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