fredag 31 januari 2020

Atmosphere Effect of 33 C vs Radiation Effect of 9 C

Greta's Vision: Transforming the Earth into a green planet.
A recent post gives evidence that the so called greenhouse effect as the total effect of the presence of greenhouse gasses in the atmosphere of the Earth is +9 C, rather than the claimed +33 C as the corner stone of CO2 alarmism asking for a new fossil/carbon free society and a complete restructuring of human civilisation.

The +33 C comes from an idea that the infrared radiation from the Earth with its atmosphere into outer space at 0 Kelvin, takes places from an effective emission level of 5 km above sea level at a temperature of -15 C. This fits with a lapse rate of 6.5 C/km as en effect of both thermodynamics including gravitation and radiation.

Out of the 340 W/m2 received from the Sun, 240 W/m2 is absorbed by the Earth + atmosphere and so has to be radiated to outer space at 0 K, which according to Stephan-Boltzmann's law for a black body corresponds to a temperature of 255 K, thus defining the effective emission level to be 5 km.

The +33 C then comes from comparing the temperature of 255 K at the effective emission level with the temperature on the surface of the Earth of 288 K, and the difference is then proclaimed to be the greenhouse effect as 33 = 288 - 255 C.

But this is not correct, because it attributes the total effect of the atmosphere, being an effect of both thermodynamics and radiation, to radiation alone. But there are strong arguments that the total effect is 2/3 thermodynamics and 1/3 radiation (in any case without domination of radiation), which fits with the idea of +9 C as the effect from radiation alone, which is what should be called the greenhouse effect, if rules of logic are followed.

By identifying a total atmosphere effect with a radiation effect, a large greenhouse effect of +33 C comes out. Correcting this fundamental mistake reduces the greenhouse effect by a factor 3 and thus changes alarm into no-alarm.

The dooms-day vision of CO2 alarmism can thus be replaced by hope of a better future for in particular all poor people of the world, who would have no place after the complete restructuring. Recall Greta's answer to the question of what has to be changed according to climate alarmism: Everything!

With a greenhouse effect of +9 C the surface temperature of an Earth without greenhouse gasses would thus be + 6 C, which incidently(?) is the mean annual temperature of Sweden! This supports a widespread idea that Sweden is country of mean values and as such the right norm.

Annual mean temperature in Stockholm recovering from Little Ice Age from 6  to 7 C.
As high temperature in 1930s as today. Variation from year to year 4 C.

måndag 27 januari 2020

Boeing 737 Max: Perspective and Questions

The BNP of Sweden is about 500 billion USD, and that of the US 18 000 billion USD, about 40 times as big reflecting a population of 10 million in Sweden and 300 million in the US.

Today nearly 1000 Boeing Max are grounded each one selling for 100 million USD with a total of 100 billion USD grounded, about 20% of the BNP in Sweden and 0.5% of the BNP of the US.

The yearly revenue of Boeing is about 100 billion and the total stock value 200 billion USD.

  • Will the Max ever fly again? What happens with Boeing if not? If half of the total value is lost? 
  • Why did the Boeing engineers design an airplane which showed to have a tendency to stall? 
  • Was it because they used standard CFD (computational fluid dynamics) software which could not predict stall?
  • What new CFD software will be required to get the Max in the air?
PS Boeing 797/NMA Is Going Back To The Drawing Boards:
  • Boeing has shelved all of its plans for the ‘797 NMA’ and has been asked to return to the drawing board by its new CEO.
Will the 737 Max also be returned to the drawing board?  Compare with this post.

tisdag 21 januari 2020

The True Total Greenhouse Effect is +9 C, not +33 C

Misconception: Without greenhouse gasses the Earth would be a frozen snowball at  -18 C.
What is the warming effect of the radiative action of the Earth atmosphere on the temperature of the surface of the Earth, the so-called greenhouse effect?  See also following post and this one.

What would thus the temperature be if the atmosphere was fully transparent without the so-called greenhouse gasses water vapour and CO2, thus without effects of (infrared) radiation? This would be like an Earth with no atmosphere.

And the other way around: What would the temperature be if the atmosphere was fully opaque?

