / or modified by Raytheon Company,
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# pursuant to Contract DG133W-05-CQ-1067 with the US Government.
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#
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# U.S. EXPORT CONTROLLED TECHNICAL DATA
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# This software product contains export-restricted data whose
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# export/transfer/disclosure is restricted by U.S. law. Dissemination
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# to non-U.S. persons whether in the United States or abroad requires
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# an export license or other authorization.
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#
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# Contractor Name: Raytheon Company
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# Contractor Address: 6825 Pine Street, Suite 340
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# Mail Stop B8
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# Omaha, NE 68106
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# 402.291.0100
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#
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# See the AWIPS II Master Rights File ("Master Rights File.pdf") for
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# further licensing information.
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###
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from numpy import zeros
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from numpy import log
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from numpy import sqrt
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CONST_A = 0.0091379024
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CONST_B = 6106.396
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CONST_C = 223.1986
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CONST_D = 0.0182758048
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CONST_E = 0.37329638
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CONST_F = 41.178204
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CONST_G = 0.0015945203
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CONST_H = 3.498257
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##
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# Calculate condensation pressure from pressure, temperature, and relative
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# humidity
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# @attention: Result may contain NaN
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#
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# @param p: Pressure in millibars
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# @type p: scalar or numpy array
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# @param t: Temperature in degrees Kelvin
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# @type t: scalar or numpy array
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# @param rh: Relative humidity from 0.0 to 100.0
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# @type rh: scalar or numpy array
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#
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# @return: Condensation pressure in millibars
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# @rtype: numpy array of float
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def execute(p, t, rh):
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rhqc = rh.clip(1.0,100.0)
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b = CONST_A * t + CONST_B / t - log(rhqc/100.0)
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tdp = (b - sqrt(b**2.0 - CONST_C)) / CONST_D
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tcp = tdp - (t-tdp) * (-CONST_E + CONST_F / t + CONST_G * tdp)
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q = p * (tcp/t) ** CONST_H
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return q
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