The rocket’s plume can create a long shadow on top of the clouds.
Tell you more about create this effect. Rocket Launches Can Create Night-Shining Clouds ... - NASA Rocket Above The Clouds (Sky Overlay)
Rocket launches have been shown to create these rare, ice-crystal-driven, night-shining clouds in the mesosphere, particularly when rocket exhaust is transported by high-altitude atmospheric tides. The rocket’s plume can create a long shadow
From above, the exhaust trail looks like a thin, razor-sharp line stretching upward. night-shining clouds in the mesosphere