Figure S4. The moles of condensed nitric acid against temperature with 1.2 mol % of MEA in total RNCs at fixed total water (TW) or fixed relative humidity (RH) in a chemical system of ammonia, MEA, sulfuric acid and nitric acid. Both curves have the initial moles of ammonia, MEA, HNO3 and H2SO4 as 8.86895×10−8, 1.06427×10−9, 1.11151×10−9­­ and 2.03777×10−11, respectively. The percentage refers to the mol % of MEA in moles of all RNCs (ammonia and MEA) in the system. For open square curve, the initial TW of the system was fixed at 0.07848 mol (equivalent to 60% RH at 263.15 K and 101,325 Pa in 1 m3). For solid square curve, the initial RH of the system was fixed at 60%. The black line is the Tc threshold. When the initial RH of the system was fixed in each simulation, as the temperature increased, the corresponding TW of the system also increased.