View Full Version : Contrails og klima
Bluescan
01-02-2021, 19:26
Klima og fly er jo en kontinuerlig debatt, men som regel handler det om klimautslipp. Nå har Maastricht har kommet med en NOTAM som sier følgende:
IN AN EFFORT TO MINIMISE THE IMPACT OF AVIATION ON THE
ENVIROMNENT, MAASTRICHT UAC WILL BE RUNNING A CONTRAIL PREVENTION
TRIAL. FLIGHTS MAY BE TACTICALLY REQUESTED TO DEVIATE FROM THE
PLANNED/REQUESTED FLIGHT LEVEL BY THE SECTOR CONTROLLER.
ANY FLIGHT FLYING VIA MAASTRICHT UAC SECTORS MAY BE CHOSEN. THE TRIAL
WILL GO AHEAD DEPENDENT ON THE WEATHER CONDITIONS.
AD/FIR: EBBU
FROM: Mon 18 Jan 2021 15:00 TO: Sat 27 Mar 2021 05:00
SCHEDULE: 1500-0500
: NOTAM A/206/21
Så i korte trekk kan fly bli bedt om å endre høyde for å unngå å lage contrails. Er det noen som har noe kjenskap til dette prosjektet?
Det er for å få optimal spredning. I disse coronatider er det viktig å sette inn støtet der motstanden er størst.
;)
Her er en meget god artikkel som forklarer det hele :)
https://ops.group/blog/contrails-chemtrails-and-climate-change/
Litt på siden, men den begrensede trafikken det (snart) siste året har jo resultert i påfallende få contrails å skue mot.
Her er en meget god artikkel som forklarer det hele :)
https://ops.group/blog/contrails-chemtrails-and-climate-change/
Litt pussig måte å skrive det på. Er ikke vant til å tenke på det å få tildelt en annen level som en re-routing, og det er level som står i NOTAM. Noen ganger kan 1000 fot være nok til at man ikke lager contrails.
Spennede etter 9/11 der flytrafikken sto på bakken i ett par dager fant man liten effekt.
Since the 9/11 terrorist attacks, it has been widely believed that the pretty white lines in the sky created by aircraft at altitude - otherwise known as 'contrails' - are a significant contributor to global warming.
The theory goes that contrails can become cirrus clouds that trap 'outbound' longwave radiation (heat) from the Earth's surface and atmosphere. They do this better than they reflect 'inbound' solar radiation (sunlight) back into space, so their net effect is warming.
In order to prove this, you might use the 'diurnal temperature range' (DTR), which is the difference between peak daytime temperatures and minimum night-time temperatures. You would compare DTR when aircraft are flying, with DTR when they are not flying. If the range increased, that is, night-time got colder and daytime warmer, it would demonstrate that contrails were indeed trapping outbound heat and reflecting inbound sunshine.
The problem here is that air traffic never actually stops. But for three days after 9/11, that's exactly what happened when all commercial flights were grounded. A team led by David J Travis of the University of Wisconsin-Whitewater took the necessary measurements, crunched the data and published the findings in the journal Nature.
The result? DTR did indeed widen by a full 1°C during those three days, in distinct contrast to the three days before the grounding and the three days after flights resumed.
But now a US study by Dr Gang Hong of Texas A&M University has found that DTR variations of 1°C during September aren't all that unusual and that the change in 2001 was probably attributable to low cloud cover. Elsewhere, a team at Leeds University, working with the Met Office Hadley Centre, ran contrails through its climate models and found that you'd need about 200 times the quantity of flights over America to produce a significant effect on DTR.
So while climate warming contrails join endangered polar bears on the list of flawed factoids, it begs the question of why the idea gained so much traction. The three-day grounding was an unprecedented scientific opportunity, yes, but the sample size was arguably far too tiny to have ever produced anything but indicative findings and certainly nothing approaching definitive proof.https://www.bbc.co.uk/blogs/climatechange/2009/05/911_contrails_study_challenged.html
Klima og fly er jo en kontinuerlig debatt, men som regel handler det om klimautslipp. Nå har Maastricht har kommet med en NOTAM som sier følgende:
Så i korte trekk kan fly bli bedt om å endre høyde for å unngå å lage contrails. Er det noen som har noe kjenskap til dette prosjektet?
Projektet lyder lidt tosset måske, men der er gode tanker bag det. Ideen/teorien bag forsøget er, at contrails er en stor "contributing factor" mht. global opvarmning, og man vil prøve at se, om det er praktisk muligt at undgå de flight levels, hvor dannelsen af contrails er størst.
Du kan læse mere om forsøget her: [https://www.eurocontrol.int/publication/atm-contrail-mitigation-options-environmental-study]
Om det rent praktisk er muligt at udføre i normal travl sommertrafik er et større spørgsmål, men hvis man kan gøre en forskel noget af dagen, er det måske det værd. Naturligvis skal man også indregne faktorer som turbulens, øget brændstofforbrug etc. når man evaluerer. Så må vi i sidste ende finde ud af, om det mest var et show for at vise, at vi gør noget, eller om det rent faktisk gør en forskel.
Spennede etter 9/11 der flytrafikken sto på bakken i ett par dager fant man liten effekt.
https://www.bbc.co.uk/blogs/climatechange/2009/05/911_contrails_study_challenged.html
Skulle likt å vite hvor «Richard Cable» henter sine argumenter for at isbjørner i fare «are a flawed factoid».
I Flypoddens Flight 126 så snakket vi blant annet med Cicero, som forsker på dette
https://flypodden.no/2020/09/29/flight-126-contrails-not-chemtrails/
Foreløpige tester fra NASA og DLR tyder på at ved å bruke en 50:50 blanding av SAF (sustainable aviation fuel) med vanlig jetfuel, så mer enn halveres av contrails. Jeg var ikke klar over det, men visstnok fører renene forbrenning til mindre sot, og dermed mindre iskrystaller.
https://www.ainonline.com/aviation-news/business-aviation/2021-06-21/saf-lowers-contrail-formation-70-says-nasa
Besides lowering an aircraft’s carbon emissions, using a 50/50 sustainable aviation fuel (SAF) blend can also result in 50 to 70 percent fewer ice crystal contrails at cruising altitude, further reducing aviation’s impact on the environment, according to in-flight research by NASA and the German Aerospace Center (DLR)
Nyeste forsøk, sliter rett og slett med å kunne konkludere om contrails har en effekt eller ikke.
https://phys.org/news/2023-12-nasa-boeing-jet-contrails-science.html
NASA and Boeing chase jet contrails with science of climate impact in doubt