Cold spell and Polar front

Cold spell noun - A spell of cold weather.

Polar front and cold spell are semantically related. in advancing front of colder air topic. In some cases you can use "Polar front" instead a noun phrase "Cold spell".

Polar front noun - The front of an advancing mass of colder air.

Cold spell and polar front are semantically related. You can use "Cold spell" instead a noun phrase "Polar front".