Westerlies

Definition

Westerlies are prevailing winds that blow from the west to the east between 30 and 60 degrees latitude in both hemispheres. These winds play a crucial role in global atmospheric circulation, influencing weather patterns, ocean currents, and climate across large regions of the Earth. The westerlies are a key component of the mid-latitude weather systems and are responsible for the movement of storm systems and the exchange of air masses.

5 Must Know Facts For Your Next Test

1. The westerlies are most prominent in the mid-latitudes, where they can greatly influence the development and movement of cyclones and anticyclones.
2. These winds are typically stronger during the winter months due to increased temperature gradients between polar and tropical air masses.
3. The westerlies can interact with local topography, leading to phenomena such as orographic lifting, which can cause increased precipitation on windward slopes.
4. In the Southern Hemisphere, the westerlies have fewer landmasses to obstruct them, making them generally stronger and more consistent than in the Northern Hemisphere.
5. The westerlies play an important role in ocean currents, as they help drive surface currents like the North Atlantic Drift, impacting regional climates.

Review Questions

• How do westerlies affect weather patterns in mid-latitude regions?
  • Westerlies are crucial in shaping weather patterns in mid-latitude regions because they transport warm and cold air masses, leading to the formation of cyclones and anticyclones. As these winds blow from west to east, they carry moisture-laden air over land, which can result in precipitation. The interaction of westerlies with local geographic features can further intensify storms or create areas of calm weather.
• Discuss how seasonal changes influence the strength and behavior of the westerlies.
  • Seasonal changes significantly impact the strength and behavior of the westerlies. During winter months, temperature differences between polar regions and tropics become more pronounced, leading to stronger westerly winds. This increase in strength can enhance storm activity and contribute to more dynamic weather systems. In contrast, during summer, the westerlies may weaken as temperature gradients diminish, resulting in more stable weather patterns.
• Evaluate the impact of westerlies on global climate systems and their role in oceanic circulation.
  • Westerlies play a vital role in global climate systems by influencing both atmospheric circulation and oceanic currents. These winds help distribute heat across latitudes by moving warm air poleward while bringing cooler air toward the equator. Additionally, they drive surface ocean currents such as the North Atlantic Drift, which moderates climate in Western Europe. This interplay between wind patterns and ocean circulation is essential for maintaining climate stability and can have profound implications for weather extremes and regional climates around the world.

Related terms

Trade Winds: The trade winds are prevailing easterly winds found in the tropics, blowing from east to west between the equator and 30 degrees latitude.

Polar Easterlies: Polar easterlies are cold winds that blow from the east to the west near the poles, generally occurring between 60 degrees latitude and the poles.

Jet Stream: The jet stream is a fast-flowing air current in the atmosphere, located at higher altitudes, which can influence weather patterns and the path of storms.