Montrealers who saw a huge black circle floating in the sky over the city on Thursday afternoon witnessed a fairly rare pollution phenomenon.
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A reader transmitted to Journal an impressive image of the event which took place around 1 p.m. near the Victoria Bridge. In the photo, we see a black donut-shaped ring that floats less than 1000 feet from the ground and is made up of several small particles.
“Personally, I had never seen this before,” says Alexandre Parent, meteorologist at Environment Canada.
According to him, it is dust or fine particles from combustion residues. “It is sure that it comes from a source of pollution resulting from human activity”, specifies Mr. Parent.
In more than 30 years of career, meteorologist Gilles Brien also admits to never having seen such a phenomenon in the sky of Montreal.
“It is sure that it comes from the ground because it is quite low. We see something quite curious here. It is surely an industrial cause. For example, we clean a chimney in a factory and the charred dust forms a cloud in the sky, ”says Mr. Brien.
According to the two meteorologists, the phenomenon could also have been produced by combustion from a train, a fire or even fireworks.
“The particles were surely hotter than their outside environment. They thus rose in the sky as with a hot air balloon. With this program, a circular movement is created and it therefore takes the form of a donut, ”explains Alexandre Parent from Environment Canada.
Mr. Parent also says that the weather conditions were met Thursday to see the phenomenon. Winds of only 7 km / h kept the particles from being swept away by squalls.
Harmful for health
Dr. Parisa A. Ariya, professor of chemistry at McGill University, recalls that a similar black ring was observed in September 2018 in the sky over Valleyfield in Montérégie. She adds that these pollutants can be harmful to human health.
“Airborne polluting particles, that is to say aerosols, many of which form condensation, are also the leading cause of premature death in the world according to the World Health Organization”, concludes Dr. Parisa A. Ariya.