In the current study an analytical formulation for the geostrophic adjustment of an initial pointlike pulse of heat is developed on the basis of the linearized, hydrostatic Boussinesq-equations. The heatpulse is thought to model a convective cloud or an error within the prediction of a cloud. A time-dependent solution for both the transient and the balanced flow components is derived from the analytical model. The solution is the Green's function for the mathematical problem, which allows for the simple construction of a solution for arbitrary forcings. From the solution, the temporal and spatial adjustment scales are identified, and diagnostics are developed that allow an identification of the geostrophic adjustment process in numerical simulations. The predictions are then tested within highly idealized numerical simulations. The high level of agreement between error growth characteristics in the numerical perturbation experiments and the analytical predictions suggests that geostrophic adjustment following convective heating plays a major role in upscale error growth through the mesoscales.