SCIENCE BEHIND AN AIR TRAGEDY IN SAO PAULO, BRAZIL AUGUST 9, 2024

 An air tragedy in Brazil, wing icing in the tropics, supercooled droplets, Bernoulli effect, airfoils and Newton’s Third Law. 

August 10, 2024 Sao Paulo, Brazil

On Friday afternoon, August 9, 2024 a VoePass  ATR 72-500 aircraft, with 62 passengers and crew on board crashed just 45 miles short of its destination in the City of Vinhedo, while on its way to Sao Paulo City’s  International Airport at Guarulhos, Brazil. Sadly there were no survivors.  The ATR 72-500 turbo prop plane was manufactured in Europe by a ATR, a French-Italian consortium of the Airbus and Leonardo firms. Since the early 1990s this plane has had 15 air crash incidents with almost 500 fatalities. A similar plane, an ATR 72-200 crashed in 1994, in Roselawn, Indiana in which the probable cause was icing of wings. The crash caused 68 fatalities. A US Federal Aviation Agency investigation concluded with a warning to pilots not to use autopilot in icing conditions when flying these planes. 

This VoePass ATR 72 was on a domestic flight from Parana State to Sao Paulo City with 62 passengers and crew on board, when at 11.21 PM the flight, cruising at 19,000 feet, began losing altitude over Vinhedo City about 45miles NNW of Sao Paulo City. The plane dropped 250 feet in 10 seconds, then climbed back up 400 feet in 8 seconds. Seconds later it lost 2000 feet and then it began a rapid spiraling downward fall, dropping 17,000 feet in one minute. It crashed and burned among houses in the City of Vinhedo. No local residents were hurt as the plane plummeted to the ground in a clear area among homes and burst into flames. 

Video photographs published by onlookers on the ground show the intact ATR turboprop, falling, with no horizontal speed, plunging almost straight down. The video is frightening to watch since it is clear that the plane had lost all ability to fly and was in an uncontrolled deadly death spiral to the ground.  The plane provided no visible reason to fall, it appeared unaltered, there were no flames or smoke, the wings, tail and body were intact.  The ATR 72 was simply plunging straight down like a huge piece of silvery metal.

What could have caused such a crash?  

It is winter in Brazil which is in the southern hemisphere. Though Sao Paulo and Vinhedo are located in a tropical-temperate zone, at about 23 deg south latitude, close to the Tropic of Capricorn, winter is relatively mild there. (Sao Paulo is far south of the equator as semi tropical Tampico, Mexico is north of the equator.) Average southern hemisphere “winter” temperatures for August in Sao Paulo range from 60-70 degrees F during mid day.  

Since for the most part, air is heated from the bottom up, not by the sun’s rays passing through air, but indirectly by the sun heating the earth, and then the warmed earth transferring that heat to the air. For this “bottom up heating” reason the air cools at a regular rate at higher elevations. The Normal Lapse Rate is average rate at which the air temperatures drop when measured from the ground upward. That rate is about 3.5 F per 1000 feet. 

Yesterday, (Friday, August 9, 2024) mid-day temperatures on the ground at Vinhedo were about 70F.   But the air temperature at 19,000 feet was much cooler. Using the Normal Lapse Rate to calculate the approximate temperature at the ATR 72”s cruising height indicates that the air temperature aloft where the VoePass airliner was flying was probably around 4.5F.*  

Thus where the ATR 72 was cruising the air temperature at 4.5 F was well below freezing (at 32F).  Clouds at this level often contain moisture in the form of ice crystals, and water droplets which have been cooled below freezing but remain in the liquid state, these tiny liquid drops are called “supercooled water droplets”. These tiny drops of water  less than 0.05mm in diameter, are so small that even at temperatures well below freezing (32F) they simply can not organize their relatively small number of water molecules within the drop into the typical ice crystal lattice.  So they remain in the liquid state.  However, if they come in contact with a solid surface, an ice crystal, dust, or pollen particles which may act as nuclei of crystallization, they freeze instantly. 

When the leading edge of an airplane wing flies through such a cloud with supercooled water droplets,  the drops freeze instantly to the plane wing, tail, sensors like pitots, antennae and other parts.  This ice—called “rime ice”—is heavy and adds weight to the plane but it is most dangerous on the wings where it can interfere with lift.

