Nitrogen oxides and NO2 primary composition in earth’s atmosphere

Abstract

Humans believed Earth was 78% nitrogen (N₂) and 21% oxygen (O₂) until the 2020s. Based on data collected by balloons and satellites since the 1980s, evidence suggests that Earth's atmosphere is composed of complex molecules such as nitrogen dioxide (NO₂) with polar bent molecular structures, similar to water (H₂O). Although nitrogen-oxygen mixing ratios have been recorded for over 50 years, they have often been overlooked in studies of redox reactions, biological systems, and nitrogen-fixing bacteria. Microorganisms, including bacteria in oceans and soils, release nitrous oxides, NO₂, NO, and N₂O, which are abundant in these environments. Nitric oxide (NO) is also among the most prevalent molecules in biological systems; experiments indicate that NO₂ and NO diffuse rapidly across cell membranes. Measurements at altitudes of 10-12 km show a ratio of 1 NO to 2-6 times NO₂, with air density estimates indicating 300-400% more NO₂ compared to NO at the surface. Near the surface, the ratio is approximately ₂:1 NO, similar to the historically accepted 78% nitrogen measurements. This data suggests that the air density of NO₂ is less than 2.05257 g/L or kg/m³, which is about 68% heavier than the standard air density of 1.19 g/L. Ongoing research enhances data models related to atmospheric composition, aerodynamics, climate change, biological processes, materials science, surface redox reactions, and planetary studies.