The last few days I’ve been up and awake at about 6 am. (Shocking, I know ;-) We have a car in the shop, so I’ve been driving the spouse to work. Since the 300 TD Diesel Wagon died, her ‘backup car’ doesn’t exist. While she can drive a stick shift, it is more of an ‘emergency only’ skill.
The 300 TD, for any who missed the footnote, has a ‘spun #2 rod bearing’. I inspected the crank and bearing inserts yesterday. Rough gall and smear where their ought to be polished metal. I suspect that “spun” is not an accurate term. The little notch / tabs on the ends that key the bearing material into place are intact, so the material didn’t ‘spin’. It looks to me more like some oil interruption or bit of ‘junk’ in the oil caused a lube failure and overheat / melt of the material, then an abraded and seized bearing. The engine is now in pieces as the mechanic decides what to do; boat or house payment for the year …. sarc;> ?
In any case, I’m driver while her primary car gets the suspension fixed and tires done.
Which means I’ve been up at the crack of dawn, and looking at frost on the windshield of my car (that is parked outside).
Frost. Condensed frozen water.
Water that came out of the air.
Water that, as a GHG, ought to cause a spike in cooling when it has left the air, and a spike in warming when it has evaporated back into the air the next morning. IFF the GHG thesis is correct, there ought to be some kind of evidence as we have grams / sq.meter of water coming out of the air, then going back into the air. Fairly well defined in time as well. For the morning frost, it looks like it starts melting when the sun hits it and is largely done by 10 am. So a 2 hour band from 8 am to 10 am mostly. (It varies a little bit as some places are more shaded than others).
We’ve had nearly no air flow / wind. Nice for having a stable comparison window. Also clear sky, no clouds, and no precipitation. Just air, sun, water vapor / frost cycling. Pretty clean ‘test case’.
The only “odd bit” is that the San Jose temperature is measured at the airport some distance away. I don’t know if they get frost on the grounds there. Still, the local urban bubble is pretty much one air space. SJC air slides over my head not too long after it leaves the airport on most days. (We are downwind for the normal wind patterns).
So lets look at ‘the week so far’ graphs from Wunderground:
Looking at this, even knowing that the last three mornings have had frost ( Wed, Thur, Fri); I’m not seeing much / anything in the way of a change of slope at frost evaporation / condensation times. Looks substantially directly tied to sun angle during the day and decaying heat loss at night.
Lets look at a close up of just one day, yesterday:
I was scraping frost off the windshield at 7 am. Roofs were covered with it, so were lawns. All the way over a 20 mile drive, lots of frost. This wasn’t just a local one block or two kind of thing. The regional air was significantly reduced in the largest GHG of water vapor during the late night, then it rushed back in between about 8 am and 10 am. Is there any clear indication of MORE and more rapid heat loss / cooling at the ‘after 2 am’ times? How about a break in the smooth heating increase with sun angle as the GHG floods the local air around 9 am? Not seeing it? Me neither.
In fact, the rate of cooling slows as the frost covers the surfaces later in the night. The rate of warming slows as the GHG is at it’s peak and we move past noon. There is a great deal of evidence for a “directly proportional to sunshine” temperature curve, and negative evidence for the large flux of the largest GHG.
It would likely be better to repeat this test with other areas. Find a place where the frost can be observed AT the temperature measuring site. But frankly, having looked at some stations almost in my back yard (not posting that graph as it gives more location information that I want published ;-) they are not significantly different from this graph. No ‘step functions’ with frost formation or evaporation. Solar profile not water vapor.
So IMHO, the frost is saying that there is no visible effect from having grams / sq.meter changes in the major GHG. As the air freezes and the water vapor level drops, it just doesn’t do much. What does the dew do? Not much to heat loss to space. Nor heat gain in the mornings. The sun cranks the temperature profile in a cycle. Everything else is just along for the ride. When the sun is gone, we cool, but with ever more slow heat loss even as the GHG of water vapor is dropping and forming a layer of frost. You could make the case that there is enough water vapor that stays in the sky, high overhead, so that we’re pretty stable at the surface to heat loss. But that same case would hold for adding / removing the same grams of CO2 as are cycling in the frost.
Basically, we’re pretty well saturated in that whole IR heat loss band effect and adding / removing marginal amounts just doesn’t do much. The temperature profile is dominated by solar heating of surfaces directly during the warming cycle, then direct cooling of those surfaces down to a nearly stable temperature between about 3 am and 7 am when the water vapor GHG is at its lowest. When heat flow out of the surface is balanced against heat loss to space, at no net temperature change. Solar heat storage and extraction from surface materials dominates. Not the gas / IR dynamic. (At least at times like these where the ‘wind’ is essentially nil and convection is very-low other than mid afternoon when it is simply low.)
So that’s what frost is telling me. It’s telling me ‘never mind’ about radiative changes from GHG flux. “He’s saturated, Jim”.
In looking at several cities in the ‘select location’ tab, I keep seeing the same thing. Dew point just below min-temp. Even as far south as Salinas (about an hour or less south on 101 a farm town not near anything large). There are two possible interpretations (that I can think of). 1) That’s the way the physics works and frost forms of exposed surfaces before the temp gets that low in ‘free air’ and the heat of fusion is keeping them a degree apart in the race condition between lowering moisture in the air and temperature. 2) The automated measuring things have a high value for the low temp and frost is demonstrating the ‘problem’. One would need to ‘decorate’ a station with surface thermometers to figure out which.
But here is the graph for Salinas (that looks a lot like Lincoln – near airport – and Santa Clara and a couple of other neighborhoods around).