Strong Driving Force
The Antarctic Circumpolar Current (ACC), the largest known ocean current, is responsible for carrying cold water rich in nutrients to the ocean, which gives rise to a healthy marine ecosystem. These mighty currents are driven by none other than the westerlies at a speed of 4 kmph.
The movement of air at all the levels of the atmosphere over the surface of the Earth is known as 'atmospheric circulation'. The main forces behind this phenomenon are solar energy, which heats the atmosphere at various intensities at the equator, the middle latitudes, the poles, and the rotation of the Earth on its axis. One such atmospheric circulation along the two hemispheres are the prevailing westerlies.
Definition of Prevailing Westerlies
The winds that move toward the poles between 30° and 60° latitude appear to curve to the East. As winds are named according to the direction they originate, these winds are called prevailing westerlies. Along the Northern Hemisphere, these winds are responsible for many of the weather movements across the United States and Canada.
Let us get to know more about this geographical phenomenon.
Facts about Prevailing Westerlies
The prevailing westerlies are also known as 'anti-trades' or 'westerlies'. These winds are created in the middle latitudes between 30° and 60°, and they blow from the high-pressure areas in the horse latitudes towards the poles. These winds blow in the direction from west to east.
In meteorological terms, they are also known as 'Ferrell cells', as they are named after American meteorologist William Ferrell (1817 - 1891), who discovered them in 1856.
These winds tend to blow in the direction from southwest to the northeast in the Northern Hemisphere and from the northwest to the southeast in the Southern Hemisphere due to the Coriolis effect.
They tend to grow stronger during winter when there is low pressure over the poles, and weaker during the summer when there is high pressure over the poles.
These winds are important as they develop strong ocean currents in both the hemispheres that aid in the sailing route of ships crossing the Atlantic and Pacific Oceans. They blow strongly in the Southern Hemisphere due to less available land mass.
These winds carry warm equatorial currents and winds to the western coasts of the continents in the Southern Hemisphere between the southern latitudes of 40°and 50°, where they are known as the 'Roaring Forties'. These winds were important during the 1600s to 1800s for the shipping industry as it aided to help sail from the Indian Ocean back to Europe via the eastern route.
Tropical cyclones crossing the subtropical ridge axis into the Westerlies bend back due to an increased westerly flow.
The prevailing westerlies affect the climatic conditions of most of the colder European countries by bringing in warm winds as they blow across the North Atlantic drift, Northern Spain, most of France, Germany to Western Poland, the British Isles, while the coastal areas of Scandinavia experience warm climate due to these winds.
These winds carry remnants of tropical storms formed in the Caribbean and Eastern USA to other parts of Europe. Mostly, the Netherlands and the United Kingdom experience a disproportionately high number of tornadoes, but these are not very destructive. They also pick up moisture from the oceans and cause precipitation in the European countries with most of it affecting the Alps.
These winds bring rain from the Atlantic Ocean, and their position shifts southward during winter and rises further north in summer.
'The European Monsoon' which is also known as the 'Return of the Westerlies' occurs due to the prevailing westerlies blowing over the Atlantic, where they become loaded with wind and rain. These are cyclonic and low-pressure precipitation winds that travel along the Gulf Stream. These winds are common during the European winter, but ease out during spring; it accelerates again in June, which is why this phenomenon is known as 'Return of the Westerlies'. It affects Europe's Northern Atlantic coastline, such as Ireland, Great Britain, the Benelux countries, Western Germany, Northern France, and parts of Scandinavia.
The prevailing westerlies play a primary role as one of five primary wind zones that make up our Earth's atmospheric circulatory system, and are influential in climatic as well as atmospheric changes.