Two important factors is temperature and liquid water.
My best guess is allergies
Answer : Radiational Cooling
Explanation: Continental polar (cP) or continental arctic (cA) air masses are cold, dry, and stable. These air masses originate over northern Canada and Alaska. They move southward, east of Rockies into the Plains, then eastward.
Plants that live on land require water, sunlight, and a source of nutrients.
