Source code for arguslib.misc.thermo

import numpy as np


# Altitude conversions

[docs]
def hPa_to_hft(press):
    return 1453.6645 * (1 - (press / 1013.25) ** 0.190284)




[docs]
def hPa_to_km(press):
    return hPa_to_hft(press) * 0.1 / 3.28084




[docs]
def hft_to_hPa(alt):
    return 1013.25 * ((1 - (alt / 1453.6645)) ** (1 / 0.190284))




[docs]
def km_to_hPa(alt):
    return hft_to_hPa(alt * 3.28084 / 0.1)



# Saturation vapour pressure

[docs]
def psat_liq(T):
    return 100 * np.exp(
        -6096.9386 / T
        + 16.635794
        - 0.02711198 * T
        + 1.673953e-5 * T**2
        + 2.433502 * np.log(T)
    )




[docs]
def dpsat_liq(T):
    return psat_liq(T) * (
        -6096.9386 * (-1 / T**2) - 0.02711198 + 1.673953e-5 * 2 * T + 2.433502 / T
    )




[docs]
def psat_ice(T):
    return 100 * np.exp(
        -6024.5282 / T
        + 24.7219
        + 0.010613868 * T
        - 1.3198825e-5 * T**2
        - 0.49382577 * np.log(T)
    )




[docs]
def dpsat_ice(T):
    return psat_ice(T) * (
        -6024.5282 * (-1 / T**2) + 0.010613868 - 1.3198825e-5 * 2 * T - 0.49382577 / T
    )




[docs]
def psat_ice2(T):
    return np.exp(43.494 - 6545.8 / ((T - 273.15) + 278)) / ((T - 273.15) + 868) ** 2




[docs]
def rhl_to_rhi(rhl, T):
    sh = rhl * psat_liq(T)
    return sh / psat_ice(T)




[docs]
def rhi_to_rhl(rhi, T):
    sh = rhi * psat_ice(T)
    return sh / psat_liq(T)



# SAC calcualtions

[docs]
def sac_temp_slow(RH, p, eta=0.35):
    """RH as fraction over liquid
    p in hPa"""
    cp = 1004
    eps = 0.622
    EI = 1.223  # WV eission index for kerosene
    Q = 43.2e6  # Lower heating value
    G = EI * p * 100 * cp / (eps * Q * (1 - eta))

    # Tf = -44.16 + 9.43*np.log(G-0.053) + 0.72*(np.log(G-0.053))**2
    Tf = -46.46 + 9.08 * np.log(G - 0.053) + 0.72 * (np.log(G - 0.053)) ** 2
    Tf = 273.15 + Tf

    Tt = Tf - 0.001
    evalRH = (psat_liq(Tf) - G * (Tf - Tt)) / psat_liq(Tt)
    while evalRH > RH:
        Tt -= 0.01
        evalRH = (psat_liq(Tf) - G * (Tf - Tt)) / psat_liq(Tt)
    return Tt




[docs]
def sac_temp(RH, p, eta=0.35):
    """RH as fraction
    p in hPa"""
    cp = 1004
    eps = 0.622
    EI = 1.223  # WV eission index for kerosene
    Q = 43.2e6  # Lower heating value
    G = EI * p * 100 * cp / (eps * Q * (1 - eta))

    # Tf = -44.16 + 9.43*np.log(G-0.053) + 0.72*(np.log(G-0.053))**2
    Tf = -46.46 + 9.08 * np.log(G - 0.053) + 0.72 * (np.log(G - 0.053)) ** 2
    Tf = 273.15 + Tf

    Tt = Tf - 0.001

    for i in range(6):
        Tt_new = Tt - (Tt - Tf + (psat_liq(Tf) - RH * psat_liq(Tt)) / G) / (
            1 - (RH / G) * dpsat_liq(Tt)
        )
        Tt = Tt_new
    return Tt