e_eq_mixed_mk

typhon.physics.e_eq_mixed_mk(T)[source]

Return equilibrium pressure of water with respect to the mixed-phase.

The equilibrium pressure over water is taken for temperatures above the triple point \(T_t\) the value over ice is taken for temperatures below \(T_t–23\,\mathrm{K}\). For intermediate temperatures the equilibrium pressure is computed as a combination of the values over water and ice according to the IFS documentation:

\[\begin{split}e_\mathrm{s} = \begin{cases} T > T_t, & e_\mathrm{liq} \\ T < T_t - 23\,\mathrm{K}, & e_\mathrm{ice} \\ else, & e_\mathrm{ice} + (e_\mathrm{liq} - e_\mathrm{ice}) \cdot \left(\frac{T - T_t - 23}{23}\right)^2 \end{cases}\end{split}\]

References

IFS Documentation – Cy45r1, Operational implementation 5 June 2018, Part IV: Physical Processes, Chapter 12, Eq. 12.13, https://www.ecmwf.int/node/18714

import numpy as np
import matplotlib.pyplot as plt
from typhon import physics

T = np.linspace(245, 285)
fig, ax = plt.subplots()
ax.semilogy(T, physics.e_eq_mixed_mk(T), lw=3, c='k', label='Mixed')
ax.semilogy(T, physics.e_eq_ice_mk(T), ls='dashed', label='Ice')
ax.semilogy(T, physics.e_eq_water_mk(T), ls='dashed', label='Water')
ax.set_ylabel('Vapor pressure [Pa]')
ax.set_xlabel('Temperature [K]')
ax.legend()

plt.show()

(Source code, png, hires.png, pdf)

../_images/typhon-physics-e_eq_mixed_mk-1.png

Parameters:: T (float or ndarray) – Temperature [K].