Abstract: A ridge ventilating device that allows for the passive ventilation of agricultural buildings and the like, and which device resists the affects of snow or ice and allows for regulation of the flow of air from the building. Pairs of hinged door panels which operate by opening and closing coincidentally with each other, thereby covering and uncovering an elongate ridge passage cut into the ridge or peak of the roof structure. The doors are hingedly attached along the outside edges of the passage so that they open away from each other and create an unobstructed opening in the roof for the air to exhaust through. Each door is pivotally attached to a connecting link which connecting links are in turn connected at a common pivot point to the shaft of a dual-acting air cylinder. The air cylinder thus provides the motion for opening and closing the doors.