Authors,

After reading through the referee comments and your responses, I am confident that the manuscript will soon be acceptable for final publication. There are a few areas that I would like you to improve upon somewhat more before final acceptance, and I’ve listed these below. Hopefully these comments will be relatively efficient for you to process edits for. There are also still some areas that require minor English language edits, but these will likely be corrected during the copy-editing process by the Copernicus staff.

Alex Huffman

General comments:
Comment 1: Section 2.1, Description of the microcosms – I think the addition of this section was important, but I’m still a bit confused by how these microcosms were produced in your experiments. I suggest adding a sentence after the first in the section to say something like: “Microcosms were developed by …” and then follow with an few-sentence, explicit overview of how you got droplets of cloud-like water. It wasn’t clear to me whether the water was collected from clouds and processed in some way or synthetically produced. Make this very clear at the beginning of this section before you move into the details of the radiation that was supplied to the microcosms.

Comment 2: For Figures 1,2, and 4, I think it would benefit the reader to consider using color as a part of the traces/markers. Since color figures can be reproduced in the final version at no additional cost, I think this edit would improve readability, especially in the relatively complicated Figure 1. You might consider coloring in such a way as to make one theme of colors to be biotic and another theme to be abiotic, etc.

Connected to this comment, e.g. at L222 where Figure 1 is discussed, the interpretation of the figure takes some time for the reader. I suggest specifically referring to which trace you discuss by the color that you change it to in the final form, i.e. “the degradation of hydrogen peroxide is clearly effective … (Fig. 1, blue trace)”

Comment 3: Reviewer #2 suggested major manuscript revision, including several specific areas of improvement. My feeling is that some of these suggestions for improvement are reasonable, but can be handled with only mild additional discussion. One area relates to their first major comment about the differences between the laboratory setup and the ‘real’ cloud water environment. I agree with your response that a full analysis of this is beyond the scope of the manuscript. However, I suggest taking some of your response to the referee’s question and including these major ideas somewhere in the manuscript – probably the final discussion, Section 4.

Comment 4: The same response is true for the second comment from Referee #2 (“In the studies described here …”). I think it would be worthwhile to add an additional sentence or two of discussion regarding how an atmospheric chemist might treat or use these data. In this context it is fine to say what would need to be done before it could be modeled or scaled, and how it might be important or complicated. I encourage you to use thoughts you have already formulated and put into the response document. Take the most important of these and add a few ideas to the discussion.


Technical comments and typos:
L61: Typo – remove “have been”

L106: New sentence – I would suggest moving this sentence a bit one sentence higher into the paragraph so that the sentence beginning “This work will …” can be the last sentence of the introduction.

L114: I was a bit confused by how to interpret the “up to 30%” comment about the UV radiation. 30% of what, of the light energy emitted from the chosen source? Please clarify this.

Figure 1 caption: I suggest changing to: “Where error bars are not visible they are smaller than the symbol.” Also, the two sentence previous to this are almost exactly redundant. Keep only one of those two sentences.

Figures 1, 2, and 4 are produced at low resolution. After acceptance, please make sure to submit higher resolution versions of these figures.

Table 1: Is there a reason why no standard errors are reported for section (a), abiotic degradation? It would be better if these were included.

Authors,

Thank you for your detailed responses to each stage of reviews. I'm happy to recommend the paper for publication at this point. Thank you for your submission to ACP.

Regards,

Alex Huffman