Condensation trails – so-called contrails – are artificial clouds composed of water, soot, and cool air behind jet aircraft in the upper troposphere and lower stratosphere. These non-CO₂ emissions are responsible for a large share of aviation’s impact on climate change. A French-German research project is now aiming to observe and forecast their impact.

Contrails have been an object of research in the past years due to their warming effect and thus climate impact. They are mostly ice crystals: water vapor is already present in the atmosphere, and when extra vapor from an airplane exhaust rapidly saturates moist air, the water condenses and freezes. Observations of the formation of linear contrails and their spreading into contrail cirrus clouds show that contrails and contrail cirrus have a net positive warming effect. Large progress has been made on the modeling of the contrail formation, but uncertainties remain for the next hours.

Sky imager technology for contrail detection

A French-German consortium is now joining forces in the research project “CONTRAILS – Contrails in the Climate System: from Observation to Impact Modelling and Prediction”. The project aims to provide tools to monitor the impact of contrails on climate and to help support future experimental tests. As a joint work of the German Weather Service DWD (DE), Thalès Research & Technology (FR), Reuniwatt SAS (FR) and Laboratoire atmosphères, milieux, observations spatiales (FR), the CONTRAILS project develops and couples cutting edge trustworthy AI methods and physical models to improve the monitoring and characterisation of contrails by getting access to a better understanding of the entire physical process underlying their formation, and by augmenting models accordingly.

Each organisation member of this consortium will bring part of their expertise to successfully carry out the project.

Cloud observation using sky imagers

Reuniwatt is an expert in cloud observation and forecasting. Given this expertise, Reuniwatt will provide sky imagers for visible and infrared wavelengths for the CONTRAILS project, to allow a state-of-the-art assessment of contrails. Learn more about cloud observation and forecasts using our sky imagers.

We are proud to be on this joint research project, which will have operational applications in the aerospace industry. The monitoring of contrails’ impacts and the refining of contrails formation criteria used for the optimization of flight trajectories will help with future strategic choices for France and Germany. The project’s outputs will for example help better assess and plan the deployment of hydrogen engines to reduce the global climate impact of flights. Reuniwatt believes in innovation as a catalyst for technological advancements. If you want to get in touch with us regarding the project CONTRAILS, contact us!

About Reuniwatt (
Reuniwatt is a major player of the solar radiation and cloud cover assessment and forecasting. Based on solid Research and Development works, the company offers reliable products and services intended for professionals of various fields, making the best out of two key facets of the meteorology: atmospheric physics and data sciences. A particular focus has been placed on solar energy forecasting, while developing cutting edge solutions to improve the short-term prediction of the solar resource.
The company has won many grants, including H2020’s SME Phase 1 programme, which makes Reuniwatt a European Champion with regard to innovation. Reuniwatt has also been selected among the national fast-growing companies to join the prestigious French Tech 120 programme in 2020, and remains a part of the selection for 2021, and the French Space Tour 2021.