23 replies to this topic

[Jackone]

Contrail investigation

Advertised in R Met Soc Weather February 2011

OPAL (Open Air Learning) is looking for folk to report contrails through March-May 2011.

For more information about this and how to join go to http://www.opalexplo...g/climatesurvey

The research may help to decide if contrails are a factor in global warming and if so an idea by how much.

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John Holmes has asked me to put this in here, please give feedback if possible.

[Gray-Wolf]

There is no doubt they hammer temps locally.....they're the bain of some summer days around here as we sit under the U.S. flightpath (on their way up to Lockerby before heading out across the Atlantic) so if the upper are conducive to condensation we end up with thick stripes covering the 11 O'clock to 1 o'clock position ruining North south.

On a bad day the European traffic heading back back to M/cr airport paint stripes in at 90 degrees to the 'upper' tracks completing the picture!

[legritter]

as an EX fellow of R M SOCIETY i am very interested in contrails . i wish i had kept a log of the times i have observed , sometimes a big proportion of the sky covered . i can remember about 4 yrs ago probably late spring just after dawn when the north american traffic starts to pass over , i counted aprox 25 30 contrails . i had just been star gazing , and i can vouch for the sky being completely clear . but what amazed me was after an hour or so these con trails spread out covering a big percentage of the sky , also what appeared like small clouds turrets and other shapes formed either above or mixed in with these contrails . odviously it all depends on upper level winds ,temp etc etc elevation of sun . but this would make a good and interesting study ,SO COUNT ME IN . I QUITE OFTEN SEE HIGH LEVEL JETS FLYING into THEIR OWN SHADOW WHEN THE SUN IS AT THE CORRECT ANGLE ,i am refering to the shadow of the contrail . i wonder if a jet making a DISTRAIL would affect things ,after all nature as produced that cloud , and along comes MR LONG HAUL AND BURNS A PATH THROUGH ALL THAT MOISTURE . all very interesting . regards LEGRITTER WINSCOMBE .

[Gray-Wolf]

" Near the day of purification there will be cobwebs spun back and forth in the sky"

Translation of the 'Hopi' Prophesies.......

[Weather Ship]

NASA have been running something similar for some time.

http://science-edu.l...nasa.gov/GLOBE/

[Village]

Too much is made of contrails.

Its not true that they ruin temperatures because when they can be suported in the environment, that environment at altitude moves and therefore so does any effect. Further they act to warm the environment at night , not cool it.

Lastly, and most importantly, contrails cannot exist on most days because the environment doesnt support them. Aircraft must be in an environment which is moist enough to support condensation otherwise they immediately and very rappidly evapourate to leave a clear sky again.

Aircraft by chance must be at the exact altitude of any moisture, if any. Thats why most days there are none existing.

Also, if there is a great deal of cloud at lower levels then any contrails that do exist have no effect at the surface whatsoever.

This is why the effects of contrails are greatly exagerated IMO.

[Weather Ship]

Just taking your last point, purely as a matter of interest. If you have veil of Cs at 30, 000ft and 8/8 of St at 1000ft are you saying the Cs will have no effect on the surface whatsoever because of the lower cloud?

[Summer of 95]

I've signed up to that site, and will post updates- starting with Tuesday morning when half the sky was covered in aircraft-induced haze that the sun could barely penetrate. Wednesday we've had a respite.

I've noticed increasing contrails for 10-15 years or so (those spreading types were non-existent or very rare before the late 1990s; I only remember seeing the short-lived ones when I was younger); and since last April's window of clear skies I've realised that a lot of what looks like Ci and Cs nowadays is actually aircraft pollution. (Has anyone else noticed how you hardly ever see those "mare's tail" cirrus formations against a blue sky anymore?) Also it's clear from satellite images that contrail pollution can travel, with locations far away from flight corridors losing sunshine too- some of the aircraft-induced haze that often ruins the midday sun here appears to have originated over the mid-Atlantic, and our planes' pollution deprives people in Denmark of a clear day.

Much of this stuff about the environment and climate change I'm not totally convinced by (I would happily bulldoze every wind farm ever built), but since Eyjafjallajokull I've been 100% certain that contrails need to be exterminated ASAP. Every time I see one of those newspaper articles about how children don't get enough Vitamin D because they're indoors too much, I wonder how much more they'd get without contrails blocking the sunlight. Aircraft-induced rickets; the industrial disease of the 21st century?

[4wd]

I'm sure you could find more evidence that contrails affect temperatures than CO2.
In the Spring especially, the reduced solar energy hitting the ground seems to noticeably cause lower temperature at ground level some days.
Overnight the effect probably reduces radiation heat loss.
We only 'notice' them on rare-ish clear days but there must be also be many days when they are there above a natural cloud layer too.

[pottyprof]

Just received my survey packs this morning. The packs contain everything you need to take part apart from some bubble mixture if you're going to take part in all four activities.

Something for the kids to do during Easter break.......

[Weather Ship]

4wd, on 03 March 2011 - 07:51 , said:

I'm sure you could find more evidence that contrails affect temperatures than CO2.
In the Spring especially, the reduced solar energy hitting the ground seems to noticeably cause lower temperature at ground level some days.
Overnight the effect probably reduces radiation heat loss.
We only 'notice' them on rare-ish clear days but there must be also be many days when they are there above a natural cloud layer too.

