
1) Advancing cold air
Found on
https://www.crosswordclues.com/clue/polarfront

Portal axles (or portal gear) are an offroad technology where the axle tube is above the center of the wheel hub. Compared to normal layout, this enables the vehicle to gain a higher ground clearance, as both the axle tube and differential casing are tucked up higher under the vehicle. Due to the gear reduction at the wheel which lessens the torqu...
Found on
http://en.wikipedia.org/wiki/Polarfront
No exact match found.