American Airlines and Google were able to cut contrails made by jets by more than half during a small trial, a move that could significantly reduce the global-warming footprint of the travel industry, but with a slight increase to fuel use.
That doesn’t really explain how contrails themselves increase global warming. Is it that forming the contrail pulls energy out of the gaseous water (and onto control surfaces) via condensation so now the atmosphere can absorb a bit more heat while the GHG (water) remains in the air? How does using more fuel and outputting even more CO2+water+methane counterbalance that?
Contrails contribute to heating because they block light emmited from Earth’s surface from exiting the atmosphere. It is the same mechanism by which natural cloud cover contributes to heating.
During the day, the effect is largely neutral with respect to warming. Clouds will block some sunlight and block some reflected light, net effect is roughly zero. During nighttime, however, they only block the Earth’s surface radiation from discarding energy to soace and thereby act like a blanket, trapping heat. It is the reason why overcast nights do not cool as much from the day time high temperature.
Fun fact, the days after 9/11, where all US flights were grounded, had a 2-degree Celsius increase in the range of temperatures experienced from the daily high to nightly low compared to the surrounding days with normal levels of air travel.
How does that work? Expending more carbon (and thus more CO2 release I would think) to reduce how much water condenses on control surfaces?
it’s in the article. diverting around weather patterns where an AI said contrails were likely to form.
it’s hard to judge how real the result is. it’s early days.
That doesn’t really explain how contrails themselves increase global warming. Is it that forming the contrail pulls energy out of the gaseous water (and onto control surfaces) via condensation so now the atmosphere can absorb a bit more heat while the GHG (water) remains in the air? How does using more fuel and outputting even more CO2+water+methane counterbalance that?
Contrails contribute to heating because they block light emmited from Earth’s surface from exiting the atmosphere. It is the same mechanism by which natural cloud cover contributes to heating.
During the day, the effect is largely neutral with respect to warming. Clouds will block some sunlight and block some reflected light, net effect is roughly zero. During nighttime, however, they only block the Earth’s surface radiation from discarding energy to soace and thereby act like a blanket, trapping heat. It is the reason why overcast nights do not cool as much from the day time high temperature.
Fun fact, the days after 9/11, where all US flights were grounded, had a 2-degree Celsius increase in the range of temperatures experienced from the daily high to nightly low compared to the surrounding days with normal levels of air travel.
Some of the other comments have decent explanations.
where?
https://lemmy.ml/comment/2686472
Very helpful. Thank you!