These are anti-solar rays. They are occasionally/rarely visible in the sky opposite the Sun. The Sun must be low in the sky - less than 20 degrees above the horizon. The alternating dark and light bands are caused by shadows from clouds. Dark bands are shadows, the light bands are sunlight scattered by dust and water vapor in the atmosphere. Without the shadows there would be no banding, just the typical uniform scattering of light normally visible in the sky.
The photo above was taken near sunset and is looking east near Cedar Falls, Iowa. The setting Sun is behind the photographer. Notice how the bands appear to converge to a single point. This is an illusion. The rays are actually parallel. The same illusion is seen when looking into the distance along a railroad track or highway. The rails or roadway appear to converge to a point. The next time you watch a sunset - turn around. You might see anti-solar rays behind you.