Smoke Vacation! Sept. 23, 2014

Yesterday late afternoon - the ground-level smoke had cleared somewhat

I took this picture to show the charming old sawdust-burner, from when this was a lumbermill, all grown-over with a vine. It's turning color at the top - not sure if too much sun/too little water, or fall color. And also to show the exaggerated atmospheric perspective given by the smoky low visibility.

The last time we were having smoke for weeks on end, from over a 1000 fires* caused by one set of lightning storms, I was wondering just how smoky it was in Renaissance Italy, when artists discovered the idea of atmospheric perspective. (How things get fuzzier, lighter, and bluer with distance, caused by more atmosphere between us and them with more distance.)

This was about noon today!

Today visibility is much lower; that further hill which just showed yesterday is gone today. (Maybe just a ghost there.) Normally, I think I remember, there's another hill or two to see...

And the air smells much smokier. So glad I had a chance to open up the house for a while yesterday evening to air out - my rooms had been closed up for 3 days - and even more glad that I was awake in the middle of the night to close it all up again, including the floor which was open before.

*This time it's one giant fire to our Southeast. It's West and Southwest of Lake Tahoe. The King fire.

And the college campus, as well as the high school, is closed today. We've had snow vacation before, but smoke vacation? That's a new one to me.

What is visibility anyway?

I heard on the radio a translation from visibility in miles to healthy vs unhealthy air quality. ( And found a chart here: pdf )

If visibility is 10 miles & up, air quality due to particulates (smoke) is Good & particulate levels are 0-40
6-9 miles Moderate air quality 41-80
3-5 miles Unhealthy for sensitive groups 81-175
1.5-2.5 miles Unhealthy 176-300
1-1.25 miles Very Unhealthy 301-500
.75 miles or less Hazardous over 500

So my question was, just what do they mean by visible? The very farthest haziest hill? One of the intermediate layers of trees? Just where do we draw that line?

I found a reference to interpreting visiblity data, which might be helpful in answering that almost philosophical question in a useful way. USDA Forest Service- Interpreting visibility data
But I haven't found a real answer yet.

This picture was taken in Nevada City on a recent particularly smoky day. We have had lots of days with particulate numbers over 100 (microgams/cubic meter) and several over 300.

And for days now, it is noticeably hazy between 100 and 200 feet - not as bad as it has been, but smoky. And with an orange moon.


Well, I just checked another search result, and found this at Montana DEQ
1) Face away from the sun.
2) Determine the limit of your visible range by looking for targets
at known distances (miles).
3) Visible range is that point at which even high contrast objects totally disappear.

The Sun has been practicing the moon illusion

This was taken June 26, about 8:00 PM daylight time. As you can see, not yet sunset. But the sky was very smoky, and it was possible to look right at the sun, which looked overall orange. And, as it neared the horizon, it looked very large, like a harvest moon.

For a couple of things about the moon illusion:

http://illusionsetc.blogspot.com/2005/11/moon-optical-illusion.html

http://www.lhup.edu/%7Edsimanek/3d/moonillu.htm

One of them mentions that the sun does it too, except that we can't look directly at the sun, usually. Well, that day it was smoky enough that we could. Here it was large and orange. Some places, the smoke caused a lavender sun, as at Arcata over on the coast. Wish I'd seen that.

http://yubanet.com/scitech/Unusually-widespread-haze-is-causing-a-rare-atmospheric-optics-phenomenon---the-lavender-sun_printer.php

A couple of days later, it was a surprise to see real light and shadows again, it'd been so long.

It's getting smoky again.

Where there's smoke . . .

There's fire? Well, somewhere, but not here. The closest is near the little town of Washington. But there're fires all over N California, more than 840 of them started by one lightning storm last weekend. The previous record was 73.

On Saturday, some friends and I had gone to Downieville for their Gold Rush Day; costumes, shootouts (picture 2 terrified little kids in a twin stroller, 10 ft away from a victim), stagecoach rides, food and crafts. And an appearance at the little local theater (in which the original Mark Twain had spoken) by "Mark Twain", the celebrated lecturer. We went especially to hear a friend who was providing the live music for Mark Twain's performance.

During Mr Twain's talk, the lights went out. When they came back on a minute later, and Mr.Twain was reclining in a chair, instead of standing behind his lectern, we thought it was part of the show. Then the lights went out again, and stayed out, while we heard repeated thunder outside. So there was Mark Twain, lecturing in the dark, in a little old theater, in a thunderstorm.

Very Old West. But unfortunately, no rain. So there are lightning fires all over, many still burning. And smoke everywhere, for days now.

Looking at the hills and trees receeding into the smoky distance, it made me wonder just how smoky the Italian Renaissance was. I think I remember that that was when painters discovered "atmospheric color", in which the more distant landscape elements are, the lighter and bluer they are. And I think the answer might be, not this smoky, but more than nowadays, judging by the backgrounds to some of the pictures.

I had opened some windows last night, to cool the house off, and because there was less smoke. Then about 3:00 AM it got more smoky again, and I went around closing windows. (Well, not the ones that require climbing a ladder to take the screens out, not in the dark without my glasses on.) And the moon was as copper-colored as it was last summer during its eclipse. And the sun rising this morning was flame-colored.

Another thunderstorm due this Saturday.

Update: the final total of fires for that storm was somewhere around 1200!