These questions connect to earlier posts such as this, and these if you want to browse. For a revelation of the mystery of black body radiation, see the web site Computational Black Body Radiation.

The standard answer propagated by global warming alarmism is that the greenhouse effect is +33 C. It is claimed that with a fully transparent (or no) atmosphere, the Earth would be a frozen ball at -18 C instead of the observed +15 C with a difference of 33 C. 

The presence of greenhouse gasses is thus what makes the Earth livable. The message is that the greenhouse effect is big = 33 C and as such will lead to dangerous global warming of 3 C upon a small increase of CO2 as the "best estimate" of IPCC, as 1/10 of an estimated big greenhouse effect.

This is the very basis of climate alarmism demanding a stop to emission of CO2 to prevent the Earth + atmosphere passing a tipping point into a run-away greenhouse effect approaching the surface temperature of Venus with its atmosphere filled with CO2, that is a roaring Hell at 462 C.

This is the apocalypse waiting unless we cut down CO2 emissions from human activity to zero and form a fossil free world following the lead of Sweden now transforming into the first fossil free welfare state as required by the New Swedish Climate Law.

To check the alarm signal of 33 C let us recall Stephan-Boltzmanns radiation law for a grey body:
  • $Q = \epsilon\sigma T^4$
connecting radiance $Q$ at temperature $T$ in Kelvin K into a background at 0 K, through Stephan Boltzmann's constant $\sigma$ with $0\le\epsilon\le 1$ a coefficient of emissivity with a black body characterised by $\epsilon =1$.

Assuming absorptivity=emissivity (according to Kirchhoff's law), we can use the SB-law to compute the temperature $T$ of a grey body at a certain distance $D$ from the Sun knowing that the temperature $T_S$ at the emitting surface of the Sun (acting like a black body) is 5778 Kelvin K. What is needed is the ratio $q=R/D$ with $R$ the radius of the Sun, with $q^2$ the dilution effect depending on distance/area. All grey bodies at the same distance from the Sun would then have the same surface temperature (compare with discussion here).  

For the Earth $q =0.00465047$ which gives the surface temperature $T_E$ through the following formula resulting from the above SB-law:
  • $T_E = (0.25*q^2)^{0.25}*5778 = 279$ K
with the first factor $0.25$ the ratio between projected surface to total surface of a sphere. The temperature of the Earth as a grey body with fully transparent (or no)  atmosphere, would thus be 279 K or +6 C.

For Mars with a very thin almost transparent atmosphere and with a distance to the Sun equal to 1.524 astronomical units, the formula gives 225 K, to be compared with observed about 228 K with then a small 3 C greenhouse effect. The two small moons Phobos and Deimos of Mars are reported to have about the same temperature of 233 K.  

For Mercury essentially without atmosphere with a distance to the Sun of 0.4 au, the formula gives 440 K, just as observed with zero greenhouse effect.

The mean value of max and min temperatures of Ganymede, the largest of Jupiter's moons with a very thin atmosphere of Oxygen, is -125 C, which fits well with the formula with a distance of 5.2 au, again with zero greenhouse effect.

For Titan the largest moon of Saturn at a distance of 9.6 au the formula gives 90 K to be compared with an observed surface temperature of 94 K, thus with a very modest greenhouse effect of 4 K from an atmosphere somewhat denser than that of the Earth consisting mainly of nitrogen.  

For Pluto with average au = 40 the formula gives 44 K = - 229 C in agreement with observed temperature varying between - 223 and - 233 C.

For the Moon (without atmosphere) rotating once every month, it is more natural to use the formula with the factor 0.25 replaced by 1 representing maximal (instead of mean) temperature to get +121 C fitting fairly well with observed maximal temperature  +127 C.

We thus see that the formula works (surprisingly or not) very well for Mercury, Mars, Ganymede, Pluto and the Moon essentially without atmospheres, and so we may expect it to serve also for an Earth without atmosphere: 

The recorded mean temperature on the Earth surface is 288 C with gives a total atmosphere effect of +9 C, from fully transparent (or no) 279 K to observed 288 K with greenhouses gasses present into a semi-opaque atmosphere.

The total greenhouse effect is thus at most 9 C, instead of the 33 C as the corner stone of global warming alarmism.

