An orange sky can be caused by a few different things. The most common reasons for seeing orange skies are wildfires, dust storms, and sunsets. In some cases, orange skies may indicate air pollution as well. Understanding what causes orange skies can help you determine if there are any potential hazards or issues to be aware of.
Wildfires
One of the most common causes of orange skies is wildfire smoke. Large wildfires produce huge plumes of smoke that can spread for hundreds of miles. The smoke particles in the atmosphere scatter more of the longer, redder wavelengths of sunlight, causing the sky to take on an orange hue. The thicker the smoke, the more intense the orange coloration will appear. Orange skies caused by wildfire smoke indicate there are large fires burning nearby, even if the fires themselves cannot be seen. Breathing smoky air can irritate eyes and lungs, so people with respiratory issues may need to take precautions when skies turn orange from wildfire smoke.
Some of the largest wildfires that have created orange skies across wide areas include:
| Fire name | Year | Location | Area burned |
|---|---|---|---|
| Siberian wildfires | 2021 | Siberia, Russia | 18.16 million acres |
| Black Summer bushfires | 2019-2020 | Australia | 46 million acres |
| Camp Fire | 2018 | California, USA | 153,000 acres |
The smoke from these massive wildfires turned skies orange across huge regions, from cities to rural areas. When an orange sky is accompanied by a smoky smell or haze, wildfires are the most likely cause.
Dust storms
Another common natural phenomenon that can cause orange sky conditions is dust storms. Dust storms occur when strong winds lift large amounts of sand and dust particles into the air from dry regions with loose topsoil. As with smoke, airborne dust scatters light in a way that makes the sky look orange or brown. Dust storms are characterized by hazy, overcast conditions, reduced visibility, and poor air quality.
Major dust storm events that have led to orange skies include:
| Location | Year | Details |
|---|---|---|
| Sahara Desert | 2020 | Dust cloud 6000 miles wide travelled across Atlantic to Americas |
| Middle East | 2015 | Multiple days of orange skies from seasonal dust storms |
| Phoenix, AZ, USA | 2011 | 100-mile wide dust storm (“Haboob”) blocked out sun |
The largest dust storms can spread particulate matter high into the atmosphere and carry it vast distances. When an orange sky coincides with reduced visibility and dust coating surfaces, it is likely caused by a nearby dust storm.
Sunsets
Clear orange skies are also common at sunrise and sunset, even when there are no dust storms or wildfires present. This is because the daytime blue light from the sun scattering through air molecules gives way to longer, redder wavelengths of light at shallow sun angles. The orange hue comes from a mixing of the dominant reds and residual blues in the sky as the sun dips below the horizon.
Factors leading to more intense orange sunsets include:
| Factor | Effect on orange color |
|---|---|
| More particulates/pollution | More scattering of reds |
| Moisture/high humidity | Enhanced, vivid oranges |
| Cloud formations on horizon | Bright reflected colors |
When particulate matter is elevated or moisture is higher, an orange sunset can become deeper and more brilliant. Clear skies will also show the oranges clearly. Typical sunset times seeing enhanced orange hues are the 10-30 minutes around sunset.
Air pollution
Manmade air pollution can also be a contributor to orange colored skies under certain conditions. Smog, haze, and particulate matter from sources like factories, car exhaust, and construction can scatter light and create orange tones when concentration levels are high enough.
However, air pollution levels rarely get so extreme as to turn the whole sky orange on their own. More commonly, pollution just adds an orange tint when combined with low sun angles or other natural events. Chinese cities like Beijing and Delhi, India are among places where both air pollution levels and orange hazy skies are problems at times.
When an orange sky corresponds to known high pollution days but no fire or dust storm, pollution particles are likely intensifying the color.
Volcanic eruptions
While less common than the other causes, volcanic eruptions can also turn the sky orange.Similar to smoke and dust, volcanic ash particles suspended in the atmosphere scatter light. Volcanic gases like sulfur dioxide also form aerosols that scatter longer wavelengths.
