fly ash

in atmospheric chemistry
https://doi.org/10.1351/goldbook.F02465
Finely divided particles of ash entrained in flue gases resulting from the combustion of fuel.
Source:
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2190 (https://doi.org/10.1351/pac199062112167)