In winter, how do the northern hemisphere mid-latitude westerlies typically behave compared to summer?

• A. Weaker and extend further north
• B. Stronger and extend further south
• C. Weaker and extend further south
• D. Stronger and extend further north

Answer: (B)

In winter, the mid-latitude westerlies in the northern hemisphere tend to be stronger and extend further south compared to the summer months. This phenomenon is primarily due to the greater temperature gradient between the polar regions and the mid-latitudes during winter. Cold air masses from the polar areas push southward, while warmer air from the tropics moves northward.

This larger temperature contrast leads to a stronger pressure gradient, which results in enhanced wind speeds and a more pronounced jet stream. The jet stream, which is part of the westerlies, also tends to dip further south during the winter, leading to its extension into lower latitudes. This dynamic is crucial for understanding winter weather patterns, including storm tracks and the potential for severe winter weather in mid-latitude regions.