It is not extremely rare to see hints of purple in the sky, especially at sunrise or sunset. Certain atmospheric conditions can contribute to purple skies. While a vivid deep purple sky is unusual, many people have likely seen transient purple hues while looking at the horizon.
What Causes Purple Skies
The primary cause of purple skies is the scattering of light. As sunlight enters the atmosphere, shorter wavelengths like blue and violet scatter more easily than longer wavelengths like red and orange. This scattering is enhanced when there are more particles in the air.
Moisture, dust, smoke, and other particles increase the amount of scattering that occurs. As the sun rises or sets, its light has to pass through more atmosphere. Sunrises and sunsets often appear more reddish since the blue/violet light has been removed. But with enough scattering, some of the violet light remains, creating purple tones in the sky.
Certain weather conditions can contribute to purple skies:
- Very humid air causes moisture scattering that favors purple hues.
- Dust or smoke particles from volcanic eruptions scatter more violet light.
- Thin, high-altitude cirrus clouds can scatter the purple end of the spectrum.
- Rainbows showcase the entire visible spectrum, including violet shades.
In most cases, these purple colors are subtle and temporary. But under the right conditions, vibrant and distinctive purple skies can occur.
Famous Purple Sky Events
While not common, some remarkable purple skies have occurred throughout history:
- The Battle of Mortimer’s Cross: On the morning of February 2, 1461, the sky supposedly turned purple just before a battle in the Wars of the Roses. This phenomenon became part of a legendary story about the origins of the “Rose of Mortimer.”
- The Great Storm of 1780: Unusual purple and green skies were reported across New England on September 11, 1780. This strange sight coincided with an unusual dark day where the sun was obscured by smoke.
- The Battle of Isandlwana: Some accounts of this 1879 battle during the Anglo-Zulu War describe vivid purple clouds gathering before the fighting began. Similar colors have been seen in African skies during large dust storms.
- The Krakatoa Eruption: The enormous 1883 volcanic eruption of Krakatoa in Indonesia released massive plumes of ash and gases into the atmosphere. In the weeks after the eruption, unusually colorful sunsets and sunrises with purple, green, and orange were visible worldwide.
- The Battle of Morval: In 1916 during World War I, some soldiers fighting in France reported seeing vivid purple clouds streaked with red the night before this battle on the Somme.
While these stories may have mythic or legendary elements, they suggest purple skies do occasionally occur during major dust storms, volcanic activity, and other extreme events.
Where Purple Skies are Most Visible
Purple skies tend to be visible in certain parts of the world more than others. Areas prone to specific weather conditions and natural events see these colorful skies most frequently.
| Location | Contributing Factors |
|---|---|
| Indonesia | Frequent volcanic eruptions that release dust and ash |
| Sahara Desert Region | Large sandstorms and dust clouds |
| American Midwest | Severe thunderstorms and supercell systems |
| Northern India | Monsoon season and dense pollution |
| Andes Mountains | High elevation and thin air; proximity to volcanoes |
In these regions, the right combination of particles, clouds, and humidity occur more frequently to produce purple-hued skies. The unusual colors are often seen before or during major weather events.
Purple Skies in Art and Culture
While fleeting in nature, purple skies have inspired many creative works and performances:
- Vincent van Gogh’s painting The Starry Night uses exotic colors like purple and green to convey the night sky in an emotional and imaginative way.
- Don McLean’s song “Vincent” (also known as “Starry, Starry Night”) references van Gogh’s painting and its “swirling clouds in violet haze.”
- The covers of several Deep Purple albums feature purple-colored skies, including Machine Head, Made in Japan, and Come Taste the Band.
- In Hindu culture, purple is a sacred color associated with spirituality and mysticism. Purple dusk skies are said to have unique energy.
- The video game Skyrim uses aurora-like purple skies in the mythical realm of Sovngarde where souls go after death.
Purple skies symbolize the beauty, power, and mystery of nature. Their rarity makes them even more meaningful when they briefly come into view.
Photographing Purple Skies
Capturing images of purple skies takes timing, skill, and the right equipment:
- Be prepared – Keep your camera or phone ready to photograph colorful sunrises/sunsets. Being ready for the fast-changing light is key.
- Use RAW format – RAW images capture greater color depth and are easier to adjust for dramatic skies. JPEGs can look washed out in comparison.
- Bracket exposures – Take multiple shots at different exposures. It’s hard to capture a vivid purple sky without blowing out the foreground. Exposure blending can help overcome this.
- Try panoramas – Wide panoramic shots can better capture the scale and expanse of the entire sky. Use apps to easily stitch images together.
- Edit thoughtfully – Some post-processing can enhance the purple tones already present. But be careful not to create unnatural HDR effects.
With the right techniques, photographers can capture mesmerizing images of these rare purple skies to share with others.
Conclusion
Purple skies are an unusual but natural phenomenon caused by the interplay of light, particles, and weather conditions in the atmosphere. While vivid deep purple skies are rare globally, they occur more often in places prone to volcanic eruptions, sandstorms, and pollution. Purple sunrises and sunsets have inspired art and culture for centuries, and photographers still seek these special events to document their beauty and transience. So although purple skies are uncommon, they provide an opportunity to appreciate nature’s wonders in unexpected colors.
