That's a report written for the general reader?!? --- Frank C. Wimberly 140 Calle Ojo Feliz, Santa Fe, NM 87505
505 670-9918 Santa Fe, NM On Mon, Jun 14, 2021, 1:09 PM <[email protected]> wrote: > Dear Phellow Phriamers, > > > > After an ox-stunning spate of hot weather, we are now back in the 59 > degree fog bank here in sunny Massachusetts. I cannot go out in the > garden, so you all are the “beneficiaries” of my being at loose ends. > > > > As one might expect, when Meteorology developed between the wars, it took > on a military metaphor. There were armies of warm and cold air that fought > for control of the landscape. Between them were “fronts” where warm air > would liberate the land only to be reconquered by the cold air. The > fronts were ideally thought of as sharp changes in temperature, dewpoint > and wind direction accompanied by a fall and then a rise in pressure. I > used to draw weather maps as a kid from the station reports on SW radio, > and I found it much harder to locate fronts than the metaphor allowed. It > seemed more like a contest between guerilla units than the advance and > retreat of disciplined armies along a front. In fact, when I wrote the > weather book, I couldn’t find an archetypal weather map that demonstrated > fronts cleanly, and so had to draw the fronts and then *make up the > observations to illustrate the concept.* > > > > I read forecast discussions obsessively, partly for the science and partly > because their language is so rich and tortured. Talk about metaphors! In > any case, these discussions are becoming harder and harder to read purely > in terms of military incursions at the surface and more and more a matter > of upper=air fluid dynamics. I thought perhaps that was because I have > been living at 7000 for a year-and-a-half with more than the quarter of the > atmosphere already below me. > > > > But now I am back in MA and the forecast discussions are still talking > about upper air features as much as they are about surface ones. Below is a > current discussion, marked up by me to translate some of the Jargon. It is > full of references to upper level events. > > > > Now here is my quandary. Given Critchlow’s Law [LAYERS IN THE ATMOSPHERE > DO NOT MIX [ but they can be STiRRED —NST]], how on earth do events in > the upper atmosphere affect events in the lower atmosphere. Think of > those jet streams roaring along a 100 mph up at 30,000 feet. They contain > only 10 percent of the mass of the atmosphere. How are we to thinking of > them as affecting anything below them. What metaphor is at work when we > think of the ridges and troughs aloft as causing the highs, lows and > front’s at the surface. > > > > Also, do jet’s use more fuel or less fuel when flying with a jet stream; > on the one hand you would expect less because they are getting help from > the wind; on the other you would expect less because the plane has to fly > faster to stay aloft. Or perhaps the same because the two factors > compensate for one another? > > > > Anyway, here’s the forecast discussion, as annotated . > > > > > > Tuesday Night through Friday: > > > > Rain from the daytime Tuesday period come to an end early Tues night. The > vast majority of the mid to latter part of the workweek features really > pleasant weather, under cyclonic flow > <https://forecast.weather.gov/glossary.php?word=flow> aloft (associated with > an anomalously *[= unusually]*strong upper trough > <https://forecast.weather.gov/glossary.php?word=trough> over eastern CONUS > <https://forecast.weather.gov/glossary.php?word=CONUS>) and a surface ridge > <https://forecast.weather.gov/glossary.php?word=ridge> of high pressure. Cool > pocket *[= a layer of air over head that its unsually cool for its > altitude]*of air aloft and below-normal > <https://forecast.weather.gov/glossary.php?word=normal> 850 mb > <https://forecast.weather.gov/glossary.php?word=mb> temps with strong > insolation <https://forecast.weather.gov/glossary.php?word=insolation> *[= > sunlight]*support deep mixing *[= when air is cool aloft and heated at the > surface it tends to convect, and therefore to be stirred to the next layer of > warmer air.]*; fairly small thing but opted to lower dewpoints toward the > 10th percentile NBM values each afternoon given the envisioned strong mixing. > Expect mostly sunny skies with clear nights and fairly strong diurnal > <https://forecast.weather.gov/glossary.php?word=diurnal> ranges in temps. > > > > By Friday, mid-level trough > <https://forecast.weather.gov/glossary.php?word=trough> *[= a trough is a dip > in the upper air flow, like the dip between two waves; the tops of the waves > are called ridges]*axis shifts offshore as geopotential heights *[= a > “height” is the altitude at which a particular pressure is reached. It is the > weight of the atmosphere below that point. Think low pressure, > roughly]*transition to shortwave > <https://forecast.weather.gov/glossary.php?word=shortwave> ridging*[= i.e., a > teensy ridge]*. Warming trend to temperatures then set to commence as well > with 925 mb <https://forecast.weather.gov/glossary.php?word=mb> temps upper > teens to around 20C/850 mb > <https://forecast.weather.gov/glossary.php?word=mb> *[= i.e. in the 3-5,000 > foot range. This is very generally the top of the layer which interacts with > the surface, but of course, for mother church members, it’s two to four > thousand feet below the bottoms of their shoes. ]* temps around the mid teens > C <https://forecast.weather.gov/glossary.php?word=C>. Dewpoints *[= the > dewpoint is the temperature at which water vapor condenses. Low dewpoint air > is dry air, and, therefore, heavier than wetter air around it. Since the > body’s cooling mechanisms depend on evaporation, it is also “more comfortable > to be in warm dry air than to be in warm wet air. Think swamp > coolers.]*still look comfortable (mid to upper 50s) but will see highs in the > interior push into the low-mid 80s. > > > > > > > > Nick Thompson > > [email protected] > > https://wordpress.clarku.edu/nthompson/ > > > - .... . -..-. . -. -.. -..-. .. ... -..-. .... . .-. . > FRIAM Applied Complexity Group listserv > Zoom Fridays 9:30a-12p Mtn GMT-6 bit.ly/virtualfriam > un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com > FRIAM-COMIC http://friam-comic.blogspot.com/ > archives: http://friam.471366.n2.nabble.com/ >
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