The efficiency shown by topographic obstacles in triggering the occurrence of disturbances which can grow and develop as independent eddies is intimately connected to both the rotation and the stratification of the basic, ‘unperturbed’, atmospheric state. The presence of temperature gradients makes the basic state baroclinically unstable; conversion of available potential energy of the basic state into kinetic energy of the disturbance is made possible if a perturbation strong enough and of the appropriate scale is applied. Steep, large scale obstacles embedded in the atmospheric flow very often provide just such a perturbation, acting, therefore, as sources of systems which can develop and influence the weather of regions even very distant from the obstacle itself. The detailed phenomenology of lee cyclogenesis and its numerical modelling still represent a challenge to dynamic meteorology; a review of the most significant results in this field will be presented and some of them will be discussed in some more detail.