Many different kinds of cloudiness related to convergence exist, from small scale to synoptic scale. In the manual only
cloud features associated with an Occlusion are called Convergence Cloudiness. It is quite a frequent phenomenon which
can be observed about twice a month. It is more frequent in winter time due to there being more frontal events. About 30% of the Occlusions develop such Convergence Cloudiness. More examples could be found over the Atlantic and noth-western or western Europe. This is also due to the fact that many frontal systems are in a decaying phase when they cross the continent. Observation over sea is easier because there is no orography to interfer´with the process and the cloud formation is seen more clearly. For this study 25 cases were investigated.