Swiss cloudbreaking license
Some more info on the swiss national license, also called HDF (helicopter departure in fog):
Required conditions: lower cloud ceiling not higher than 200m, max cloud layer thickness 300m, VFR on top. You can do this on controlled airports on the runway (e.g. zurich has published a procedure) or also outside controlled airspace and it's also not even required to start from an airport. There is a common frequency for starts outside controlled aispace.
Again, the main point of this is to get out of an inversion which you cannot underfly (hence the limit of 200m).