Sept. 11, 2001 presented a unique opportunity to study what the sky looked like without airplanes and contrails. In the wake of the 9-11 terrorist attacks, the FAA prohibited commercial aviation over the United States for three days. That's when David Travis, an atmospheric scientist at the University of Wisconsin, Whitewater, thought to look at how temperatures might differ at temperature stations around the country.

http://facstaff.uww....epapermar04.pdf

[barrel1234]

Is it just me or do contrails almost always only start forming mid morning onwards and into the afternoon, I never seem to notice them at first light, or is it just a case of air traffic times?

[Weather Ship]

barrel1234, on 04 March 2011 - 17:36 , said:

Is it just me or do contrails almost always only start forming mid morning onwards and into the afternoon, I never seem to notice them at first light, or is it just a case of air traffic times?

I suspect the latter because I've observed them at first light and they are only dependant on atmospheric conditions. So time isn't a factor.

[johnholmes]

Contrails need the right upper air conditions, somewhere in the Guides I think I posted about how that can be deduced from a skew-t or tephi diagram.
The other requirement is to have aircraft around in the area that is conducive to them forming. So those under the airways, have a google into the Civil Aviation web site to fond them, will see the most. Contrary to most thoughts its civil aircraft that make the most, military aircraft do make them but fighter aircraft over the UK are only at high level for short spells as their main area of practice for any war scenario is low level, hence the complaints about noise for the areas they use for this.
Aircraft from the north America tend to be at their most frequent early morning, say 0500-0900 GMT, west bound from east of the UK are usually more frequent in mid afternoon onwards.
below is an airways map I eventually found, somewhere is a full CAA one but not found it yet but it shows the main airways.



and below in pdf format is the item about how they are formed etc
 Contrails and forecasting them.pdf   754.83K   16 downloads
jh

Edited by johnholmes, 05 March 2011 - 12:26 .

[Village]

weather ship, on 01 March 2011 - 17:06 , said:

Just taking your last point, purely as a matter of interest. If you have veil of Cs at 30, 000ft and 8/8 of St at 1000ft are you saying the Cs will have no effect on the surface whatsoever because of the lower cloud?

What I said was that too much is made of the effects of contrails for the reasons I stated.
Contrails are most common in the mid lattitudes where there exists a sustained moisture injection at altitude (ie like a warm front scenario) for instance like your scenario ahead of an advancing warm front.

For most of the year the sun glances the atmosphere at such an angle in the mid lattitudes that even if an effect of a contrail shaddow on stratus way beneath it could be measured ( which they cannot) then the effects would be virtually undetectable at the surface.

Its simply not significant enough and that is the reason why scientists are asking for thousands of volunteers, simply just to find out if they can detect anything detectable whatsoever.

[Village]

Summer of 95, on 03 March 2011 - 00:57 , said:

I've signed up to that site, and will post updates- starting with Tuesday morning when half the sky was covered in aircraft-induced haze that the sun could barely penetrate. Wednesday we've had a respite.

Much of this stuff about the environment and climate change I'm not totally convinced by (I would happily bulldoze every wind farm ever built), but since Eyjafjallajokull I've been 100% certain that contrails need to be exterminated ASAP. Every time I see one of those newspaper articles about how children don't get enough Vitamin D because they're indoors too much, I wonder how much more they'd get without contrails blocking the sunlight. Aircraft-induced rickets; the industrial disease of the 21st century?

Hi Summer!

I wouldnt get too concerned about contrails because of the latest fad about vitamin D deficiency. These reports blow hot and cold. It was only a few years ago that the surveys returned that we should be keeping out of the sun and putting hats on kids and keeping them in the shade. Now the fad is that they need more sunshine.
Its the same with global warming theoretics....all the talk before was about the planet overheating because of us and now they find that possibly our contrails are acting to cool the planet....really? So what are we doing? in fact, are we significant enough to make any difference either way? I guess it depends on the latest report again.

[Village]

Contrails can be eliminated very easilly anyway. The aircraft will simply fly in the Stratosphere at 50,000 plus feet in the future where there is absolutely hardly any moisture and any injection of condensation will evaporate into the environment in a nanosecond.
Simples

[Pennine Ten Foot Drifts]

Talking of contrails, they can actually provide some quite pretty scenes:



Though how much of an effect this density of contrails might/might not have on the wider environment is beyond me.

Edited by Pennine Ten Foot Drifts, 08 March 2011 - 12:53 .

[ElectricSnowStorm]

This effect from an aircrafts exhaust pipes does reduce sunshine warmth, during summer it does help on hot days but ruins what could be a clearer day, these contrails then widen, spreading and joining into an almost altostratus layer of cloud, we also has distrails which cut holes out of cloud, ive also seen plain shadows, a light refractive optical phenomenon!(think thats it!)

[Gray-Wolf]

Has anyone , in my area , noted a reduction in low flying air traffic over the past 5 days? I'm not seeing either Leeds/Bradford's traffic or continental traffic for M/cr on it's descent into M/cr?

Am I being less than observant here? all the departure boards seem normal but ,like last years ash plume groundings, we have the silence that the lack of engine whine brings.