pyrcel.thermo.Seq_approx¶
- 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:
- rfloat
droplet radius, m
- r_dryfloat
dry particle radius, m
- Tfloat
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