As you would expect, the wing is what permits the plane to rise up off the ground and also provides the  “lift”which keeps the plane aloft.  The process is complex and probably not fully understood, but in simple terms we can think of the wing as an “air foil” with a cross sectional shape characterized by a flat undersurface and a slightly rounded or cambered upper surface. The wing functions as an airfoil (to create lift) only when it is moving forward through the air. In simple terms, the air flows smoothly over the top and bottom of the wing in cross section. The flow of air over the top surface is forced to speed up as it traverses the curved surface (a longer distance). It is this more rapid flow which creates lift. The Bernoulli Principle states that the pressure of a fluid in motion is inversely proportional the speed of the flow. Thus the pressure above the wing (air foil) is lower on the upper, curved, cambered surface than that of the bottom flat surface where pressure remains unaltered.  Imagine  “stretched out” or lower density molecules generating a zone of lower pressure along the upper wing surface.  This does not occur on the undersurface where pressure remains at its original higher level of pressure. 

As a result, the moving  aeroplane wing generates a region of lower pressure all along its upper surface.The longer the wing the more lift it can develop.  In a definitely non-scientific sense, the wing can be imagined as being “sucked” upward* by the air flowing smoothly over the upper cambered surface.  As long as the air can flow smoothly in streamline flow over that surface the wing provides lift (or is “sucked” upward ) and this disparity in pressure helps to keep the plane aloft.  (It is noteworthy that the angle of attack of the wing also creates lift. The angled upward wing tends to direct air downward creating a force (Newton’s Third (equal and opposite) Law) that pushes wings upward).  

Thus it is clear that any disturbance to this smooth air flow or “streamline flow” over the upper cambered wing surface,  such as turbulence caused by rime ice, can reduce the speed of the flow and destroy the Bernoulli (“suction”) effect of the upper curved surface.  This is the likely problem which caused this tragedy. 

How does ice form on wings?

As noted above high clouds at temperatures far below freezing have moisture in both solid and liquid form. When planes encounter supercooled droplets aloft ice can form along the forward or leading edge of the wing. Rime ice has a rough surface.  It causes the air to flow irregularly in what is called “turbulent flow”.  This form of air flow destroys the lift effect.  Rime ice thus destroys the rapid smooth flow over the upper wing surface. The slowed flow of air along the wing edge causes loss of lift, or when excessive may cancels out lift altogether.  On both wings,  icing may cause the plane to lose elevation instantly. When only one wing is impacted, that wing loses lift and the plane may bank sharply in that wing’s direction, causing the aircraft to begin an uncontrolled downward spiral. 

In the early years of flight, most planes flew well below levels of high clouds where supercooled droplets would likely be encountered.   When aircraft began flying at high altitudes, methods to control icing on wings became essential for safe flight.There are several methods used on the most modern airliners. One more modern solution is to direct heated air or other fluids derived from the jet engines or the prop engines to the wings when required .These “hot wing” planes melt rime ice which may accumulate on the wings and leading tail edge. Another method common on many older types of aircraft is a rubber boot which encases the forward edge of the wing. This flexible boot can be pumped up with air when necessary which causes the boot to expand and crack the adhering ice which then is driven off the wing by air flow. 

The ATR 72 model has this latter design. One problem with this system is that in cases when icing conditions are extreme or when such conditions are repeatedly encountered, multiple use of the system may form ice encrustations which break off and slide rearward only to refreeze onto the central cambered portion of the wing, beyond the rubber boot. When that occurs the aircraft  loses lift rapidly and plunge to lower levels. 

Though "icing" seems the likely cause of the tragedy in Brazil, what seems compelling when looking at the facts and circumstances from afar is often only the first hypothesis in perhaps a much more complex circumstance. We must await the full technical report on this sad air tragedy.

  One can only feel pain and sympathy for the families of the more than 60 passengers and crew who lost their lives in this terrible crash. One hopes those who investigate these tragedies can find the cause and make recommendations regarding flight safety that will make such tragedies very much less common.*  

(Though in relatively uncommon meteorological circumstances such as “ice storms” supercooled clouds may produce rain drops cooled to the freezing point. These liquid drops at freezing temperatures (not supercooled) fall into lower warmer levels of the atmosphere close to ground level.  There they strike power lines or tree limbs and branches and as they strike these surfaces minor evaporation further drops the temperature causing the drops to freeze on contact, and over time building up thick layers of ice with often devastating consequences to trees and power-lines.) 

* More recent (September 2024) reports indicate that indeed the Sao Palo crash was caused by wing icing. To this author, it seems reasonable to request that the ATR 72-500 turbo prop plane manufactured in Europe by ATR, a French-Italian consortium of the Airbus and Leonardo firms which in most circumstances appears to be a safe practical airship,  should be grounded and refitted with more modern deicing equipment than its original design system before it can be safely flown again.  Icing is not a mid latitude or cold climate issue. Rime icing can occur even close to the equator….. in Brazil.

