We saw some nice clouds when we took the dogs out for an evening walk Wednesday.


There were some waves and a couple of interesting features associated with the passage of high-altitude airliners. Just to the left of center there are two dark, linear features that are probably, but not certainly, contrails. If that’s what they are, they are probably old (where old means more than a few minutes). They look dark because we’re looking at the under, shaded side. They may not be contrails at all, just linear cloud features.

Just above them, however, is what appears to be a negative contrail, a linear feature of apparently clear air within a cloudy region of the sky. This is more likely to be an artifact of the passage of an airliner. A negative contrail is also called a distrail, or dissipation trail. Here’s a little closer look.


In searching around for an explanation for distrails, I found at least two. One is that the warm exhaust of a jet engine warms the air in the cloud, causing existing cloud droplets or ice crystals to evaporate. A second is that the small particulates in a jet exhaust become condensation nuclei which cause large enough droplets or ice crystals to form that they precipitate out of the cloud, leaving behind a clear region. The website with this particular explanation alternatively attributes the effect to the turbulence created by the aircraft’s passage causing greater condensation and precipitation. Other explanations don’t mention turbulence; I think it’s possible that under the right conditions, turbulence might cause a wake of sorts to appear in a cloud that looks like a negative contrail. I think that’s a different phenomenon from the particulate-condensation nuclei-precipitation explanation.

I think the second explanation (particulates-condensation nuclei-precipitation) is probably closer to right, and the warm air-evaporation explanation is wrong. My reasoning is that the same conditions that cause a condensation trail to form are being blamed for an evaporation trail. The warm (or hot, if you will) exhaust of a jet engine very quickly cools as the gases expand, which causes the water vapor it contains to condense, thus forming a contrail. I can’t think of a way that adding water vapor to air will cause evaporation.

The accuracy of the second explanation is bolstered by accounts of seeing virga or falling ice crystals from the region of the distrail.

third explanation includes some atmospheric optics along with the particulates-condensation nuclei-precipitation process that may or may not be necessary to the explanation of distrails. It relies on optical properties of ice versus water as well as on precipitation. If anyone is interested they can check out the site, which some readers are already familiar with.

On other days in other skies, I have seen what looks like a negative contrail, but these are usually a visual effect. What looks like a negative contrail in those cases is actually the shadow of a higher contrail falling onto a lower cloud deck. It’s sometimes hard to tell the difference because the lower cloud deck can hide the higher contrail, so all you see is a dark trail through the clouds that looks a lot like a view through the cloud to clearer sky.

In this case, I think what Leah and I saw was actually a distrail.

Drywall delivery

The drywall installer called on Monday and asked if he could have drywall delivered Tuesday. Of course I said of course, even though the house was too messy for them to deliver. They distribute drywall throughout the house so the installer doesn’t have to move it so far, so the floors need to be clear of construction material and debris. That meant I spent the rest of the day Monday and the morning on Tuesday clearing lumber from the garage and various insulation-related stuff from the house.

Here’s the first load going into the garage.

unloading in the garagr

The truck has a long boom that picks up a stack of drywall and swings it around right to the door.

Neither the delivery guys nor the installers like to lug drywall up stairs, so they try to unload directly into each level of a house. Our floor is three steps up from the garage, so they used a bedroom window.

swinging drywall

Our windows are double-hung, and made so that each sash comes completely out.

We (or the drywall people) are lucky I wanted deep windows in our bedroom. If you look at the closer window below, you can probably tell that it isn’t tall enough to unload drywall through. Our bedroom window is just tall enough.

into the window

The drywall just fits. Here is one of the delivery guys taking a few sheets into the bedroom.

unloading in the bedroom

At the extreme right of the photo you can see a little of the flexible silver duct the heating and AC contractor installed Monday. It will be used to blow warm air from the wood-burning stove in the living room to our bedroom.

