Cloud condensation activation and adsorption measurements on metal oxides and mineral samples

This dataset contains experimental measurements of cloud condensation activation and gas adsorption for selected insoluble metal oxide and mineral powder samples, together with associated model output files. The data support the manuscript by Laaksonen et al., "Cloud condensation experiments probe nanoscale effects on water vapor adsorption by insoluble particles."

The investigated metal oxides are: Al2O3 (sample #1 and #2), Fe2O3, SnO2, TiO2, NiO, PbO, and CuO.

The investigated minerals are: K-feldspar, kaolinite, kaolin, and illite.

The cloud condensation data provide critical supersaturation values as a function of particle size. The adsorption data include water vapor adsorption isotherms and nitrogen adsorption isotherms measured for the same materials. In addition, the dataset includes model output files: the f(X,N,B) correction factor as a function of number of adsorbed water monolayers for selected particle sizes and FHH B parameter values; a comparison table of experimental and modelled critical supersaturation values with their ratios across the full diameter range for all 12 substances; the critical supersaturation as a function of number of adsorbed layers at activation for four FHH correction methods; and the number of adsorbed layers at activation as a function of particle diameter for all 12 substances.

CONTENTS

1. Cloud condensation activation measurements 

Folder: CCN_activation_data.zip

This dataset contains cloud condensation nuclei activation data reporting the critical supersaturation (S*) at which 50% of particles activate as cloud droplets as a function of dry particle diameter.

Each file corresponds to a specific material  *_AAC_50.txt and contains:

• Dp: Dry particle diameter (nm)
• dDp: Uncertainty in dry particle diameter (nm)
• S*: Critical supersaturation at 50% activation. (P/P0 -1)
• dS: Measurement uncertainty in S*

2. Water and Nitrogen adsorption isotherm measurements

Folders: H2O isotherms.zip and N2_isotherms.zip

The dataset includes nitrogen adsorption isotherms (adsorption branch, *_N2_N_ad.dat) and water adsorption isotherms (desorption branch, *_H2O_N_de.dat). Each file contains a header with references to the original experimental filenames and data in two columns:

• P/P0: Saturation ratio
• N_ads  (N_des): Number of adsorbed water or nitrogen monolayers in the adsorption (desorption) branch

3. MODEL OUTPUT AND COMPARISON DATA

3.1 SSw_comparison_table.csv

Data for Figures 1 and 3a.

Critical supersaturation (SSw, %) for all 12 substances across a particle diameter grid of 40-1000 nm.

Contains experimental SSw values with uncertainties, model estimates from three FHH-based parameterisations (original, size-corrected, and size+fractal-corrected), the Kelvin-equation reference curve, and the ratios of modelled to experimental SSw. Rows where no experimental measurement exists at a given diameter contain model values only.

• Substance: sample identifier
• Dp (nm): particle diameter (nm)
• dDp (nm): uncertainty in particle diameter (nm)
• SSw_exp: experimental critical supersaturation (%)
• dSSw_exp: uncertainty in experimental SSw (%)
• SSw_kelvin: Kelvin-equation SSw (%) — pure water limit
• Ssw_FHH: modelled SSw (%) — FHH original
• SSw_FHH(D): modelled SSw (%) — FHH with size correction
• SSw_FHH(D,f): modelled SSw (%) — FHH with size and fractal correction
• ratio_SSw_FHH: SSw_FHH / SSw_exp
• ratio_SSw_FHH(D): SSw_FHH(D) / SSw_exp
• ratio_SSw_FHH(D,f): SSw_FHH(D,f) / SSw_exp
• data_type: "experimental + model" or "model only"

3.2 fXNB_data.csv

Data for Figure 2.

Theoretical f(X,N,B) correction factor as a function of number of adsorbed water monolayers N (range 1-2000), computed for three particle diameters (10, 100, 1000 nm) and three FHH B parameter values (1.01, 2, 3).

• Diameter_nm : dry particle diameter (nm)
• B_value: FHH B parameter
• N_mono: number of adsorbed water monolayers
• fXNB: f(X,N,B) correction factor (dimensionless, 0-1)

3.3 SSw_vs_N.csv

Data for Figure 3b.

Critical supersaturation SSw (%) as a function of number of adsorbed water layers N at activation, for four correction methods applied to K-Feldspar (diameter = 300 nm, A = 3.46, B = 2.14, B_corr = 1.06). N range: 10-10000.

• Method: correction method (Uncorrected, Size_corrected, Fractal_corrected, Size_and_fractal_corrected)
• N: number of adsorbed water monolayers at activation
• SSw: critical supersaturation (%)

3.4 N_vs_diameter.csv

Data for Figure 3c.

Number of adsorbed water layers N at CCN activation as a function of particle diameter, for all 12 metal oxide and mineral substances. Diameter range: 40-1000 nm. N range: 10-2000.

• Substance: sample identifier
• Diameter_nm: particle diameter (nm)
• N: number of adsorbed water layers at critical supersaturation

NOTES

- NA indicates missing or not applicable values (e.g., experimental columns for model-only rows, ratio values where no experimental reference exists, or model values that did not converge).
- File headers within each CSV provide additional metadata, including column descriptions.