actinometrical,a.|ˌæktɪnəʊˈmɛtrɪkəl| [f.prec. + -al1.] = actinometric. 1873Atkinson tr.Ganot's Physics 345 The absorptive action which the aqueous vapour in the atmosphere exerts on the sun's heat has been established by a series of actinometrical observations made by Sorel at Geneva.