Länsituulet

Länsituulet, also known as westerlies, are prevailing winds that blow from the west towards the east in the Earth's middle latitudes. These winds are a significant component of global atmospheric circulation and play a crucial role in weather patterns. They are primarily driven by the temperature difference between the equator and the poles, which creates a pressure gradient. Warm air rises at the equator and moves towards the poles, while cold air sinks at the poles and moves towards the equator. This differential heating, combined with the Earth's rotation (Coriolis effect), deflects these air masses, resulting in the west-to-east flow in the mid-latitudes.

In the Northern Hemisphere, the westerlies are found roughly between 30 and 60 degrees latitude, while in the Southern Hemisphere, they are located in a similar latitudinal band. These winds are generally stronger and more consistent in the Southern Hemisphere due to the absence of large landmasses which can disrupt wind patterns. The westerlies are responsible for transporting weather systems, including storms and precipitation, across continents and oceans. Sailors have historically relied on the westerlies for navigation, particularly in the Southern Ocean, where they are known as the "Roaring Forties," "Furious Fifties," and "Screaming Sixties" due to their strength and persistence. Their influence is vital for climate regulation and the distribution of moisture across various regions of the globe.