  

*There is of course no such thing as “suction” but it may work as an idea aid.

*Normal lapse rate is about 3.5F per 1000 feet.

• (19 X 3.5F)- 70 F = Temp at 19,000 feet)) or 19 X 3.5 =66.5F, 70F-66.5 = 4.5F. 
• Brazilian meteorological company reported severe icing in Sao Paulo State at the time of the crash. 

ATTACK BY ANGRY HEN TURKEY

On the North American Wild Turkey (Meliagris gallopavo) 

The wild turkey is a dry ground chicken-like bird native to North America. The species originally occupied all of North America east of the Rockies and south of Canada, as well as isolated areas of central Mexico and central California.   

Adult male turkeys or “Toms”, (also called  “gobblers”) may weigh up to 25 pounds, with a body length of about 50 inches and may stand at two feet high. The hen turkey is smaller and more slender and may weigh about half that of a gobbler and is correspondingly shorter. The wing span of a mature male bird may reach well over 4 feet.  Turkeys are dark-gray-brown or coppery colored. Toms have a reddish head and often long, red fleshy wattles on their throat. The male also long tails which they can spread out into impressive fan-shapes in breeding displays as well as a fleshy“beard” which hangs from their breast. 

Turkeys can fly quite well and do so regularly to avoid predators or to reach roosting perches above the forest floor. They can fly for distances of a quarter mile (@400 meters) or more, often remaining close to the ground.  They often roost in trees at night and can fly up to tens of meters to reach these roost sites.    

Not so long ago I was attacked by an angry hen turkey attempting to protect a brood of eight young in her care.

The incident occurred this way:

While driving on a narrow country road winding through a local wooded area, I was altered by the flash of red break lights ahead that the auto ahead of made an abrupt stop. 

Beyond the stopped vehicle, I could see the cause, it was a hen turkey slowly and deliberately crossing the road. And behind her fowlling in a neat orderly line were seven tiny poults or “baby” turkeys.  I watched, as in a military-like precision the line of tiny gray poults disappeared one by one into the brush on the opposite side of the road. 

The car ahead started to move. Alarmingly, just at that moment, an eighth poult emerged from the far side of the road, running frantically to catch up with its mother and siblings. Again, the car ahead stopped short, and the last poult skittered past the front tire to disappear into the bordering brush. Only then traffic slowly moved on. 

What a lovely sight. Turkeys have become so common these days, that regular polite interactions with this adaptable, large wild bird leave most suburbanites nonplussed. Secretly we  marvel at the  ability of this large wild bird to survive and prosper in a dangerous man-made world of scattered remnant woodlands, speeding traffic, housing developments and numerous domestic predators (i.e. cats and dogs). 

The turkey’s success in suburbia is, in part, the result of the return of forests! New York State’s land area is almost two-thirds forested.  The 18 million acres of NY State forests represent about 61% of our total land area.  Much of this forest land is excellent turkey habitat.  Then too, the Wild Turkey is a large bird—most weigh about 15-20 pounds. At that size, they are able to effectively defend themselves from the most common small predators found in modern forests. Then too, they are also excellent short distance fliers.  They can escape certain predators by flying.  Flight also permits them to exploit scattered and isolated feeding and roosting sites which occur within the highly divided and segmented terrane of suburbia. Remnant patches of wood lot and feeding areas isolated by large scale housing development are often unavailable to other terrestrial-bound wild life, by heavily trafficked busy road ways.  Turkey flocks can access these areas.  

Their habit of roosting in trees at night, which provides them protection from terrestrial predators. Their tendency to flock together offers further protection,  They are also pretty smart. 

To survive in a suburban habitat the turkey must be highly protective of its young. On an occasion in early spring described above, I encountered a mother hen herding eight tiny gray and fluffy poults.  The area she had chosen for her brood was a brushy woodland crossed by an asphalt-surfaced bike path.  I habitually walked on this path and had seen this same hen and her poults the day before. (Perhaps the one seen and recorded above crossing the roadway.) 

On that day I walked briskly along and coming up over a rise, I observed the heb turjey ahead . As I approached, she was herding her brood of poults across the path.  As I approached I counted three poults follow her across the path..but the other five I had seen earlier in the day were slower and I assumed they were behind her.  As I came up closer, I realized  that the hen and some of her poults were on one side of the path, while the other five (?) were on likely on the opposite side. Her brood was apparently separated by the path upon which I was walking.  

