Namibian Witches' Rings are mysterious natural phenomenon that occurs in Africa and on several continents, but turned out to be very tough to explain. In this lesson of the Windy.app Meteorological Textbook (WMT) and newsletter for better weather forecasting you will learn more about what the Namibian Witches' Rings are and how do they occur in the most popular theories.
'Witches'' or 'fairy' rings in South-East Africa have been known to the world for over 100 years now. The locals called them 'God's footprints' and have probably known about them for much longer.
The phenomenon looks like perfectly round patches of soil without any plant life whatsoever. Like someone artificially cut out circles, not on their lawn, but on a natural landscape 2400 kilometers long, from south Angola throughout all of Namibia and to the North of South Africa.
The circles can be up to 35 meters in diameter, usually with long grass at the edges. They usually occur in very dry areas far away from civilization — which is why they weren't studied until very recently.
So how are these circles made? It all begins with plants dying on a small patch of soil. After that, the area widens, and, in some cases, even moves slowly. In time, the rings get covered in grass again — this process can take up to 40 years.
Before 2014, it was assumed that this phenomenon is only native to Africa, but afterwards, circles like this were found in West Australia. Not identical, but similar patterns were found in North America and Central Brazil.
Photo: Danita Delimont Creative / Alamy Stock
Over the past decades, scientists proposed several mechanisms of how the rings are made, from plants fighting over water to the activity of underground termites feeding on plant roots. But nobody could fully explain the phenomenon for a long time.
The nature of the rings became clear in 2017, when American ecologists published their research. The authors developed a computer simulation of termites' life that managed to explain the shape and growth of the rings not just by one, but by a combination of several factors.
According to the simulation, the rings are formed in part by underground termite colonies that sometimes leave 'disputed territories' between different colonies' turfs when they can't successfully fight each other for them — that's why there's uneaten grass between the circles.
But the specific dynamic of the rings' appearance could only be explained when moist and dry periods were factored into the simulation, as well as the plants fighting for water and other nutrients contained in the soil.
The simulation has shown that the circles appear around termite colonies during droughts, but grass starts growing more actively when it rains. Lack of plant life allows the rain to moisturize the soil more, and even though termites continue to destroy plant life in the center of the circle, grass on the outskirts of the ring reaches more moist soil with its roots more than its neighbors outside the circle. That's where the contrast comes from: thick tall grass at the border of the circles and its complete lack in the center.
That way, termites, plants and weather are in tight cooperation, and witches' rings are evidence of the work of that complex self-organized system, the research authors conclude. Although, the work emphasizes that this explanation isn't universal, but it does work well specifically Namibian rings.
Photo: Jeremy T. Hetzel / Flickr
Text: Jason Bright, a journalist and a traveller
Cover photo: Cedric Dhaenens / Unsplash