The aim of this presentation is to build a bridge between idealized simulations of dry or convectively unstable atmospheres over smooth orography (Schneidereit and Schaer 2000, Stein 2001) and over the Alpine orography (Gheusi and Stein 2001).

Smoother and smoother orographies are generated from the Alpine one. The stationary solution of dry and moist airflow is obtained with the Meso-Nh non-hydrodtatic model. Two nested models have meshes of 10 and 2.5 km. Dry air and moisture budgets are used to quantify the impact of the different scales present in the Alpine orography.

These airflow regimes are compared with the IOP 2B simulation of the MAP experiment (19-20 September 1999). The dry and moist airflow regimes are used to interpret the convection distribution over the Apennins and the Lago Maggiore target area.