December 25, 2016

Holiday Air Quality

Generally, air quality is very good over western Washington due to the long over-water trajectory of air reaching our shores, but today there is a modest degradation (yellow colors) over some of the most populated areas (see graphic).  Why?  Lots of folks like to rev up their fireplace or wood stove for the holiday, and with cold air at low levels and high pressure aloft,  a layer of stable air is found aloft.

This stable air is indicated by a layer from roughly 50-m to 300 m aloft over Seattle where temperatures stay the same or warming a bit with height (inversion).
As noted above,  our air quality is relatively good because winds in the midlatitudes are from the west and thus our air comes over the vast Pacific Ocean--although a small amount of Asian air pollution does get across.    To illustrate our source of air today, below are backwards air trajectories (paths of air in space) for air parcels ending near the surface, 500 m aloft, and 1500 m aloft from the wonderful NOAA Hysplit system.  At all levels, our air came from the north Pacific, with the air parcels rising from near the surface to around 7000 ft before descending again over us.

A summary of air quality in Seattle  for the past year is summarized below (green is good air quality as shown in the legend above).  Mostly green (good quality) with a sprinkle of yellow (moderate) days like today.

The same plot for Los Angeles show many more moderate days and occasional poor air quality periods (dark orange).   Beijing would be orange or red nearly all the time.
I have a visitor from Beijing and she is impressed with the wonderful quality of our air.  Something to be thankful of.  U.S. air quality improved substantially starting in  the mid-70s  due to a bipartisan national program to clean-up our air (e.g., U.S. Clean Air Act, EPA, etc.).  If only we could be wise enough to foster a bipartisan effort to deal with increasing levels of greenhouse gases.


  1. Nice article, Cliff. I think any positive environmental advances will come to a screeching halt on January 20th, 2017. I don't see a soul in the new administration that has any interest in that whatsoever.

  2. One of the weirder aspects of living here after spending five decades in a place like Chicago is the prevalence of so many wood - burning fireplaces. It's a serious case of cognitive dissonance, where many pride themselves on being green 24/7 and giving thanks to mother Gaia, then go pollute the air with smoke. Most cities have had bans on all wood burning for decades, yet around here it's A - OK. What?

  3. Let's not forget wood is a renewable energy resource.

    Most importantly, wood is part of the active carbon cycle. It will release it's carbon whether you burn it for energy or let it rot on the forest floor, just the same over time.

    The majority of electricity in this country is very dirty. So are those "clean burning" fracked hydrocarbon gasses which contribute to our atmospheric carbon problem ie.. climate change!

    Those burning properly seasoned wood in efficient modern woodstoves are using top three most "green" energy source we have. Only solar or wind is with less impact.

    Remember, all fossile fuels are burning sequestered carbon, which is the root source of our crisis!

    So... That natural gas may seem clean in your city, but it is not. Just because the nasty side of production is not in your back yard does not make it cleaner than wood, and for sure burning sequestered hydrocarbons is the reason for our atmospheric carbon problem.

    We all need to think about where the energy for our heat comes from, and what we can do to reduce consumption, with fewer, smaller and better placed triple pane windows, smaller square foot homes and the latest insulation technology.

    Happy solstice!

  4. After growing up in Michigan and living in Colorado for 20+ years, I associate the smell of wood smoke with winter (I was fortunate to never be downwind of a forest fire). It's a very pleasant memory which hasn't dimmed now that I'm living out on the Oly Pen.

    This remains the scent of winter for those of us living in forested land. Wood smoke on a cold night is the smell of warmth and coziness.
    The old adage about the way wood warms you twice is still true. Once when cutting and splitting it, and again when you burn it.

    And yes, I still burn wood in the winter. Trick is to not live near cities or in places where there are winter inversions.

  5. Long-time, first-time. Love your blog and book, both of which I recommend to anyone who expresses even a slight interest in the weather (most of which seem to be transplants like me).

    Quick quest please--in the first graphic what do the grey dots stand for? It's not represented in in the second graphic/key.

    @Eric Blair--are you related to George Orwell per chance (Orwell was a nom de plume)?

  6. CLiff---you are not wrong.. However until countries like China and India ( still called "developing countries' but the U. N.... developing?--their pretty developed!) control their air, things are not going to get a lot better globally. Like everything its all about the $$.. really.. and that goes for both sides.

  7. Organic Farmer - you should be here during one of the frequent winter inversions - usually there are air quality warnings posted around Portland at those times. And keep in mind, that's in the dead of winter. You don't have those problems with natural gas, despite your protestations to the contrary.

    1. A conundrum indeed!

      I here what you are saying about woodsmoke in populated areas with inversion.

      It is imparitve we break our hydrocarbon addiction soon though, and biofuel energy is quite viable in many situations.


      Cliff looks like it is going to get quite cold again next week!?

  8. Softchoice - regarding my relation to Eric Blair; I wish. He's one of my favorite authors and writers from the 20th Century, and I believe his warnings are still very much relevant and at times often prophetic. I use his example of the current thought - crime and speak - crime that I see constantly in the media and in our culture at large. Anyone deviating from the current mindset is immediately smeared and shamed, a person to be driven as an outcast from society forevermore.

  9. Gray is "no data". Check out the original here:

  10. And yes, I don't call it firewood, it's biofuel. As a friend said long ago: "I don't have oil wells in my back yard". And I don't use it if there's an inversion and an Air Quality Alert.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

More Typical Spring Temperatures Will Save Washington and California's Cherry Crop this Year

Last year was a cherry disaster for the West Coast and the key driver was the cool/wet weather late last winter and spring in California.   ...