As a result, as I approached, I was met with angry cackling and clucking from the high grass bordering the pathway. The cackling became louder and soon the bobbing gray head of the angry hen appeared just above the two-foot-high grass. She rushed along close to the side of the path, partly hidden by the high grass, anxiously pacing along with me and continuing her frantic clucking. 

I found myself between her and the other members of her brood. Not frightened of her, and sure that I could outpace her, I continued on my course moving along a bit more rapipidly. But angry turkeys can run very fast on the ground. As I sped up into a trot, she sped up easily moving out ahead of me.  Then, without warning,  she stopped and turned toward me to jump into the air, flying directly at me. She rose up steeply off the ground, her feet outstretched,  aiming directly for my head!  I ducked, as her wide wings brushed over my head, and I could feel a puff of air as her wings passed over my head.  Her  long reddish claws passing  just over my hat.  I shifted my position, yelling and swinging  my arms out wide.   But this made no impression, for she landed on the opposite side of the path, and simply turned and made another flying pass at my head.  

I stopped to make another  attempt at a defense by jumping up and down waving my arms vigorously and yelling: “Scat..Go Away, Scat”, but this seemed only to arouse her further.  At this point, a mental image of the  velociraptor  attack scene from the film “Jurassic Park” flashed through my head.  Her movements and angry look looked very reptilian like as she landed this time on the center of the path, to face me directly.  She had my number now.  She must have realized, I was more frightened of her than she was of me. 

The angry hen turkey clucking loudly, faced me from the center of the path. She stared at me with one angry eye, clucking loudly which made her long neck throb and the dangling gray wattle on her head jiggle violently, She spread her wings wide.  The wide wings seemed to more or less cover any route of escape I had. So, I simply turned around and retreated. But that was a mistake. 

Seeing my back in retreat, seemed to only encourage further attack. She flew at me again. This time knocking the hat off my head with her feet.  I grabbed my hat and turned to face her, waving my soft hat as ineffective protection from her sharp claws, as I slowly backed away. I did notice that my voice cracked as I yelled and my lips felt dry.  Facing her I continued slowly to retreat for about fifty feet which seemed to get me out of her threat zone.  At that point she quietly turned into the brush and disappeared. I didn't wait to see if she rejoined her poults.  I turned and walked briskly back to where I started, with a pulse rate much higher than usual for a brisk walk.

When observed in the field these wild birds are a startling reminder of the underlying principle of the fact that the natural law still governs us all. Though commonly seen, on roadways, bike paths and elsewhere the life and history of this now much more common species is very little known. Even their very name “turkey”  elicits questions.

Addendum.

On July 30,  2024, I observed what I assume to be the same hen turkey in the same area described above. By this date observed only four (4) poults with her. Fortunately they were all on the same side of the path, and as I walked by, she clucked” them along into the deeper brush on that side of the path. 

On September 13, 2024 I again encountered the same hen turkey with her brood of poults. Again there were four. At this time they were about as big as a yearling hen chicken…They were feeding on seed heads of grasses along the Rail Path. The hen also appeared to be feeding on the red berries of the Russian Olive (Eleagnus augustifolia) which is a common species along the Rail Path in this area. 

WHITE-TAILED DEER, BROWSING PREFERENCES

 MIDSUMMER BROWSING PREFERENCES OF A SUBURBAN LI, NEW YORK, WHITE-TAILED DEER HERD 

The White tailed Deer (Odocoileus virginianus) is a medium sized antlered ungulate native to most of North America and Canada, Central America, and the northern third of South America with isolated populations in parts of Central America.  There are an estimated 30 million deer in North America (See wikipedia) which in suitable habitats may weigh from 170 lbs for a buck (male) to 120 lbs for a doe.  In farming country or forested areas White Tailed Deer have a natural home range of about one square mile.  The species feeds mostly as a browser, feeding on the leaves and tender twigs of trees and brush, using their lower incisor teeth to tear off plant food. TheY have no upper incisors. They also eat grass and other low growing non-woody species as well as domestic crops such as corn and vegetable crops. Fruit and nuts are eagerly consumed when available as well.  They drink water when it is available, but can get most of their water from the food plants they consume as well as water produced by the digestion process.  Deer are ruminants that eat plant foods which, after maceration by molars, enters their stomach where fermentation  takes place in part of their four part stomach. They then regurgitate that food to chew it again for further digestion aided by microbial action. 

The most abundant and nutritious food sources for deer are found—not in the interior of shady forests as some might suspect—but on the margins between forest and open farm field, meadow, or roadsides. These often sunny, boundary zones or “edge habitat” produce the most and the greatest variety of plant food for deer. 

