The role of radiative cooling and leaf wetting in air–leaf water exchange during dew and radiation fog events in a temperate grassland

•Isotopes are used to study leaf-atmosphere water exchanges during dew and fog.•Different methods were adopted to simulate leaf temperature and conductance.•Radiative cooling induced leaf wetting and a directed vapor flux from atmosphere onto the foliage.•Air-leaf vapor exchange differed by species with varied leaf temperature and conductance.