Maybe the ozone layer protects them? Your conclusion that nitrogen molecules in the atmosphere only survive a minute or so during the daytime isclearly wrong;

Maybe the ozone layer protects them? Your conclusion that nitrogen molecules in the atmosphere only survive a minute or so during the daytime isclearly wrong; if it were true, the atmosphere would be about 2% brown nitrogen dioxide like the output of a Birkeland–Eyde reactor a couple of minutes after the sun came up (or more, since the temperature and pressure are lower) and everyone would have died at sunrise today. Or, rather, biochemistry would look almost unimaginably different, having evolved to resist being oxidized by nitric acid. UV breakdown doesn't appear as a significant source in http://nmsp.cals.cornell.edu/publications/factsheets/factsheet39.pdf http://nmsp.cals.cornell.edu/publications/factsheets/factshe... although lightning does. So, if this mechanism is operating at a significant scale in Earth's atmosphere, it's escaped the attention of the scientists who specialize in the terrestrial nitrogen cycle, which seems implausible.