Suburban areas provide adequate habitat for deer since these partly urbanized areas are characterized by the natural spaces being  divided up by roads and housing and commercial areas which thus provide abundant and desirable “edge” habitat for deer. The suburban deer has few or no natural predators, and most often, no human hunters. This habitat also has well nourished, well watered plant foods in the form of grass lawns, foundation and decorative plantings, home gardens and well tended fruit and shade trees.

The deer population in Suffolk County, New York is estimated to be between 25,000 to 36,000 head as of 2014 (NYSC DEC Aug 4, 2014). With larger deer herds in suburban areas deer food preferences must have an impact on what plants may survive and prosper in parks, natural preserves, waste places.  plants wild are more likely to be impacted by deer browsing. Heavy browsing can alter population dynamics and intensify exacerbate invasive plant dominance or spread. 

But what do deer prefer in mid summer when heat may affect need for water, and when deer browse seems to be plentiful, at least to human observers?  What plant species are deer browsing on and what do they seem to prefer at the height of seasonal plant growth.  It is obvious that deer do seem to have specific preferences, which tends to limit their browsing locations and movements. The following brief observations may be of interest. 

Deer browsing preferences were observed in mid-summer 2024 along a rail road right-of way on Long Island Brookhaven Township, Suffolk County NY. This visual survey was conducted on July 18, 2024 along both sides of a one mile route of a bike-walk-jogging path, a former east-west Long Island rail road right of way, locally known as the Rail Path in Brookhaven Township between Rt 25A and Miller Place Road. The four meter wide asphalt path is bordered by a swath of recently cut mixed grasses and forbs which is in some areas confluent with patches of woodland of varying acreages. These provide adequate refuge or cover for deer. While the path itself is a continuous zone of edge habitat where they feed.  Parts of this zone are occupied by electric utility poles and pylons. Parts are bordered by housing development and others as noted above by forested areas. Whitetail deer are plentiful along this stretch of the “Rail Path”. 

Observations and records were made of the species of brush, vines and trees which showed obvious signs of recent deer browsing, branches and twigs devoid of leaves, with only petiole remaining, tooth marks, chewed twigs, branches bearing remnant leaves and chewed off tender terminals.

SPECIES OBSERVED BROWSED ALONG RAIL PATH..BETWEEN NY RT 25A AND MILLER PLACE ROAD, JULY 18, 2024.

Fox Grape(Vitis labrusca) especially young leaves and tendrils. (Most commonly browsed)

Multiflora Rose (Rosa multiflora) young leaves and tender branches.(Frequent)

Japanese Bittersweet (Celastrus orbiculatus)..tender leaves and tips of vines. (Frequent) 

Staghorn Sumac (Rhus typhina) both young leaves and especially the red fruit bodies (drupes0 of the terminal panicle were eaten off while the greEN panicle (infructescence) itself was left relatively undisturbed 

Field Bindweed ( Convolvulus arvensis) vine tendrils, flowers and leaves. (Frequent)

Catalpa  (Catalpa bignonioides) Leaves tender twigs browsed.(Few)

Flowering Pear (Pyrus sp) terminal leaves and twigs browsed.(Few) 

INCIDENTAL OBSERVATIONS (not recorded at this date). 

Other species browsed: 

Poison Ivy (Toxicodendron radicans) A telephone pole with heavy growth of the poison ivy climbing vine was observed to have been browsed by deer. Typical height, and vegetation effects of deer browsing were observed. This during early spring of 2024.

Chicken Mushroom (Laetiporus sulphureus) observed a large shelf fungi on a lightning struck Black Oak tree about three feet above ground. The fungi had clearly been chewed by ungulate. On a later observation two days later most of the remaining portion had been chewed off and removed. This observation in the early spring of 2024 within the one mile path zone of this report 

Virginia Creeper (Parthenocisssus quinquefolia) Ocasionally browsed in this study area. But most observations of browsing were associated with presence of C.orbiculatus. Perhaps this species simply eaten by deer accidentally as they seek favored Bittersweet. 

 

VERY COMMON SPECIES NOT BROWSED AT TIME OF THIS OBSERVATION

Though very common among other forbs, brush and minor tree species and available at heights deer could reach all along one mile path, no evidence of browsing was observed on these common species.

Eastern Red Cedar (Juniperus virginiana) This species is heavily browsed in winter but no observations of browsing were observed at the time if these observations. Most trees had abundant light green new terminal branch growth but none showed evidence of browsing.

