1) Air current 2) Current of air 3) Foehn 4) Wind 1) Foehn 
A warm dry wind that descends on the lee side of a mountain.
In geography, a fohn is a hot, dry, local Alpine wind produced by the desiccation of an air current in passing over the mountain ranges and its subsequent heating by compression on being drawn into the denser valley atmosphere.
[n] - a warm dry wind that blows down the northern slopes of the Alps