Fig. 6. Representative dynamic observation of phase changes as water uptake by field-collected particles at (a) 1% RH, (b) 70% RH, (c) 80% RH, (d) 90% RH, (e) 97% RH, and (f) 99% RH. Particles indicated by black arrows are examples of organic-rich particles, which show a solid phase state particle transit to semisolid state at 70% RH. Particles indicated by orange arrows are examples of ambient particles contain inorganic species, which we did not investigate in this study.