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Classical Köhler Theory vs κ-Köhler Theory in A Study Accommodating Black Carbon (BC) heating - Which one/When to use

 Excellent — you're using the classical Köhler theory to compute the equilibrium saturation ratio (Seq), and you’re asking how this compares to the κ-Köhler theory approach. Let’s explain the difference clearly and provide the equations. Note: As in Nenes (2002), there are 4 scenarios how the presence of BC affect the formed DSD: Scenario 1 (NoHeat scenario): just as the basic assumption in cloud parcel model - there's only latent heat release upon condensation. d T ​/dt = adiabatic cooling + latent heating Scenario 2 (Drop scenario): There's additional heat (reflected by ga value) caused by light absorption of BC in addition to the basic latent heat; this additional heat influence only the Seq of the water droplet. d T ​/dt = adiabatic cooling + latent heating (No change); but Seq change Scenario 3 (External Scenario); The BC is not part of the droplet, i.e. externally mixed particle with the hygroscopic or water absorbing particles, so the BC doesn't heat th...

Building the Cloud Parcel Model on Matlab - Part 2: Create the core ODE system (B. use a realistic particle size distribution (PSD) instead of a single size)

INTRODUCTION ✅ What does generate the aerosol size distribution? They generate the initial aerosol size distribution using a sum of lognormal modes , defined by: Number concentration (N), Geometric mean diameter (rg), Geometric standard deviation (σ). This gives you dN/dlogDp as a function of Dp (dry diameter), independently of composition. Black carbon doesn't influence : Mode centers (rg), Widths (σ), Total number per mode (N). 🟢 These are purely geometrical/statistical parameters for the aerosol distribution. This code block sets up a realistic aerosol size distribution based on a tri-modal lognormal fit commonly used in cloud activation studies, including in Nenes et al. (2001, 2002) . Let's break it down and explain each part: 🔧 Function Overview function [Dp, Nd, kappa, bc_frac] = setup_aerosol_distribution (N_bins) This function generates: Dp : Particle diameters [m] Nd : Number distribution dN/dlogDp [#/m³] kappa : Hygr...