On October 10, 2024, Boulder experienced a stunning aurora borealis due to a strong solar storm that impacted the Earth’s magnetic field. This image, captured at 8:37 PM with my S24 phone camera, shows the northern sky behind the engineering center in Business field. The vivid colors in the sky, including reds and purples, resulted from charged particles from the Sun interacting with gases in the Earth’s atmosphere, particularly oxygen at higher altitudes, which is responsible for the red hues.

The solar storm that caused this phenomenon began with a coronal mass ejection (CME) from the Sun on October 8, 2024, which traveled toward Earth and struck two days later. The National Oceanic and Atmospheric Administration (NOAA) classified the storm as a significant geomagnetic event. Auroras were visible much farther south than usual, delighting spectators across Colorado, including in Boulder. The rare red and purple shades, seen in your image, are less common than the green auroras and occur due to high-altitude particles​

Regarding the clouds in the image, they appear illuminated by city lights from Boulder, a typical effect in night sky photography in urban environments. The dynamic interplay between the natural aurora light and the artificial light from below created this visually striking contrast. i think they r to be altocumulus clouds.