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2 months ago
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The skies over Florida turned an ominous purple moments before catastrophic Hurricane Milton made landfall Wednesday evening.
Described as 'mesmerizing' and 'unsettling' by locals, the first photos of the phenomenon were taken just hours before the Category 3 storm made landfall.
But purple skies were seen throughout the state - including in Palm Beach, Fort Myers and St. Petersburg - during and after the storm as well.
It may look like a filter, but this rare sight was produced entirely by nature.
This only happens when atmospheric conditions are just right, and tends to coincide with hurricanes or typhoons.
Florida residents have shared photos and videos of unusual, bright purple skies over the state as Hurricane Milton approached
'You don't necessarily have to have a tropical cyclone to see skies like that, just the right atmospheric conditions to allow the necessary amount of light scattering,' AccuWeather Meteorologist Brett Rossio has said.
The photos show cloudy, electric purple skies glowing at dusk. In some of the images, damage from the hurricane stands out against this strikingly beautiful backdrop.
To understand why stormy skies can display this purple hue, it's first important to understand how interactions between atmospheric particles and light create different colors.
The sun emits shortwave radiation on the visible light spectrum - the portion of the electromagnetic spectrum that the human eye can see.
When visible light particles reach Earth's atmosphere, they undergo a process known as Rayleigh scattering.
This is the scattering of light that occurs when radiation particles interact with atmospheric particles that are much smaller than them.
Shorter wavelengths of light - which include blues and purples on the visible light spectrum - scatter more easily than longer wavelengths.
'This is why the sky appears blue on a nice sunny day with the sun high in the sky,' Rossio said.
'Some of the ultraviolet rays make it to the surface, which leads to sunburn, and the oranges, reds and yellows on the spectrum are of the longwave variety and are not scattered, therefore they appear as visible white light.'
When visible light particles reach Earth's atmosphere, they undergo a process known as Rayleigh scattering
Shorter wavelengths of light - which include blues and purples on the visible light spectrum - scatter more easily than longer wavelengths
When the sun sets, the angle at which the light hits the atmosphere changes, which in turn changes the color of the sky to pinks, purples, oranges, reds and yellows.
But the purple skies seen before Hurricane Milton hit Florida weren't caused by the angle of the sun.
This spectacle was actually due to an increased amount of water vapor in the atmosphere from the storm.
More vapor means more particles, and having more particles in the atmosphere results in more scattering of light, Rossio explained.
When this scattering occurs around dusk, it can create a pink hue that is superimposed upon a dark blue sky above.
Increased water vapor in the atmosphere and the timing of Milton's approach created the perfect conditions to create these purple skies
Not all hurricanes produce purple skies, and trying to predict when it will occur is 'trying to forecast where a rainbow will occur,' Rossio said
'If you have the right angle, especially in the evening hours, the pink hue that is superimposed with the dark blue sky produces a purple,' Rossio said.
'This is often the case if you have low ceilings of stratocumulus clouds overhead in the eastern sky and clearing in the west,' he added.
Milton isn't the only hurricane to have produced electric purple skies.
Category 1 Hurricane Florence and Category 5 Hurricane Michael - both of which hit the US in 2018 - caused this effect.
Not all hurricanes produce purple skies, however. Trying to predict when it will occur is 'trying to forecast where a rainbow will occur,' Rossio said.
But Hurricane Milton rolled in at just the right time to bathe the sky in this unusual color.