I spent the rest of the day Tuesday building a small chase to hide that duct. In addition to that, I need to insulate a few more stud bays and put up my attic insulation measuring sticks. I cut about 80 20-inch long pieces of 2×4 to nail to the ceiling joists as depth indicators. I ripped them on my table saw at home right after lunch. During that process I did not cut off any body parts, but I did stick my left index finger into the spinning blade. It bled (not as much as I expected, being on a daily aspirin). I hurried inside, a little afraid to wash it and see how much damage I did. It chewed out a small bit of flesh and a little of the tip of the nail. It doesn’t hurt to speak of, which suggests to me that it got just enough of the tip of the finger to destroy the nerve endings. I think I’ll end up with a little scar there. And, of course, I’m finding out just how many times you use the letters f, g, t, r, c, and v when you type.

The delivery guys distributed the drywall to various places in the house, ready for the installer to start work. I expected to be ready for him by the weekend, but now I think it will probably be Thursday before I call him.

Doberman Cyclops

Over the years I have brought home various stuffed animals for Leah, which we keep on a cedar chest in our bedroom.

Sam likes to chew on things.

I think you can see where this is going.


We have left Sam in the house many times since he came to live with us, and he has caused only minimal damage. He has chewed up several socks and a couple of Leah’s bedroom slippers, usually early in the morning when he gets up before us. He tore up a stuffed hedgehog dog toy, and he chewed on a little stuffed gorilla. No big deal. Then on Wednesday when we went for our weekly huevos ranchers lunch, he chewed up the face of the Valentine’s Day doberman I gave Leah, as well as Minnie Mouse’s foot and ear.

There’s not much we can do about it other than try to remember to keep chew-attractive items out of his reach.

Sly in the Mule

sly in the mule

This is Sylvester’s favorite place to crash when he’s outside. Leah put some towels down as a pad, but it still can’t be as soft as the pet beds that are on the garage floor just out of the picture. But cats make their own rules about this kind of thing.

Sylvester has been having urinary tract problems, so he has decided to make his problem our problem, too. He has taken to spraying in various places around the house, including in the garage. “In the garage” includes the windshield and back window of our car. It’s not an endearing trait. Leah says she really likes Sylvester, aside from that little problem, and the fact that he and Smokey make Dusty’s life a living hell.

But I have to admit that he’s a cool character.

Inspection passed!

The building inspector came back for a re-inspection on Tuesday. We passed.

He basically took my word for everything that wasn’t easily visible, like the framing repairs. He had noted several plumbing issues, which I told him had been corrected. He suggested that we add some metal tie straps to the side framing of the garage doors, to help prevent the garage from blowing away in a strong wind (assuming we had left the garage doors open, which we won’t). We needed four angle brackets specially designed for that purpose at a cost of $20 each. That’s a lot for metal brackets, but not so much in the context of a cost of the whole house.

I bought the brackets and spent an hour and a half drilling holes in the concrete pad of the garage, installing concrete anchors and bolts, and hammering 25 nails into each bracket.

The inspector said we can start drywalling. The drywall contractor said he can start pretty much when I call. Several things have to be done first. I have to complete the insulation, which I think I can do in a couple of days, or one if I’m really diligent. On second thought, make that two days. The heating and air-conditioning contractor is going to install a duct we’ll use to blow warm air from the wood-burning stove back into our bedroom. That should happen this week. The chimney man will install all the wood stove fittings from the ceiling through the cap on the chimney. That should happen early next week. I want to install a walkway in the attic that will give us access to the whole-house fan and the warm-air blower when the attic insulation is done. That should happen by the end of the weekend.

And then drywall. And then paint. And then electricity. And then the heating/air conditioning contractor can complete the HVAC system. That will allow us to condition the air in the house, which will allow our wood flooring to get used to the conditions that it will experience when we move in. And then wood floors in the living room, hall, and bedrooms, and maybe kitchen. And tile in the bathrooms, and maybe the kitchen. There are several things that may have lead times of several weeks, so we need to pick them out now and possibly order them within a week or so. That includes wood flooring, bathroom vanities, and possibly some light fixtures.

And, of course, I have to finish up the basement in our current house, hopefully before the end of May.

We need to get busy.