Wednesday May 10, 2023
Current orange sunsets - with orange solar halos - are breathtaking to look at but come with a price. They are a result of the wildfires in Alberta, Canada. As beautiful as these sunsets appear - the air is toxic irritating eyes and causing respiratory problems. This is just the beginning as wildfire season as yet to begin in the US and Canada.
Rayleigh scattering causes the blue color of the daytime sky and the reddening of the Sun at sunset.
Here's how Rayleigh scattering works. When there are a lot of smoke particles in the air, they act as filters for sunlight by scattering shorter wavelengths such as blue, leaving longer wavelengths of the light spectrum (like orange and red) behind. The effect seems more intense at sunset because of distance. When the sun is at a lower angle in the sky, its light has to pass through more of the atmosphere, meaning (in this case) more smoke particles.
It’s not only smoke particles that create Rayleigh scattering. There are many other particles in the atmosphere, such as dust, smog and clouds, that can also contribute to the scattering of sunlight, which is why sunsets and sunrises are more vivid some days than others.
Solar Halos
On this day an unusual darkening of the daytime sky was observed over the New England states and parts of Canada. The primary cause of the event is believed to have been a combination of smoke from forest fires, a thick fog, and cloud cover. The darkness was so complete that candles were required from noon on. It did not disperse until the middle of the next night.
