Chemical tracers from ATREX rockets, as seen from Pennsylvania, were tracked by special cameras to help study winds in Earth's atmosphere.
" Five sounding rockets will launch from NASA's Wallops Flight Facility in Virginia releasing a chemical tracer into the air. The chemical – a substance called trimethyl aluminum (TMA) -- forms milky, white clouds that allow those on the ground to "see" the winds in space and track them with cameras. In addition, two of the rockets will have instrumented payloads to measure pressure and temperature in the atmosphere." - NASA