Smoke particles have tinted the sky an unnatural shade.

The wildfires that have been consuming forests in the western United States have begun to affect more than towns and vegetation. On Wednesday, and continuing into today, cities in California, Washington, and Oregon experienced a skyline tinged a disconcerting shade of orange.

According to NASA scientists, the cause of this ominous sky is smoke particles being ejected from the wildfires. These particles clump together in the Earth’s atmosphere, partially blocking out the sun’s rays and altering how we see its color.

“The smoke particles from the fires allow sunlight’s longer wavelength colors like red and orange to get through while blocking the shorter wavelengths of yellow, blue and green,” a NASA rep explained. “Those longer wavelengths give the sky a red or orange tinted appearance. Similarly, during sunrise and sunset times when the sun is near the horizon, sunlight has to travel through more of Earth’s atmosphere to get to you. The additional atmosphere filters out the shorter wavelengths and allows the longer wavelengths to get through, providing reds and oranges during those times.”

Social media users have taken numerous pictures of the skyline, likening it to skylines seen in various shows and films like Avatar: The Last Airbender and Blade Runner 2049.

California has surpassed its previous wildfire record as firefighters continue to try and quench the flames. The intense heat of the flames and dryness of the forests has been attributed to global climate change. A large portion of California is under a Red Flag warning, while Oregon Governor Kate has declared an official wildfire emergency.

“We are living in a world that has been influenced by global warming, and we’re feeling the impacts,” said professor Noah Diffenbaugh of Stanford’s School of Earth, Energy, and Environmental Sciences.