Russian Olive (Elaeagnus angustifolia)

Black Locust (Robinia pseudoacacia)

Black Cherry(Prunus serotina)

Norway maple (Acer platanoides) 

Paulownia tree (Paulownia tometosa)

Poke weed (Phytolacca americana)

Red Raspberry (Rubus idaeus)

Crown Vetch (Secuigera varia)

CONCLUSION: Wherever Japanese Bittersweet (C.orbiculatus) or Fox Grape (V. lambrusca) were available to be browsed  by deer, i.e.  within 1.5-2 meters above ground,  in the described study area these species were heavily browsed.  One may use such browsing as high probability of White tailed deer in significant populations levels. 

Addendum

By July 30, 2024, much of the preferred browse noted above along the Rail Path corridor had been consumed by deer. Late in the month this author observed the preferred species noted above had been heavily browsed and were in the process of regrowing leaves on branches that had been denuded or browsed clean. These new growths appeared unaltered by browsing deer. 

On these last days of July perhaps being hungry, deer were observed browsing actively on foundation plantings located on adjacent  property. The browsed foundation plant were identified as  commonly planted, Yew (Taxus sp?) Probably  T. Canadensis)  On July 28, author  observed young fork horn buck and yearling  doe grazing in high grass which borders the Rail Path.  Apparently the preferred species described above were not enough to satisfy their hunger and late in July deer here began grazing. 

By mid to late September, acorns were falling from oaks, and these were eagerly eaten by deer. A pair of yearlings were observed regularly gleaning acorns fallen to the roadbed. These two favored a busy corner along North Country. Road where fallen acorns were often crushed by vehicles truning into a side road. The crushed acorns seem to be preferred…or perhaps  they were simply more easily seen and exploited on the hard asphalt surface.  Sadly the attraction to these  crushed acorns brought them into  contact with a busy road. 

In addition, around this time fallen fruit, apples, and pears fallen onto lawns and even close to homes were also eagerly eaten.  

HEAT WAVE, HUMIDITY AND WHY DO I FEEL SO UNCOMFORTABLE TODAY?

 

We have had a streak of very uncomfortable weather lately. My thermometer outside is recording 90F (26C). The psychrometer records relative humidity at 99%.  On the “how it feels’ chart —I feel terrible. My skin is damp and clammy. I’m tired. The only relief is a dip in the back-garden pool, or a trip down to the beach. One senses relief and revival immediately after plunging into the cooling liquid. When that is not possible,  one must retreat into a refrigerated room, or a climatically controlled building, or a big box store where simply  entering offers immediate relief. 

My daughter, who happens to be in Rome, Italy on a school education tour called in the early morning to report that the temperature there at mid day was 93F or 34C).  Her text stated, “Don’t worry Daddy, It’s not too bad here. We had lunch at an outdoor cafe, where we sat under a shady arcade. A faint breeze made it very pleasant.”

How could that be?  After closing the text app, I looked up the weather in Rome for that day. The Italian meteorological society reported that the temperature maxed out at 35 C (95 F). and  relative humidity was  32%! That is the difference.

Humidity in the air. That is the culprit.

Why does atmospheric humidity make such a difference? 

It was about two million years ago in East Africa where the human species (Homo sapiens) arose, at a time when the East African climate was moderately warm and very dry. Humans are adapted to a near desert climate, to a dry air and higher temperatures. 

One of the more significant evolutionary advantages of humans is their means of maintaining a constant body temperature.  Some organisms (most) only respond to ambient (outside) temperatures, being more active when the air is warmer and less active when cooler or cold air replaces the warm. These animals (poikilotherms) respond with reduced activity and lower rates of  metabolism in cold air . For some (i.e. reptiles) such variations in body temperature and changes in metabolism actually helped to improve their survivability. When low temperatures coincide with food scarcity, a common occurrence in nature, reptiles simply go into a low metabolic state conserving energy until temperatures rise and they are energized to search for their next meal..  

Humans evolved with large brains which needed a constant blood flow, and energy supply. Along with other mammals and birds humans evolved mechanisms to maintain body temperature at a constant. Birds and mammals are termed “homeothermic” organisms. Homeotherms can continue active hunting both day and night. They can exploit both warm and even very cold climates or environments, and can more effectively metabolize foods using enzymes  to improve and speed up chemical reactions and cellular metabolism.  Enzymes work best at 20C to 35C (68F to 95F) temperatures which approximate those of most homeotherms. 

One disadvantage for homeotherms is that they need more energy than poikilotherms to survive,  since they must use a great deal of food energy to simply maintain a constant body temperature. But the physical activity advantages and enzymatic activity of homeothermy far outweighed any disadvantages. 

