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Abstract Ammonia (NH₃) from animal feeding operations (AFOs) is an important source of reactive nitrogen in the US, but despite its ramifications for air quality and ecosystem health, its near‐source evolution remains understudied. To this end, Phase I of the Transport and Transformation of Ammonia (TRANS²Am) field campaign was conducted in the northeastern Colorado Front Range in summer 2021 and characterized atmospheric composition downwind of AFOs during 10 research flights. Airborne measurements of NH₃, nitric acid (HNO₃), and a suite of water‐soluble aerosol species collected onboard the University of Wyoming King Air research aircraft present an opportunity to investigate the sensitivity of particulate matter (PM) formation to AFO emissions. We couple the observations with thermodynamic modeling to predict the seasonality of ammonium nitrate (NH₄NO₃) formation. We find that during TRANS²Am northeastern Colorado is consistently in the NH₃‐rich and HNO₃‐limited NH₄NO₃formation regime. Further investigation using the Extended Aerosol Inorganics Model reveals that summertime temperatures (mean: 23°C) of northeastern Colorado, especially near the surface, inhibit NH₄NO₃formation despite high NH₃concentrations (max: ≤114 ppbv). Finally, we model spring/autumn and winter conditions to explore the seasonality of NH₄NO₃formation and find that cooler temperatures could support substantially more NH₄NO₃formation. Whereas NH₄NO₃only exceeds 1 μg m⁻³∼10% of the time in summer, modeled NH₄NO₃would exceed 1 μg m⁻³61% (88%) of the time in spring/autumn (winter), with a 10°C (20°C) temperature decrease relative to the campaign.