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The Skilled Interpretation of Weather Satellite Images: Learning to See Patterns and Not Just Cues
Published in Robert R. Hoffman, Arthur B. Markman, Interpreting Remote Sensing Imagery, 2019
Contrails (condensation trails or cirrus-type clouds formed by highflying jet aircraft) mark the highways in the sky that jet planes use. That is why so many of the trails parallel each other and you can see planes follow planes across the sky. If the contrails last for a long time, chances are the air at flight level was already moist; if the contrail disappears almost as fast as it forms, the air aloft is likely dry.
Aircraft emissions: gaseous and particulate
Published in Emily S. Nelson, Dhanireddy R. Reddy, Green Aviation: Reduction of Environmental Impact Through Aircraft Technology and Alternative Fuels, 2018
Contrails, or condensation trails, are clouds produced by aircraft engine exhaust. Of all aircraft emissions at altitude, those of interest for their effect on contrail formation are water vapor, sulfur gases, and fine particles. Water vapor increases humidity, and sulfur species contribute to the formation of small particles that can serve as sites for water droplet growth. When enough humidity is present in the engine exhaust plume, water condenses on small particulate matter, forming liquid droplets that quickly freeze as the exhaust air mixes with the colder ambient air. The resulting ice particles create a visible contrail. The humidity level depends on the external air temperature, the amount of water already present in the surrounding air, and the amount of water and heat emitted in the engine exhaust (EPA, 2000).
Emission-aware adjustable robust flight path planning with respect to fuel and contrail cost
Published in Transportmetrica B: Transport Dynamics, 2023
The current research focuses has shifted from business objectives to environmental objectives. Similar research work can be traced back to Williams, Noland, and Toumi (2002)’s work. Williams, Noland, and Toumi (2002) proposed a model to restrict the allowable cruise altitudes, which is able to minimise the creation of high-altitude contrails. Detwiler and Jackson (2002) explained that aerodynamic contrails are formed by hydrocarbon fuel-powered aircraft engines passing through airspace with sufficiently cold and humid atmosphere. Some young or newly formed contrails can spread out due to wind shear and form contrail cirrus (Kärcher 2018; Yin et al. 2018). Once they have formed and become persistent contrails, scientists believe that these contrails will have further impacts on climate change and the Earth’s atmosphere (Minnis et al. 2004). Teoh et al. (2020) believe that a minor 1.7% change in flight altitude can reduce 60% of contrail formation. It is worth noting that the price of fuel has dropped recently and airlines now will have more incentives to produce a flight path solution in the sense of social and cooperate responsibility to the environment (Edwards, Dixon-Hardy, and Wadud 2016). Various publications have considered the aviation operative emission and its environmental impacts in flight path planning model (Soler, Zou, and Hansen 2014; van Manen and Grewe 2019). However, the aforementioned publications only considered the contrail presence as a deterministic variable. One should note that the spatial meteorological condition is a seasonal factor and changes from time to time. Meanwhile, flight path planning is usually a tactical decision, where the decision must be made before a season. The connection between the data-driven model and uncertain factors in the tactical decision-making level is yet to be discussed.