SciTech Daily  January 1, 2022 In previous studies, the cloud nucleation values of black carbon were indirect measurements. An international team of researchers (UK, China) concurrently measured the concentration of cloud condensation nuclei and black carbon particles near heavily trafficked roads and industrial centers in Wuhan, China. They found that the activation diameter, or the size of the black carbon particle where half of the particles will nucleate and precipitate out, was 144 ± 21 nanometers at 0.2% supersaturation. How these black carbon–containing particles could act as cloud nuclei is determined by their size combined with their coatings, the authors say, […]