In this sentence I use the two words "sun rise" but Grammarly says I need to change it to "sunrise", I just don't understand why it would suggest that change.
Oof, that's a tough one. "Sunrise" is a noun, a thing, an event, something that can be pointed to. But watching the event happen over time is a "sun rise," I think, because it's a process. Maybe? Sort of? You might be able to use either. That's a pretty sunrise. The sun rises earlier in the summer. The sun rose earlier yesterday. Wake up or you'll miss the sunrise! I have no idea. Paging @Seven Crowns.
I think perhaps Grammarly isn't infallible! The 'sunrise' would be a time of day—an event—used as a noun. Same as 'sunset.' Watching the 'sun rise' would mean you sit and watch the actual orb appearing over the horizon, with your gaze fixed more or less on the orb. It's a noun-plus-verb. If your characters are just out enjoying that time of day, however, 'sunrise' would be correct. You could also watch as the sun set over the hills. But you could also watch the sunset, taking in all the glory of colours, etc, as the landscape lights up, etc. You wouldn't need to be watching the actual sun. You could watch water fall from a spilled glass. You could also watch a waterfall like Niagara.
I would stick with sunrise as one word. True it's a noun, but you're watching the sunrise. You're watching what it is (a noun). I can see how it could be argued to make it two words, and I'm not sure that would be wrong. Still, I think this is something an editor would make one word in the context you've given. I, too, would make it one word in this context.
To me, "sun rise" describes the physical act of the sun going higher into the sky. "Sunrise" includes that, but also encompasses a whole load of other things - the colours of the brightening sky, wildlife waking up, etc. etc.
You're right. There's multiple readings of it. You don't have to use a compound. Lots of compounds are noun-verb joinings and sometimes the emphasis needs to be on the verb, not the noun that is the joined compound. In those cases you'll have two words. It's the only way to keep the verb from being swallowed. Grammarly has a list of compound words in different forms. Sunrise falls into a closed compound form, so if it sees those two words together and it can parse the sentence that they're in to make sense, it will mark it as a mistake. Like the last sentence I wrote, as an example, "in to make sense" cannot be changed to "into make sense" because the grammar would fail when the program parses it, so it won't make that suggestion. Your sentence works both ways though. These programs aren't really intelligent. They're just algorithms. You have to keep that in mind. It's a nice sentence. I like how it's shaped. How you rolled in that extra "probably ever experienced" would normally be superfluous, but here it really builds a swell of rhythm. It makes it so the two halves of the sentence are unbalanced in a pleasing way. (Perfect balance has its place, but not here.) Anyway, the difference is this: sun rise over the ocean (motion of rise is stressed) sunrise over the ocean (placement of sunrise is stressed) Verb vs compound-noun, from above. There's no right answer, I don't think . . . I kind of prefer motion just because it's active. I guess if it were me I would consider doing this: Angelina whispered it all to them as they watched the sun rose over the ocean to the songs of the birds and crickets, and it was the most wonderful thing any of the girls had ever seen, probably ever experienced, in their short lives. I would do that because "they watched" is a form of a look, which is almost always deletable. If the look itself is important, it gets to live, and here it is, but you already state it in "had ever seen." So I'd just let that phrase carry the idea. The bonus is that it shifts rise to rose and that ends the compound word issue. Instead of that filler, I would add another sound to "birds and crickets." Maybe the sound of the surf on the beach? Something done without a comma . . . "the songs of birds and crickets and the slow shush of the surf."
If you're watching the sun do something, like rise, you can say it's a noun and verb, and say "sun rise". If you're saying you're watching the whole episode as we know it in English, then it's the noun "sunrise". I also think the one word verison is used to convey no specific event, like "be up before sunrise" or "each sunrise I've seen is beautiful". In your case, you're not watching A sunrise, you're watching THIS sun come up over the horizon, and you're watching THE sun rise. In your case, I'd put them as two words. Your grammar checker won't check context, which fits in this case. I'd want to say that I'm watching the sun come up over the horizon. Either are ok. I prefer two words.
Thank you all for your suggestions and opinions. It is indeed a situation where there are different options that all work. So, in this example, I am most comfortable using both forms of the word(s): In my view "watched the sun rise from the sea" emphasizes the rising of the sun. It's not just a typical sunrise, it appeared that the sun rose out of the sea. In speaking the person would use a different inflection for the word "rise". That same feeling does not come across when using "sunrise", in which case the second "sunrise" would be redundant and would need to be removed. Interestingly, each instance of "sun rise" in this message is causing the Grammarly plugin to through up the suggestion of changing them to "sunrise".