April 17, 2016

Super Contrail Day

Today was not only 20F warmer than normal, but was accompanied by one of the most amazing contrail displays I have seen in long time.  Here is the NASA MODIS visible imagery for early this (Sunday) afternoon for off the U.S. West Coast.  You see all the thin lines?

Those are contrails produced by high-flying jet aircraft.

A blow-up of the section off the Oregon/WA border is below:

Why was this such a spectacular contrail day?  Because vast areas in the upper troposphere was at or near saturation (100% relative humidity).

Today there was a ridge of high pressure over the West Coast, as shown by the upper level map at 300 hPa (around 30,000 ft) at 11 AM.  \

This map shows that there was southwesterly flow over the eastern Pacific that was associated with warm advection (approach of warmer air) and lifting, which led to saturation.   To prove this, here is a 6-h forecast for 11 AM on Sunday showing relative humidity at 300 hPa (against around 30,000 ft).  The air is saturated (100% relative humidity) in the region of the contrails.

That is why a vast area was covered with patchy high ice crystal clouds (mainly cirrostratus).  The moisture from the jet engine combustion (plus the particles emitted from the burning fuel) helped thicken the cirrostratus, producing contrails.    Contrails are FAR less evident in dry air.

We can prove the upper troposphere was near saturation by viewing the vertical sounding (using a radiosonde, a balloon-lofted instrument package) this morning at Quillayate on the Washington coast (see below).  The red is temperature, the blue is dew point, and when they approach each other the air is close to saturation.   From 550 hPa to 200 hPa (roughly 17,000 ft to 40,000 ft) the air was saturated or close to it.    A little extra moisture ensures saturation and cloudiness.

Some folks believe that the contrails shown above are chemtrails, toxic chemicals emitted by a secret U.S. government program.  But such ideas have no basis in truth and the fact contrails are more frequent when the air is close to saturation is strong proof of the benign origin of contrails.

Interestingly, contrails WARM the planet.  They reflect some solar radiation to space, but their impact on the infrared radiation balance of the planet is larger (they intercept infrared radiation coming up from below, where it is warmer, and emit infrared radiation at a relatively cool temperature).


  1. The upper atmosphere today was much drier over here in the Spokane area.I noticed that contrails dissipated very rapidly,maybe lasting ten seconds at most.Suprising contrast,West vs East!

  2. You are amazing with these topics, I never know what to expect each time I come here.

  3. Way back in the mid-1990's I was at a science conference on global warming and was talking to a meterorologist. His comment was that contrails "could be" the reason for warming. Particularly, since warming appears to have been occurring at night, while daytime temperatures have not been increasing. Those are his comments, probably close, but not an exact quote.

    Your thoughts on this subject??

  4. Yuck. I hate those things. On days like we're now enjoying I love gazing up at a beautiful blue sky with the high, wispy clouds. Makes me feel peaceful and safe. And then along comes one or more aircraft, sometimes several in rapid succession, mucking up the lovely scene with contrails. I know some folks think they're pretty and that's okay. I'm not one of them. Not one iota of natural beauty. And here in Olympia, where we've lived for more than 25 years, it's painfully obvious the air traffic patterns have recently changed where I'm suddenly seeing several a day. What a disappointment.

    Yes, I've flown about as much as y'all have so I'm part of the "problem". I take responsibility for my own actions. But still, yuck.

    - p

  5. Hi Cliff,

    I would have thought the contrails would produce a net cooling by reflection of visible light... Whatever the human race does to the planet, it seems to be mostly bad...

  6. Yuck? It's a sign of technological progress and the fact that there are over 6 billion people on earth. It reminds me of how small the world really is. And whatever we do to the planet, it doesn't hurt it, it only hurts the viability of ourselves and other species. The earth will always be here, unless a giant asteroid hits it or the sun explodes. Keeping our world habitable for humans is the real drive behind "saving the earth".

  7. I, too, am disturbed by these "CHEMtrails" as they are loaded with chemicals that are making so many sick with lung conditions that I have never seen before. Many more with weakened immune systems and just not well overall.This has come since the Chemtrails have increased in number and frequency.
    I miss the blue skies!

  8. Today my two year old asked me, "Why are those sky writers making white rainbows?!" So delighted that I will be able to explain this to her tomorrow.

  9. I don't know if it was the climate at the time, or just the fact that I lived in the upper Midwest in the 1950's and first half of the 60's, but I loved the way the sky was so often decorated with vapor trails. Seemingly every day in summer. Sometimes they turned and twisted in tight circles as fighters and bombers practiced. As a kid, I thought that was cool to watch.

    In the 50's, the vapor trails were almost all jet bombers or the rare propellor plane that was flying very high. But that was nothing like pictures I've seen during the 1940's over Germany when the sky turned completely white from vapor trails from planes at war.

    Nowadays, its almost all commercial jets. That's a most comforting thought now that I've grown older and wiser.


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