Contrails create clouds

[Second Time Around]

From  article in The Conversation:

"When several planes fly in the same general area over the same period of time, the contrails can combine, leading to the formation of cirrus clouds, which can act like a blanket, holding in heat."

The article was entitled "Study finds rerouting of airplanes to reduce contrails not as expensive as thought." 

It seems as though a huge reduction in contrails is possible at minimal cost.

The original article is at https://techxplore.com/news/2024-03-rerouting-airplanes-contrails-expensive-thought.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

[Steve Ward]

Surely it's dependent on atmospheric conditions ... ?

I get the pretty much the same amount of air traffic here day in , day out.

Some days the sky remains clear blue barring tiny , short , quickly disappearing trails , and on others the sky is full of long standing , slowly dispersing trails.

[Second Time Around]

Yes, it does of course depend on atmospheric conditions.

I didn't quote the entire article but this extract is relevant:

".......used weather and satellite data to create software models and AI prediction tools to determine whether it was feasible to divert planes from airspace that would lead to contrail formation. They found that it appeared possible to reduce contrail formation by approximately 54%."

[Steve Ward]

Planes routes and more importantly fuel loads are carefully calculated , they're not going to start diverting them all over the place willy-nilly just to possibly reduce contrails that may or may not form in some location or other ... 😄

[Second Time Around]

Steve, if you read the entire article you'll see that:

".....reducing contrails by 73% would raise fuel costs by just 0.11% and overall operating costs by just 0.08%. They also noted that rerouting aircraft under such a scenario would only involve 14% of all flights."

[DaveL59]

 

[Second Time Around]

Fascinating video, Dave!

It's long, but it's basically saying the same as the article I quoted but goes into more detail.

[Carbon Brush]

Thank you for posting the article link. It is a much debated subject.

At home I have a good view of a major high altitude airway. On a good day I can see a contrail start west of Liverpool (over the sea) and follow it beyond my Nottinghamshire overhead.
I know where I start viewing by timing to overhead and assuming cruising speed, or more accurately using Flightradar 24 to track.
Most contrails dissipate in tens of seconds, maybe a minute or two. Though on a few days, they can persist much longer.
Then there is the question of dissipating beyond unaided eye view, and dissipating beyond heat retention.

Think back a few years to the aviation shutdown caused by the (very long unspellable name) volcano in Iceland.
We had a period of no commercial flying. I remember looking at the sky on more than one day after flying resumed, seeing contrails that were all but games of noughts and crosses in the sky!
It certainly made me think about how 'clear' our skies are.

[Second Time Around]

One point that the video mentioned was that planes often wouldn't have to change course, merely change their height.

It was made by a Lufthansa pilot and referred to the same AI research done by Google that the article referred to.

I remember the lack of contrails during the first part of lockdown.  IIRC it was here, or possibly on Cloudy Nights, where it was observed that both transparency and seeing were better then

[Carbon Brush]

A contrail comprises water, carbon dioxide and bits of soot. As the carbon residues are tiny particles how long is it before they fall to the ground?
While carbon is in the sky, it will seed cloud formation.. I'm sure someone somewhere knows about this effect.

I remember reading a long time ago about Australian farmers making daily reports on pan evaporation.
This was on the orders of the government. Agriculuture department maybe?
Something that started in the 19th century and continues today.
Sorry I don't have all the details.
The evaporation rate had gradually changed due to the sky being less transparent.
I took a quick look to see if I could find the article. But no luck.
Again someone may know more.