Historic volcanic events that created orange skies as far as hundreds of miles away include:
| Volcano | Year | Location | Details |
|---|---|---|---|
| Mount St. Helens | 1980 | Washington, USA | Ash column reached 80,000 feet |
| El Chichon | 1982 | Mexico | Biggest aerosol clouds in satellite records |
| Mount Pinatubo | 1991 | Philippines | Ash circled entire planet in 15 days |
Volcanic activity can lead to prolonged periods of orange, hazy skies downwind. The orange color may also be accompanied by spectacular red sunsets in areas impacted by eruption gases and ash.
Fires and smokestacks
In addition to wildfires, orange skies can occasionally occur due to controlled fires or industrial pollution sources. Large prescribed burns set intentionally over extensive areas can create enough smoke to turn the sky orange regionally. Power plants, smelters, oil refineries and other industry with large plumes can also discolor skies orange if emissions and outputs are high.
During temperature inversions in urban areas, industrial stack pollution getting trapped close to the ground can lead to localized orange hazy skies as well. The orange color usually appears most prominently at sunrise/sunset when light passes through the pollution at a low angle.
When an orange sky corresponds with no natural dust or fire events, industrial stacks and urban areas are often the cause. The coloration tends to be localized rather than regional in these cases.
Astrophysical phenomena
Extremely rarely, astronomical phenomena beyond Earth can also be responsible for orange skies. Cosmic rays from a supernova or solar storms hitting Earth’s atmosphere could theoretically scatter light and create orange hue skies across an entire hemisphere.
However, occurrences like this have never been scientifically documented. Any contributions of supernovas or solar activity to orange skies are negligible compared to terrestrial dust and fire events.
Multiple contributing factors
There are often multiple contributing factors behind famously intense orange sky events. For example, the “Skies of Blood” seen worldwide after the 1883 Krakatoa volcanic eruption were likely a combination of volcanic ash and an ongoing El Nino raising background dust levels globally.
Likewise, orange skies in places like Singapore in September 2019 resulted from both Indonesian wildfire smoke and a tropical storm stirring up dust. When extreme orange skies occur, it is usually not the result of just one influence, but a combination of exceptional natural events coinciding.
Localized vs widespread phenomena
The geographic scope of an orange sky can provide clues to its cause. Localized orange glows are often the result of urban pollution or a singular prescribed fire, while regional or long-distance orange skies usually point to events like major wildfires, immense dust storms, or volcanic eruptions.
Widespread orange coloring visible from hundreds of miles away signifies incredibly large amounts of particulates high in the atmosphere, which narrows down the likely culprit to phenomena like volcanic eruptions. More contained orange skies suggest smaller scale pollution, fires, or dust storms in the immediate vicinity.
Health and safety precautions
When the sky takes on a thick, orange color, it often means there are significant particulates in the air that could impact health and safety:
| Issue | Precautions |
|---|---|
| Smoke inhalation | Stay indoors, use air filter |
| Reduced visibility | Avoid driving, adjust activities |
| Poor air quality | Wear protective mask outside |
Orange skies are a visual indicator that special care may need to be taken for respiratory issues, driving hazards, and other concerns related to smoke, dust, ash, and pollution. When skies turn orange, it is a sign to be vigilant and take measures to mitigate any health and safety impacts in the area.
Checking air quality reports
To confirm the specific causes behind an orange sky and potential health impacts, checking local air quality reports and forecasts can provide more detailed insights:
– Government agencies issue air quality health advisories explaining pollution, smoke, and dust scenarios when orange skies occur.
– Air quality sites like AirNow.gov provide current and forecasted air quality index readings for locations across the U.S.
– Local weather reports will highlight any regional dust storms, smoke transport, or other conditions contributing to orange skies.
By consulting multiple sources, people can determine if orange skies in their location warrant precautions and are due to wildfires, dust storms, pollution, volcanic activity or other causes.
Conclusion
Orange colored skies have a range of potential causes, from sunlight scattering through wildfire smoke and dust storm particulate matter to vivid sunsets. When skies turn orange, it visually signifies there are particles or pollution present in the air that could impact visibility, health, and activities. By considering the scope of discoloration, current weather conditions, and air quality data, people can determine the likely reasons behind orange skies in their area and take appropriate precautions if needed. While often signaling the presence of hazards like smoke inhalation, orange skies also reflect the forces of nature and light interacting in the atmosphere to produce vivid sunrises, sunsets, and storm events.
