T Matthew

When a Boeing 777 approaches in saturated air, the pressure changes around its wings can become visible as enormous ribbons of condensation, revealing the invisible aerodynamics at work. As air flows over the wings, pressure drops and its temperature can fall enough for water vapour to condense into visible droplets. Around the wingtips, the pressure difference between the upper and lower surfaces also drives powerful vortices, which can make the vapour twist into spectacular trails. The effect is especially striking during landing, when the aircraft is flying at lower speed with high-lift devices deployed to generate the lift needed for a controlled approach. What looks like smoke streaming from the aircraft is actually a temporary visualisation of airflow, pressure and humidity interacting around the airframe. For a few seconds, the atmosphere makes the invisible physics of flight visible.