VISIBLE CONTRAIL FORMATION FROM FUELS WITH DIFFERENT SULFUR CONTENTS

As a test for postulated influences of sulfur emissions on nucleation, the contrail formation from a two-engine jet aircraft was investigate d using fuels with different sulfur contents for the two engines durin g the same flight. The sulfur mass fractions in the fuels were about 2 and 250 ppm, respectively, typical for aviation fuels. Other engine a nd fuel parameters were about the same for both engines. Contrail form ation was observed visually from distances as close as 100 m and docum ented by video and photos. The flight took place at 302 hPa (9 km alti tude), at ambient temperatures of about -50 degrees C, and relative hu midity for liquid water of about 34 %. Short contrails formed about 30 m after the engines. No visible differences were detected in the cont rails forming from the two engines. The observed conditions for contra il formation are close to those predicted by Appleman [1953] if the pr opulsion efficiency of the aircraft/engine combination during flight i s taken into account.