Description
Used in Aspen until May 2018 release, at which point it was replaced by the formula from Hardy.
Saturation vapor pressure \(E_{sw}\)(mb) at temperature \(t\)(K).
Interpolate from the table \(E_{tbl}\) of vapor pressures if \(ETBL_{MIN} < t < ETBL_{MAX}\), otherwise use the exact (but slower) formula.
Formula
\[E_{sw} = \begin{cases} i = int(\frac{t - ETBL_{MIN}} {ETBL_{STEP}}) \\ f = \frac{fmod (t, ETBL_{STEP})} {ETBL_{STEP}} \\ E_{sw} = (1 - f) ETBL_i + f ETBL_{i+1}, & \text{for } ETBL_{MIN} \lt t \lt ETBL_{MAX} \\ E_3 e^{A \log {T_3 \over t}} e^{(A + B) (1 - \frac{T_3} {t})} & \text{otherwise} \end{cases}\]See Also
PAM II Derived Parameters Constants
Source
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