The observed greenhouse effect of 9 C would then represent an observation of the total effect of the atmosphere on surface temperature, including both radiation and thermodynamics with gravitational lapse rate. Observation and not speculation.

Of course, the assumption that for the Earth without atmosphere emissivity=absorptivity, can be debated, since absorption and emission occurs at vastly different light frequencies, but yet may serve to get a rough estimate of the greenhouse effect (with Mercury, Mars, Ganymede, Pluto and the Moon essentially without atmospheres as observational support of the formula).

The temperature 255 K (-18 C) behind 33 C comes from an application of the SB-law assuming absorptivity = 0.7 and emissivity = 1 with questionable logic.

We can go one step further and predict what the temperature $T_E$ would be with a fully opaque
atmosphere by extrapolation from the present observed situation with the "infrared atmospheric window" acting as fully transparent atmosphere letting through 1/6 of the total emitted (infrared) radiation from the Earth surface directly into outer space. Closing the window from 5/6 to fully shut into a fully opaque atmosphere could then have an effect of $9/5$ C, less than 2 C. This is the observed variation of temperature after the last ice age. 

The ultimate effect of making the atmosphere fully opaque would thus be less than 2 C and so the possible effect from more CO2 would thus be much smaller. 

This argument thus supports an idea that climate sensitivity as the temperature increase upon doubling of CO2 from preindustrial level, is less than 1 C. This is based on observation of temperature 288 K (15 C) and atmospheric window 5/6 shut combined with the SB-law. Pretty basic and undisputable.

One can argue that the observations used in the argument include "feed-back" (from convection and evaporation). This is  to be compared with another common argument based on (invented) "radiative forcing without feed-back" as 1 C, which is inflated to 3 C by free invention of thermodynamic feed-back. 

We can see the reduction of the basic greenhouse effect from 33 C to 9 C with a factor of 3-4, as a
reduction of the "best prediction" of climate sensitivity by IPCC of alarming 3 C into non-alarming 1 C. It may be as simple as that, to give the hope back to the people of the world. 

PS1 In recent work by Nikolov and Zeller (referring to work by Volokin and ReLlez) the greenhouse effect is claimed to be whopping +90 C. A coming post will explain the origin of this utterly alarming  (misleading) number. Nikolov and Zeller do not start out very promising: Thermal enhancement of 90 K creates a logical conundrum...appears inexplicable..Stay tuned...

PS2 The infrared atmospheric window is indicated in blue in the following picture:   

PS3 The thick CO2 atmosphere of Venus is fully opaque, while the very high surface temperature of +462 C is a thermodynamic effect of high pressure from gravitation and not any "greenhouse effect" from CO2.  For a Venus without atmosphere the grey body formula gives +60 C. 

söndag 12 januari 2020

On Real Simulation

The painter, the painting and the nude physical origin.
Icarus Digital Math will be launched under the banner:
  • automated real simulation. 
Here "real" signifies that the simulation can serve as true prediction of reality and "automated" that the key elements of the simulation
  1. mathematical modeling in terms of differential equations
  2. discretisation in terms of algebraic equations
  3. computational solution of algebraic equations, 
are carried out in the form of computational software, such as FEniCS. 

The term "real simulation" may seem like an oxymoron with an apparent contradiction between reality as ”what is” and simulation as ”what is computed/imagined”. But the relation between reality as god-given physical origin and simulation as man-made mathematical model or picture, is in fact very complex and as such an important aspect of both science and arts. 

The postmodernist philosopher Baudrillard coined the concept of ”hyperreality” with the image filling the empty place of a non-existing origin, as true reality with Disneyland as example. 

The computer scientist Dijkstra similarly elevated the model as the "abstract machine" more true than the "physical machine": 
  • Originally I viewed it as the function of the abstract machine to provide a truthful picture of the physical reality. Later, however, I learned to consider the abstract machine as the true one, because that is the only one we can think ; it is the physical machine's purpose to supply a working model, a (hopefully) sufficiently accurate physical simulation of the true, abstract machine.
It also comes to full expression in the Copenhagen Interpretation of Quantum Mechanics with the observer intimately coupled with the observed reality, in particular deciding the fate of Schrödinger's cat in the process of observation. 

