Abstract: Device for mixing dry and humid air streams of a combined atmospheric cooler employing parallel air streams. The device comprises a wet exchange unit and a dry heat exchange unit which are disposed in parallel in the air stream. The device for mixing the dry and humid air streams comprises surfaces for deflecting the air streams disposed upstream of the wet heat exchange unit and is characterized in that the deflecting surfaces are constituted by at least one channel which is open in the direction of the air outlet of the cooler and which extends in the space located upstream of the wet heat exchange unit. The at least one channel extends from the region in which the humid air stream arrives adjacent the part of the dry heat exchange unit which is the nearest of said region and toward the center of the cooler.