Lightning is a massive electrostatic discharge that occurs between electrically charged regions within clouds, the air, or the ground. The most common color of lightning is white or bluish-white. However, lightning can also occur in a wide range of colors depending on the chemical composition of the air and particles present. Some of the rarest lightning colors include red, green, pink, yellow, purple, and orange.
How lightning forms
Lightning forms through a process called electrification. Within storm clouds, wind and moisture movements cause charge separation. The rising and sinking air masses within the clouds cause positive and negative charges to accumulate at the top and bottom of the cloud respectively. The negative charges at the bottom of the cloud induce positive charges on the ground or objects below. When the built-up positive and negative charges become too strong, lightning is discharged between them to neutralize the difference in an explosive burst of energy.
The transfer of electrons during the lightning discharge causes the air surrounding the discharge channel to gain energy and emit light. The color of this emitted light depends on the chemical composition and energy state of the gases that make up the air. Normal air is composed primarily of nitrogen and oxygen which emit a white/blue light when excited. However, the introduction of trace elements from dust, pollution, and water vapor can impart different colors.
What causes rare lightning colors?
Here are some of the common causes of rare lightning colors:
Red
Red lightning is caused by the presence of nitrogen dioxide in the atmosphere. Nitrogen dioxide is formed when lightning reacts with air pollution from automobile exhaust and power plants. The nitrogen dioxide molecules emit a deep red light when excited by the lightning discharge.
Green
Green lightning is caused by the presence of oxygen in the atmosphere. During powerful positive lightning discharges, the electrical energy is strong enough to excite oxygen molecules which normally emit a greenish light. Aurora borealis (northern lights) also emit green light from oxygen atoms high in the atmosphere.
Pink
Pink lightning is caused by the combination of red nitrogen dioxide and blue/white excited nitrogen and oxygen. The mixture of the red and bluish-white light gives the lightning a pinkish hue.
Yellow
Yellow lightning is caused by the presence of desert dust and sediments in the air. Iron and other metals from soil particles emit a yellow light when superheated by a lightning discharge. Yellow lightning is most often seen in desert regions with lots of suspended dust.
Purple
Purple lightning is caused by the presence of ionized oxygen and nitrogen reacting with the discharge. The mixture of blue and pink light from these excited particles gives the lightning a purplish color.
Orange
Orange lightning is caused by the presence of methane. In swampy areas, methane gas emitted from decaying organic matter can interact with the lightning discharge to emit an orange glow.
Factors that influence rare lightning colors
Some factors that can influence the occurrence of rare lightning colors include:
- Air pollution – Nitrogen dioxide from automobile exhaust increases red lightning.
- Dust particles – Iron-rich soil dust creates yellow lightning.
- Atmospheric gases – High oxygen levels produce green lightning.
- Methane presence – Swamp gas leads to orange lightning.
- Cloud height – Tall thunderstorms alter air composition.
- Lightning strength – More energetic bolts excite atmospheric particles.
- Temperature/humidity – Affects air density and gas mixing.
Areas with lots of air pollution, dust storms, forest fires, and swamplands tend to have a higher occurrence of rare lightning colors. Powerful updrafts within severe thunderstorms also bring up air from different elevations that can influence the color.
Where rare lightning is most often observed
Some locations around the world where rare colored lightning is most frequently observed include:
- Northeastern United States – High population density produces lots of nitrogen dioxide pollution for red lightning.
- Central Africa – Lots of dust from the Sahara Desert produces yellow and orange lightning.
- Venezuela – Swampy conditions combined with heat and humidity produce orange lightning.
- Northern Canada – Aurora-type green lightning is seen in the northern latitudes.
- Central Plains, United States – Most prolific region for pink lightning.
In general, areas with lots of air pollution, dust storms, forest fires, and wetland environments tend to have the highest incidences of rare colored lightning.
When rare lightning colors are most common
Some times of year when rare colored lightning is most likely to occur:
- Summer – More intense thunderstorms produce strong discharges.
- Evenings/Night – Cooling air condenses and traps dust and pollution.
- After rainfalls – Moisture brings gases and particles into atmosphere.
- Early winter – First storms mix lots of accumulated gases and dust.
The most active and powerful thunderstorms tending to take place during summer months means rare colored lightning is more common in summer. Accumulation of dust, pollution, and gases during dry periods followed by mixing during storm fronts also leads to more varied lightning colors during transition seasons.
Observing and photographing rare lightning
Some tips for observing and photographing rare colored lightning:
- Monitor weather forecasts for intense storms in target areas.
- Set up a camera with a long exposure and wide aperture.
- Capture lots of shots to increase chances of catching a rare event.
- Use filters to reduce overexposure from bright strikes.
- Focus on cloud-to-ground lightning for most vivid colors.
- Composite multiple shorter exposures to create ideal image.
Photographing lightning requires patience and persistence. Combining a fast camera with manual setting adjustments and post-processing techniques can help capture those brief and brilliant bursts of colored lightning.
Interesting facts about colored lightning
- Red sprites and blue jets are types of colored lightning that occur above thunderstorms.
- Green and blue lightning have been observed on Jupiter, Venus, and Saturn.
- A form of dark lightning produces X-rays and gamma radiation.
- Volcanic eruptions and forest fires can also generate lightning-like electrical discharges.
- Lightning strikes the earth over 8 million times per day globally.
Lightning takes on amazing forms throughout our solar system and the universe. Even here on Earth, there are many interesting types yet to be fully understood including dark lightning and upper atmospheric electrical discharges.
Conclusion
While white lightning may be the norm, the rare bursts of colored lightning provide an awesome display of nature’s electrical power. The colors are caused by the interaction of the immense energy release with gases, dust, and pollutants in the atmosphere. Understanding the environmental conditions that generate these colors can allow us to predict locales and times where rare lightning may be observed. With patience and the right photography equipment, capturing images of these fleeting moments is an exceptional reward.
