Ecosystems and air quality are affected by the dry deposition of inorganic reactive nitrogen (N_r, the sum of ammonium and nitrate). Its large variability is driven by the large difference in deposition velocity of N when in the gas or particle phase. Here we show that aerosol liquid water and acidity, by affecting gas–particle partitioning, modulate the dry deposition velocity of NH₃, HNO₃, and N_r worldwide. These effects explain the rapid accumulation of nitrate aerosol during haze events.