It is noteworthy to remind the reader here that humans evolved and spread out over the Earth during the Pleistocene Era or last Ice Age. This was a relatively unusual episode in Earth history, a time when ice sheets thousands of feet thick covered vast areas (33%) of existing continents.  Humans evolved during the last (Pleistocene Era) Ice Age, a climactic period they were well adapted to. 

Human skin functions to  modulate temperature and help keep the human body close to the near 100F (98.6F or 37 C) range. The deeper layer of the human skin (dermis) has a vast array of capillaries which can relax or constrict and control the flow of blood close to the surface where it can release body heat to the exterior  air and thus modulate body temperature.  The reddening of the skin during such events—the blush.  

Then too the skin is supplied with a vast number (2-4 million) of sweat glands. These are tiny coiled, tube-like organelles embedded in the dermal skin with a pore that opens onto the skin surface. Each gland is surrounded by a reticulum of capillaries which carry blood and which transfer water and salt from the blood by means osmosis into the gland which then moves the salty water to the skin surface. On the skin surface the water evaporates into the air and as it does, it carries away heat.

In order to change from a liquid (water) to a gas (water vapor) water in the liquid state must absorb heat energy. Gases are in a higher state of energy than liquids. Each cubic centimeter (ml) of water (about a thimble full) requires about 570 calories to make this change from liquid to gas. This energy (heat of vaporization) is absorbed  from the skin surface and used to change liquid to gas as sweat evaporates. 

You may all recall the chilling effect of wearing wet clothes.  Evaporation is a very effective means of removing heat. And the human ability to pour sweat onto the skin surface to cool itself was an essential element of human survival in the savannas of East Africa where humans evolved.  

The Kung! Bushmen of the Kalahari Desert in Botswana and South Africa use very primitive slow acting poison darts to kill game. A Lesser Kudu shot with a poison arrow will wander off and take days to die.  Kung Bushmen hunters use a method of tracking and chasing game to speed up the process and dispatch it when it falls. or more often force the kudu to flee and continue to follow closely at it attempts escape. The human hunters have an advantage..kudu have no skin sweat glands, they cool their bodies by relatively ineffective  panting and lolling their tongues as the run.  During the hunting chase in the hot Kalahari kudu  soon become overheated and collapse from heat exhaustion while the human hunters are unaffected. 

It is noteworthy to remind the reader that the water of sweat on the human skin surface evaporates fully (removing the heat) but the salts of sweat, such as sodium chloride, and acids (acetic, uric, lactic,) as well as urea are left behind. These accumulate on the skin and when left for long periods can be altered by skin bacteria to generate other compounds which can cause offense to others near-by (and also to the producer).  This is one good reason why soap was invented. Young first term male college students often forget this and are then shunned as pleasant company. Alternately depending on the level of offense these freshmen may be overpowered at night by his/her colleagues and forced into the nearest shower stall with water on full. 

But this “evaporation of water method of cooling” only works well in dry air into which water vapor can readily evaporate. If the air around the body is saturated  (full to capacity) with water vapor, evaporation is limited. At saturation (100%RH) no water can evaporate from the skin and no change of sweat into water vapor  takes place’ No body heat is lost, but metabolism must continue and heat continues to be generated..so body temperature rises. 

There is no loss of nearly 600 calories of heat energy for each thimble full of evaporated sweat! Body temperature can rise above 98.6F/ 37C and hyperthermia ensues. When body temperature climbs above 39C-40C (@ 104F) confusion, nausea, vomiting, rapid breathing, may occur.  The 

Sitting in one place in quiet air, the human body naturally evaporates water into the immediate surroundings. As sweat evaporation proceeds  a layer of saturated air tends to accumulate in a more saturated gaseous film around the body.  This close body layer of saturated air retards evaporation of sweat and the cooling process. One ancient method of relief is to employ a hand fan. The well known Spanish decorative fan used in Spain’s relatively dry and hot climate is well known.  But any way to move the saturated air away and replace it with fresh (less saturated) air will increase cooling such as the regular swing of a cowboy hat, the tiny battery operated fans one often sees in hot climes. O one can move to a more open area where currents of air will move the saturated air layer away from the skin. 

So keep cool…by encouraging evaporation of body sweat…avoid tight clothes, and most of all remember that air humidity is of almost equal importance as temperature. 

