This paper presents a simple methodology to take into account the subgrid effects of wet convective processes to trace vertical motion of air parcels for low-resolution atmospheric models. Such models are used for wind field simulations that serve as input for trajectory models. Air parcels in moist convective regions can thus be vertically transported to the cumulus top level with the short timescale associated with cumulus updrafts. Two cases are presented: wet and dry seasons in Amazonia, showing the differences of trajectories followed by air parcels with and without the methodology. The implications for the interpretation of air chemistry measurements are discussed, and an example using LBA/CLAIRE data is used to point out the usefulness of the convective kinematic trajectory technique presented here. ¿ 2000 American Geophysical Union