In meteorology, when a cold one has a close encounter with a warm one & takes it over, it's called an occluded one
[DOC] [TLE] Meteorology, Part 2 (Active Weather), Langley Flying School [PAR] A warm front is the trailing edge of a cold air mass, marked in red, or in black ... 
the warm air to be suspended aloftthis is referred to as an occluded front, or 
occlusion.