pyrcel.thermo.Seq_approx¶
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pyrcel.thermo.
Seq_approx
(r, r_dry, T, kappa)¶ Approximate κ-Kohler theory equilibrium saturation over aerosol.
Calculates the equilibrium supersaturation (relative to 100% RH) over an aerosol particle of given dry/wet radius and of specified hygroscopicity bathed in gas at a particular temperature, using a simplified expression derived by Taylor-expanding the original equation,
\[S_\text{eq} = \frac{2\sigma_{w} M_w}{RT\rho_w r} - \kappa\frac{r_d^3}{r^3}\]which is valid when the equilibrium supersaturation is small, i.e. in most terrestrial atmosphere applications.
Parameters: r : float
droplet radius, m
r_dry : float
dry particle radius, m
T : float
ambient air temperature, K
kappa: float
particle hygroscopicity parameter
Returns: float
\(S_\text{eq}\) for the given aerosol/droplet system
See also
Seq
- compute equilibrium supersaturation using full theory
kohler_crit
- compute critical radius and equilibrium supersaturation