Front occlus trowal en - Public domain map

Occlusion where the cold air catch up to the warm front in the cross-section shown by A-B. There is two types : In a cold occlusion, the air mass overtaking the warm front is cooler than the cool air ahead of the warm front, and plows under both air masses. In a warm occlusion, the air mass overtaking the warm front is not as cool as the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air.