A typical area with a high probability for the initiation of convection is the area of the warm sector in front of and some distance away from a frontal cloud band. Initiation of convection only happens in cases where the troposphere has a specific structure (see Meteorological physical background and Key parameters ). The satellite images above show a number of developing Convective Cells over Central Europe. In both images (IR, VIS) the cells are characterized by more or less bright pixel values indicating high thick and/or multi-level cloudiness. In the IR image (left image) the cells have sharp cloud edges. In contrast, the VIS image only shows sharp cloud edges at the upstream edge of the cloud mass (area close to the weather-active part) while the downstream edge is more fibrous and translucent. This part characterizes the area of the anvil.