JOE’S “I’M THE GUY THAT”…SPEECH, .ABC 7/5/24

 

President's speech:   “ I'm the guy that put NATO (back) together,..”. “I'm the guy that shut Putin down. I'm the guy that put together AUKUS. I'm the guy that got 50 nations…to help Ukraine. I'm the guy that got Japanese to expand their budget. I'm the--(guy who flies ) to South Korea. I convince them to invest billions of dollars in the United States making us back in a position we're gonna own that (chip)industry again.”  President Joe Biden, with George Stephanopoulos, July 5, 2024 9:00 PM, ABC interview. 

Joe’s statement of his  “accomplishments”were  meant to prove his competency in light of his weak debate performance, in fact it only only serves to underscore and broadcast  his dangerous foreign policy failures and missteps which have resulted in an unstable, chaotic world order.

in response to George Stephanopolus’ questions President Biden did well, explaining what he considers his accomplishments over the last three and a half years. He spoke in a low whisper.  He seemed weak, and frail, yet  he answered the questions as posed. But to understand what he views as his "accomplishments" one must have more context.  

One wonders why NATO needed Joe’s attention? How did he put Putin down? Why did he have to get 50 nations together to support Ukraine? Why was AUKUS necessary ? 

He didn't put NATO "together" (it was formed in 1948-9), that was not his meaning..he implied he supported NATO and empowered it in very recent times. But why was that necessary?  President Biden’s weak foreign policy in Ukraine undermined world stability. It can be rightly stated that not only did he do nothing to encourage diplomacy in the Ukraine-Russia conflict but his lack of attention and misstatements as well as his failed polices actually exacerbated that border conflict which exploded under Biden into a world conflict. 

In fact, in January 20, 2020 Joe, well known as a gaff-prone speaker, actually may have given Putin the green light for invasion when he stated in response to a question on what the west would do if Russia invaded, Biden said; “It’s one thing if its a minor incursion, and then (we have to fight) about what to do and not do.” Thus suggesting  a minor incursion might be OK,  if Putin didn't take too much land. 

Then again in  early 2020 Joe discouraged Zelenskyy from entering into a peace initiative from Russia. The negotiations with Putin would have given a level of independence to the eastern Ukraine provinces (Doubass) and stipulated an end of Ukraine’s move toward NATO and EU membership. The fighting would have ended and negotiations commenced. President Biden —or his cabinet war hawks— preferred conflict  rather than negotiation and diplomacy. The result has been a continuing, long, escalating, catastrophic destabilizing deadly conflict in eastern Europe with tens of thousand dead on both sides, massive destruction in Ukraine, embargo of foodstuffs and agricultural products, sanctions on enemies which resulted in shortages and world inflation, and other world-wide negative implications.  

Yes!  one result of that cataclysmic development was that NATO was expanded—and Joe did encourage 50 nations to join in the defense of Ukraine.  A war which Joe  did not cause but did nothing to prevent.  Yes, Japan did increase their military budget substantially, (but this result had nothing to do with Joe's urging). 

Japan has, as other world nations, been threatened by increased world instability in the eastern Pacific.  During the Trump administration, North Korea ended its regular and threatening  missile launches into the Sea of Japan.Under Biden these acts have increased. Japan has responded to its national threats as any nation would, by more military expenditures  

But all of these “accomplishments” are the reaction to missteps of an inept administration and of Joe’s lack of attention and misplaced polices. This local conflict —a border dispute—has blow up into a major world crisis—resulting in an on-going escalating war in eastern Europe and the fear of a wider world conflict with a nuclear armed Russia.   

As a result of Biden’s years as " leader" of the western alliances the world is now divided into two nuclear armed (or potentially nuclear) camps…Russia, Iran, North Korea and China—vs— the USA and its western allies.  Joe and his incompetent staff and advisors have managed to unite  former non/threatening political and economic adversaries into a dangerous allied military front—in just three and one-half years.  

And yes one of the results of that destabilization was the AUKUS agreement. This was not a positive or optimistic sign of peace to come—but only another reminder that Joe’s policies have destabilized the world caused fear and trepidation in Australia, the UK and US (hence AUKUS). This fear, like that of Japan has  resulted escalation and rearming (in this case with nuclear submarines). AUKUS may not have been necessary in a more peaceful world focused on economic competition rather than an arms race characterized by massive expenditures on deadly nuclear weaponry and delivery systems. 

In regard to the South Korea chip factories…its true! Joe did get a chip factory built (or in progress) in Texas. But it was not a free deal. To entice Samsung US taxpayers had to fork over $6.4 billion dollars to the world’s top chip maker to build a facility for  chip manufacture in the US.

Joe’s “accomplishments” only underscore his dangerous failures and missteps in pursuit of his misguided policies which have carried the nation and the world into a time when fear dominates and drives responses. His "accomplishments" are also his abject policy failures!