Aviation Carbon Footprints Red Herrings? (Are Contrails Green?) - Clouds are Blankets

peterbaker

As the cooler weather approaches those of us that use aviation may have noticed the sometimes fascinating spectacle of aircraft contrails at high altitude.

I am more guilty than most in condoning this form of travel, and I do it because it is apparently moneysaving to me individually.

So what have high altitude contrails to do with guilt? Is there a hidden cost in these which isn't receiving attention?

If you regularly use low cost services out of airports like Stansted, you eventually realise that the airport does almost sleep between about 01 and 05 in the morning and on the following (almost?) virgin crisp blue sky morning the planes don't get up in numbers until around 07. By 08, irrespective of the weather nearer the ground, the blue sky over the crossroads of near Europe (Amsterdam for example) is already criss-crossed with high altitude contrails. The jetstreams often attack them immediately and can create fantastic patterns ... I saw some the other day that looked like a cross between discarded umbilical cords, and strands of DNA :cool: . Others which were obviously crosswind contrails were quickly broadened into whispy narrow lenticular like clouds.

At those particularly busy crossroads where airways intersect, there was a latticework effect which seemed to be quickly filling in, much like the artificial lattices that surgeons apply over wounds to encourage congealing and healing.


These effects can sometimes be seen happening at more than one level. For example, I know it seems a bit high for clouds, but I think I saw a lot of contrails forming clouds up around 35 - 38,000 feet (that's about as high as a typical full loco jet goes most days, and where many of them aim to cruise in order to burn the least tonnes of carbon). But I could see what I thought might be evidence of similar thin clouds (perhaps even clouds made from contrails hundreds of miles away yesterday??) but at lower levels, some of them having apparently drifted to positions where they were 'filling-in' the 'valleys' in the more substantial 'normal' cumulus clouds at lower levels.

Sometimes there are a number of distinct layers of such clouds.

Now we all know that the more layers we wear on a chilly day, the warmer we will become. So it is with global warming and cloud layers I think.

I learned years ago of aviation cloud-seeding experiments. I think it is generally understood that without injecting anything else, simple contrails can seed clouds, but years ago, there were far fewer airliners and they flew at substantially lower average altitudes so the effects seemed negligible. Now I am not so sure.

I personally now wonder if we haven't now created an aviation industry which seeds as many clouds some days as God Almighty himself.

Are we costing ourselves dear tomorrow in even bigger ways than we are told?

richardw

What has this go to do with money saving?

I suggest you stay near home and pop to the library for a good read.

peterbaker

Interesting you should feel disposed to dismiss this so quickly richardw ... touched an aviation nerve, have I? Read my last line. That's what it has to do with moneysaving. Alternatively, moneysavers might wish to be alerted to the absolutely fantastic scenery that can be viewed from the comfort of their 1p seats!

I do not understand what idea has prompted your suggestion. Have I missed something?

angel

I missed the point on a documentary a couple of weeks back as I wasn't listening properly but someone was referring to how the climate changed in the US immmediately after the WTC bombings when all air traffic was stopped. I wish that I'd been listening more closely as I found that facinating, maybe a bit of googling might turn something up about it.

peterbaker

Yes you've reminded me now angel, I caught a glimpse of some such tv report about beautifully clear skies in the days immediately after 9/11 too ...

angel

Here we are, a bit of pre-bedtime Googling!!

http://www.airapparent.ca/library/full_text/911_study.htm

peterbaker

Thanks again angel ... your Googling was more successful than mine - I gave up on my first hit which was some whacky website that asserted that the US military were using contrails to spray us with bromide to protect us from terrorist anthrax attacks:eek:

But back on a serious note, it would be very interesting to be able to estimate typical insulation effects of contrail-induced overcast a bit more accurately.

The report you found suggested an immediate effect on the high and low temperatures in a 24 hour period was noticeable when air traffic over the US was grounded.

Following my nose from your link, and from the same original source, I have now found more detail here: http://www.pbs.org/wgbh/nova/sun/contrail.html

As contrails coalescing into cloud overcast is such a visible effect some days, it somehow looks much more significant in warming terms than the "aviation accounts for just 2% of worldwide CO2 emissions" propoganda that we have all been coerced into learning parrot-fashion in the last 12-24 months, doesn't it?

Question is, is it?