In arts, the relation between the painter, the picture and the model is also filled with deep meaning, connecting to Plato's allegory of the cave with shadows forming the reality. 

onsdag 8 januari 2020

Boeing Flight Simulator?

The Guardian reports:
  • Boeing now recommends 737 Max flight simulator training for pilots.
  • Decision is a reversal of company’s long-held position that computer-based training alone was adequate.
In order for a flight simulator to correctly prepare pilots to handle real flight, the simulator must represent reality, which requires CFD (computational fluid dynamics) software capable of predicting the real reaction of the airplane upon control input from the pilot, including the critical phenomenon of stall which must be avoided. Standard CFD does not have this capability since it is based on prescriptive modeling.

Without CFD the action of an airplane, beyond simply guessing, will have to be discovered from extensive experience in real flight, where extreme situations such as stall are hazardous to test and thus must be avoided.     

DFS Direct Finite Element Simulation is new CFD software based on first principle physics without prescriptive modeling, which has shown to be truly predictive of complex flight dynamics including stall, beyond the capability of standard CFD.    

The design debacle behind the two 737 Max crashes can be connected to the use of standard CFD without stall prediction.

The question is now if Boeing is going to use DFS to design the intended upgrade of the automatic stall prevention system MCAS and the flight simulator preparing pilots to handle 737 Max with MCAS. Or if Boeing will continue to rely on standard software without stall prediction.

See also: Boeing employees’ frightening internal messages released in 737 Max investigation:
  • Would you put your family on a Max simulator trained aircraft? I wouldn’t.
  • This airplane is designed by clowns who in turn are supervised by monkeys.

lördag 4 januari 2020

Automated Flight Based on Predictive Flight Simulation

WSJ reports:
  • MAX Crashes Strengthen Resolve of Boeing to Automate Flight. 
  • Boeing, Airbus and industry experts for long have planned more technology to prevent pilot error.
  • Boeing Co. is increasingly committed to transferring more control of aircraft from pilots to computers after two crashes exposed flaws in an automated system on its 737 MAX that overpowered aviators in the disasters. 
  • Executives at Boeing and other makers of planes and cockpit-automation systems for some time have believed more-sophisticated systems are necessary to serve as backstops for pilots, help them assimilate information and, in some cases, provide immediate responses to imminent hazards...
Jetliners have auto-pilot systems relieving pilots from routine flight control when cruising, while a fighter jet like the JAS Gripen requires automatic control to handle the built-in instability allowing quick turns. 

An auto-pilot is like a cruise-control on a car set to maintain a given speed as an option for steady cruising, without true capability to replace the pilot under variable conditions. Not so sophisticated. 

The forward canard of JAS Gripen is used to automatically stabilise the flight, which is too delicate for manual pilot control. The interaction between the pilot and the control system carries the danger of PIO pilot induced oscillations, which caused two early JAS crashes before the software was tamed to slower turns. 

The two Boeing 737 Max crashes were caused by the MCAS control system installed to help the pilot  stay away from stall in climb at full throttle after start by automatically pointing the nose down upon input from a single angle of attack sensor. But the sensor failed and MCAS forced the plane into the ground. Not so sophisticated.

So, Boeing is now searching for "more-sophisticated systems to respond to imminent hazards" in different forms of automated flight.     

Development of automated flight would be greatly helped if predictive computational simulation of the dynamic action of an airplane from controls including throttle, rudder, elevators, slats, flaps and spoilers, was possible, since it could replace difficult time-consuming real flight testing. 

Standard software for CFD Computational Fluid Dynamics is not truly predictive, since it hinges on wall and turbulence models, which are prescriptive rather than predictive, and thus do not well serve this purpose. 

But there is light in the tunnel (for Boeing): DFS Direct Finite Element Simulation is new unique CFD software offered by Icarus Digital Math allowing prediction of the full dynamic flight characteristics of an airplane from first principle physics, without wall and turbulence models. 

DFS thus opens the possibility to construct a flight simulator based on first principle physics, which is truly predictive and as such can contribute to the development of (safe) automated flight.