Remember that great Harold Arlyn song about smog? He was pretty upset when he wrote it I would imagine. Btw, the song was covered later in the 1950s by a group called The Platters…
Below we have a shot of some late afternoon pretty, undulating Cirrus or Cirrostratus… (NOT!)
That was a trick question, actually it wasn’t a question, but it was meant to trick you before you saw the exclamatory statement, “not!” Perhaps, I was thinking, you would seriously consider that this WAS a photo of cirrus for just that instant…but then you would be wrong!
But below, for those with the Calibrated Eye, found only in the most discerning of sky watching folk, you will IMMEDIATELY recognize that those waves, undulations in the sky above the tiny Cumulus fractus cloud at the right, is a smoke layer. Most likely 15,000 to 20,000 feet above the ground, that is, its also well below the normal Cirrus cloud level. This is, at present an “eyeball” estimate by yours truly. How can I find out the actual height? Maybe in the TUS rawinsonde balloon data. Smoke layers like this are often made visible by a moist layer because the smoke particles fatten up a bit and are made visible because they have gotten that bit larger and scatter more sunlight. So, this shot was taken near the time of the balloon ascent, and so I will now look and see if there was a bit of humidity around 20,000 feet above Sea Level (balloon data are reported in heights above sea level, not above ground level.) Farther below is the Tucson sounding from our friends at the University of Wyoming, which I had not yet looked at whilst (British spelling) writing the above.
As you can see, while there is a “pinching in” of the temperature and dewpoint traces representing the height of the Cumulus fractus moist layer, there really is nothing but a slight moistening (where the lines pinch in a bit) above that lower moist layer. So, it would appear that my hypothesis of a moisture layer enhancing the smoke layer should be rejected. But, as a scientist, I don’t care that I am wrong, because it is WRONG to care about whether you are WRONG as a scientist because we are detached from our hypotheses and only seek truth. Hon, could you get me a new pen since I just smashed this point on this one? Thanks.
BTW, if you were on a flight descending through this smoke layer, it would have appeared as though an ugly, thin black line of haze, because, after all, smoke is mostly hydrocarbons which are dark chains of molecules.
So why is it white here, when the sun is behind it? This is due to “forward scattering” of the wavelengths of sunlight, interfered with by those molecules of smoke, which are, in a sense dispersed. If you had looked to the opposite direction, to the east, you would not even have seen this layer. The tiny droplets in the Cumulus fractus cloud are really scattering the light around its edges where droplets are likely smaller than 10 microns in size, though at that size, about ten to a hundred times larger than the smoke particles.
The waves in the smoke illustrate the virtually ominipresence of waves in the atmosphere. We just don’t see them unless there is a smoke or cloud layer.
Not really, since I will, a bit later, see if I can post a trajectory that will show where this layer came from.
The last figure shows air trajectories for 72 hours at three different levels above ground level and each of the end points are at Tucson AP. Its clear from these trajectories that this “long range” transport haze layer shown in the first photo came out of the Pacific; it was not a part of any regional fires. Haze layers like this have often been observed to come all the way across the Pacific or even from Alaksa in the spring and early summer because the storms in the Pacific are weaker, and can’t wash the smog out. With the jet stream still very strong at levels of 10-30 kft across the Pacific at this time of year, these layers can then make it across pretty much intact.