Based on the provided sources, the reader could be expected to learn about:
how airports in the Northeast are impacted by large amounts of snowfall.
This conclusion is supported by Source 1 (a map indicating the geographical area), Source 2 (snowfall totals that indicate winter weather conditions), and Source 3 (a video showing the congestion at airports during peak winter season). Together, these sources highlight the challenges that airports face due to heavy snowfall and increased passenger traffic during winter months.