General comments:

Insoluble aerosol particles are the main source of ice nucleating particles (INPs) in clouds, but their physical and chemical properties have still not been well determined. This manuscript presents analysis of insoluble particles in 12 hailstones collected from 8 hailstorms occurred in China between 2016 and 2021, by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The insoluble particles were grouped into three species by self-organized maps (SOM) and random forest method. The size distribution of the insoluble particles in embryos and different shells of sliced hailstones was analyzed and was fitted with logarithmic normal distributions. The subject is scientifically interesting and is well within the scope of the journal. But some parts of the manuscript are not well presented or not clear. I think the presenting quality should be substantially improved before it can be accepted for publication in ACP. Some more specific comments are as follows.

Specific comments

1. Although a large number of insoluble particles were found in each of the hailstone samples, it is not sure whether and how many those insoluble particles have ever served as ice nuclei during the formation of the embryos and different shells of hailstones, since many of them might be captured during the formation, growth and falling out of the hailstones.
2. Some sentences are not clearly presented to the readers, such as “… simulation due to little regarding species and number concentration of heterogeneous ice-nucleating particles” in the abstract. I suggest the whole text be checked with the help of an English editor.
3. Line 18-19: “Further, classic size distribution modes of organics and dust were performed as logarithmic normal distributions”: not clear.
4. Line 22-23: “Insoluble particles, acting as main heterogeneous ice-nucleating particles in the atmosphere, may indirectly impact precipitation formation”: why indirectly?
5. Line 26-28: “Only few models calculate the number concentration of ice-nucleating particles in clouds, that leads to a misestimation about number concentration of ice particles and large errors in simulation”: not clear to me.
6. Line 31-32: “Measurements of the number concentration and species of ice-nucleating particles, mainly insoluble particles, were conducted by an airborne equipment or laboratory instrument with air parcels”: not clear to me.
7. Line 34-35: “Most field projects sampled air parcels in anvils of convective clouds, cirrus and winter mixed-phase stratiform clouds, keeping airborne equipment in good working condition”: I am not sure what this sentence want to tell.
8. Line 39-41: The logics of paragraph is incorrect.
9. In Table 1, why only one value is provided for the two samples from Guyuan City?
10. In Line 169, Formula (2): why N_used = N_filter?
11. Line 173, formula (3): The inversion form of this formula might be easier to be understood.
12. Line 182: How formula (5) is derived?
13. Line 227-228: “Each number concentration at diameter D total number concentration of insoluble particles with diameter ranging from D−1 μm to D+0.1 μm”, not clear to me;
14. Line 230-231: “Blue and gray bars show the standard deviation of insoluble particles from seven hailstorms and one hailstorm, respectively”: not clear.
15. Line 236-237: “These initial ice particles are likely formed by insoluble particles where heterogeneous nucleation processes”: incomplete sentence.
16. Line 294 and other places: There should be no unit for logarithmic function.

Technical corrections

1. Change “for” to “of” after “description” in line 29;
2. Change “in” to “of” after “suppression” in line 54;
3. Table captions should be provided on top of the tables;
4. Line 116: Change “Ault et al. in 2012 and Kirpes et al. in 2018” to “Ault et al. (2012) and Kirpes et al. (2018)”;
5. Line 117: Remove “Ault et al. 2012; Kirpes et al. 2018”;
6. Line 122: Change “Species of aerosol particles vary regionally” to “Species of aerosol particles vary with sampling location”;
7. Line 166: Formula (1): Change N_dilute to N_diluted;
8. Line 236: Change “droplet” to “droplets”.

Please see attached comments.