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On This Day In 1950: The Sun and Moon Turn Blue
September 25, 2022 at 07:52 PM EDT
By WeatherBug's Richard Romkee
On this day in 1950, a smoke plume turned the sun and moon blue for a large part of the Northern Hemisphere.
On June 1, 1950 in northeastern British Columbia, Canada, a wildfire broke out and slowly began to spread. The fire, called the Chinchaga fire, was in a rural area, and local firefighting crews were not allowed to fight the fire until it threatened a major transportation route or it came within 10 miles of a city.
The fire continued to slowly grow unchecked, with strong winds occasionally pushing it quickly to the east in five major runs, the last of which occurred in mid-Septmeber. By September 24, 1950, the fire had grown to become the largest fire on record in North America and was producing copious amounts of thick, dark smoke. By the time a snowstorm ended the fire’s run in October, the conflagration had burned anywhere from 5,500 and 6,600 square miles of forest.
This smoke was transported downwind, first to the northeast then eventually to the south and east. As this smoke pushed away from the fire zone, it caused various problems mainly in central Canada. These problems included blotting out the sun entirely in Sarnia and Toronto. Toronto experienced a strong surge in electricity demands as streetlights and buildings needed to be illuminated. The power grid in the area couldn’t handle this surge, unfortunately, and power outages were common in response to the 200,000 kilowatt hour increase in demand.
Beyond the power grid, a search for a downed U.S. Air Force airplane was grounded due to the smoke, with animals also changing their daily sleep patterns in response to the daytime darkness. One unusual positive of this event in Canada, however, involved crops: the weather forecast that night called for morning frost which would have certainly damaged local orchards and caused significant losses, but the smoke prevented efficient nighttime cooling and saved the crops from damage.
As the dense smoke continued eastward, it spread out and thinned while staying far from the surface. This meant that while the smoke would still have impacts in the eastern U.S. and eastern Canada, it would not be detectable by those on the ground. An area of high pressure over the eastern U.S. also trapped part of the smoke plume for several days, while another plume of smoke moved toward Europe and was detected over the United Kingdom by September 27.
The smoke plume was not as impactful after September 24, nicknamed “Black Sunday” for the wide-ranging dense overcast that impacted a large area that day, but it did stick around and blocked some sunlight leading to cooler temperatures in the eastern U.S. for several days afterward.
After the darkest day, smoke became less and less visible, but those underneath it noticed something odd about the sun and moon in the sky – they were tinted blue. Why was this the case? The smoke particles that remained in the sky were too thinly spread out to fully block sunlight, but they were the perfect size to scatter most wavelengths of sunlight. Incoming rays of sunlight were mostly prevented from reaching the sunlight, but the blue wavelengths were able to breach the smoky layer of atmosphere turning the celestial bodies they emerged from a shade of blue.
Though the Chinchaga fire caused no injuries or damage directly, it serves an important lesson: the atmosphere is a complex and interconnected system, and an event thousands of miles away can still cause significant problems.
Source: Wikipedia.org
On June 1, 1950 in northeastern British Columbia, Canada, a wildfire broke out and slowly began to spread. The fire, called the Chinchaga fire, was in a rural area, and local firefighting crews were not allowed to fight the fire until it threatened a major transportation route or it came within 10 miles of a city.
The fire continued to slowly grow unchecked, with strong winds occasionally pushing it quickly to the east in five major runs, the last of which occurred in mid-Septmeber. By September 24, 1950, the fire had grown to become the largest fire on record in North America and was producing copious amounts of thick, dark smoke. By the time a snowstorm ended the fire’s run in October, the conflagration had burned anywhere from 5,500 and 6,600 square miles of forest.
This smoke was transported downwind, first to the northeast then eventually to the south and east. As this smoke pushed away from the fire zone, it caused various problems mainly in central Canada. These problems included blotting out the sun entirely in Sarnia and Toronto. Toronto experienced a strong surge in electricity demands as streetlights and buildings needed to be illuminated. The power grid in the area couldn’t handle this surge, unfortunately, and power outages were common in response to the 200,000 kilowatt hour increase in demand.
Beyond the power grid, a search for a downed U.S. Air Force airplane was grounded due to the smoke, with animals also changing their daily sleep patterns in response to the daytime darkness. One unusual positive of this event in Canada, however, involved crops: the weather forecast that night called for morning frost which would have certainly damaged local orchards and caused significant losses, but the smoke prevented efficient nighttime cooling and saved the crops from damage.
As the dense smoke continued eastward, it spread out and thinned while staying far from the surface. This meant that while the smoke would still have impacts in the eastern U.S. and eastern Canada, it would not be detectable by those on the ground. An area of high pressure over the eastern U.S. also trapped part of the smoke plume for several days, while another plume of smoke moved toward Europe and was detected over the United Kingdom by September 27.
The smoke plume was not as impactful after September 24, nicknamed “Black Sunday” for the wide-ranging dense overcast that impacted a large area that day, but it did stick around and blocked some sunlight leading to cooler temperatures in the eastern U.S. for several days afterward.
After the darkest day, smoke became less and less visible, but those underneath it noticed something odd about the sun and moon in the sky – they were tinted blue. Why was this the case? The smoke particles that remained in the sky were too thinly spread out to fully block sunlight, but they were the perfect size to scatter most wavelengths of sunlight. Incoming rays of sunlight were mostly prevented from reaching the sunlight, but the blue wavelengths were able to breach the smoky layer of atmosphere turning the celestial bodies they emerged from a shade of blue.
Though the Chinchaga fire caused no injuries or damage directly, it serves an important lesson: the atmosphere is a complex and interconnected system, and an event thousands of miles away can still cause significant problems.
Source: Wikipedia.org