Final answer:
A negative phase of the Arctic Oscillation (AO) contributes to colder and snowier weather in Europe and the Eastern U.S. This phase allows Arctic air to move southward, resulting in harsher winter conditions in those regions.
Step-by-step explanation:
A negative phase of the Arctic Oscillation (AO) is typically associated with cold and snowy conditions in Europe and the Eastern U.S. When the AO is in its negative phase, the polar vortex weakens and allows cold air from the Arctic to plunge southward, resulting in lower temperatures and increased likelihood of snowfall in these regions. This contrasts with the positive phase of the AO, where a stronger polar vortex contains the cold air in the polar region, leading to milder winter conditions in mid-latitudes.
For example, during the winter season, areas with Type D climates experience significant cold periods, often resulting in heavy snow. Also, historical climatic events, such as the extraordinary rains in Europe and Asia in the year 1314, led to cold and wet winters, demonstrating how variations in climate phases can have profound effects on weather conditions.