The Arctic Oscillation (AO) is a climate pattern that describes variations in atmospheric pressure in the Arctic region. It influences weather conditions in the Northern Hemisphere, particularly during winter. When the AO is in a positive phase, the polar vortex is strong, leading to milder temperatures and less severe winter weather in many areas. Conversely, during a negative phase, the polar vortex weakens, allowing cold Arctic air to spill southward. This can result in colder temperatures and increased snowfall in regions like North America and Europe. The AO is an important factor in understanding seasonal weather patterns and climate variability.