{
  "id": 7797346,
  "title": "The Effects of Polar Night and Day on Arctic Air Masses",
  "url": "https://urgent.news/2026/09/16/the-effects-of-polar-night-and-day-on-arctic-air-masses",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-16T13:15:19.000Z",
  "source": {
    "name": "Eos",
    "slug": "eos",
    "url": "https://eos.org/features/the-effects-of-polar-night-and-day-on-arctic-air-masses"
  },
  "original_language": "en",
  "account": "In late April 2026, a weakened polar vortex caused a cold Arctic air mass to affect European crops, as temperatures dropped 10°C–15°C below seasonal averages, particularly impacting vineyards and orchards. Though cold air outbreaks (CAOs) are not rare, they have intensified due to rapid changes in the Arctic climate system, with enhanced warming and loss of sea ice playing a role. These air mass transport events link the Arctic atmosphere with midlatitudes and can trigger extreme weather. As cold, dry air from the Arctic and warm, moist air influxes influence each other, they transform significantly as they travel over open ocean and sea ice, altering temperature, moisture content, cloud patterns, and precipitation. Seasonal variations, particularly related to solar radiation (absent during polar night), play a crucial role in these transformations, though the underlying processes are not fully understood. Improving our understanding of cloud development and the atmospheric boundary layer during air mass transport events, especially during the polar night, could help us better predict the impacts of these events. The Arctic is a key player in global climate regulation, with atmospheric interactions between the Arctic and midlatitudes primarily occurring through meridional air mass transports, including CAOs and warm air intrusions (WAIs). These interactions regulate near-surface air temperatures, sea ice extent, cloud formation, and the exchange of energy, moisture, and pollutants. Warm air intrusions, for example, increase near-surface air temperatures and promote cloud development that further heats the Arctic surface, potentially hindering sea ice growth. To better understand and model these processes, ongoing observations and advanced modeling techniques are necessary, especially given the significant seasonal contrasts between polar night and polar day. During polar night, the Arctic predominantly loses energy, while in polar day, it gains energy, leading to a major shift in the radiative energy budget. This annual back-and-forth affects the atmospheric boundary layer, causing temperature inversions that inhibit vertical mixing in winter and promoting more vertical mixing in summer. These radiative changes, in turn, influence cloud formation, sea ice growth, and large-scale atmospheric circulation.",
  "summary": "Cold air outbreaks and warm air intrusions link Arctic and midlatitude weather and climate. But a lack of data on these events, especially in winter, limits our understanding.",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}