Answer: mP.
Step-by-step explanation:
- Nor'easter is a cyclone that occurs in the north Atlantic ocean. It is accompanied by heavy rain or snow at cold temperatures and it causes the maximum damage during the winter season.
- The air masses responsible for its formation are the mP (Maritime polar) air masses which are known for being unstable as well as cool and moist.
- The mP air masses from the north Atlantic are responsible for causing nor'easters storm.