John Davies

Contrail Cirrus 241, 18 May 2023

Cirrus Aviaticus

John Davies has been making B&W infrared photographs of the north sky above Liverpool and Lancashire in north west England since 2013. The span of each cloud photograph represents a distance of at least six miles across the sky.

These images are of the high-altitude cirrus clouds made of ice crystals. They focus specifically on the visible contrails (condensation trails) and contrail-induced cirrus clouds produced from jet engine exhaust fumes. These are mostly generated by commercial flights that typically cruise at six and a half miles above sea level.

Cirrus covers an average of 31.5% of the Earth's surface (CALIPSO satellite data). Increased air traffic has been implicated as one possible cause of the increasing amount of cirrus in Earth's atmosphere - contributing to climate change through Radiative Forcing*. Most all jet engines also emit substantial amounts of CO2 (carbon dioxide). At the global level CO2 is the most important greenhouse gas: the warming effect of CO2 emissions being long lasting and cumulative.

Scientific research suggests contrails and contrail cirrus clouds are the largest net warming component of aviation emissions. This impact needs to be considered alongside continuing CO2 mitigation strategies.
* The Radiative Forcing effect is where the balance is disrupted between radiation coming to the earth from the sun and heat emitted from the surface of the earth going out into space. Source: Imperial College London’s department of Environmental Engineering.
Other sources:

Royal Aeronautical Society - Contrails & Contrail Management paper, April 2023

>European Aviation Safety Agency

> GOV UK Department for Transport
Images may not be reproduced in any form or by any means without the permission of John Davies
Photo and material Copyright © John Davies 1976 - 2023