The whole notion of Global Warming rests on the idea that ‘back radiation’ causes the world to get warmer as there is more CO2 in the air. The reputed measure of this proposed effect is the rise of the “Global Average Temperature”.
Generally speaking, an average of temperatures is not a temperature and has no meaning AS a temperature (and not much meaning as anything, really). This is because a temperature is an intrinsic property of one specific THING at one specific moment in TIME. It would make as much sense to talk about the average telephone number. There’s nobody at the end of that line…
But attempts to get folks to understand that point tend to founder on it being technical. Even my favorite example tends to take longer than the typical attention span in conversations.
( Two cups of water, one at 0 C the other at 40 C; mix them. What is the temperature?
You don’t know and can’t know. Is the 0 C water ice, or not?
What are the relative masses? – is one cup only 1/2 full? etc. etc.)
So I’ve sort of wandered over to the basic idea of radiative heating on a macro scale.
I’ve been trying to think of a better way to illustrate that ‘backradiation’ isn’t what sets the monthly average temperature (either globally or in one place).
I think just looking at some temperatures might make that clear, and bypass the whole physics of heat, heat of fusion, thermal mass, etc. quagmire of temperature as an intrinsic property.
With that in mind, lets look at a couple of temperature graphs.
A Trip Up The Hill
First off, I’d like to explore a trip ‘up the hill’ and inland. ALL of these locations are close enough to the same latitude that if the radiative component is what drives things, they ought to look very much the same. (They are also close enough that weather events will tend to move them in similar ways too, so watch out for that).
Let’s start at San Francisco. It is a coastal city in California with water on 3 sides. Right at the tip of the peninsula headed up toward the Golden Gate Bridge. But the SFO Airport is a bit further south and facing the bay, so not quite as water dominated.
Look it over. IF ‘back radiation’ dominates the temperatures, it ought to be rather flat, as that only changes as the CO2 and seasons change. The basic number used for Global Warming calculations in codes like GIStemp is the “monthly average” so look at the highs, and the lows, and ask yourself “Is the average of those representative of nearly constant ‘back radiation’, or something else?”
When I look at it, I notice two high temperature spikes. About the 15-16 and 27-8 dates. In between are rather long stretches of almost exactly 72 F / 21 C (that normal line). Those highs seem to land on top of times where the barometric temperature drops (just after a long high bump) and the wind loses speed.
I happen to know from living and working in and near SF that when the wind stops in the summer, it gets hot. As the inland Central valley areas get very hot, that air rises and then sucks in a cool ocean breeze over The City as the fog blanket off shore gets pulled in to cool things down again.
Looking at the lows, they seem to be just a little bit above the ‘normal’ average line. But the bulk of the tops are right AT the average line. Now the San Francisco airport has grown over the years from “nothing” prior to flight in the 1900 era to now being a few square miles of concrete, tarmac, buildings, and with tons of kerosene being burned day and night. I personally remember taking my Mum there for a flight to England (her first return in 18 years after W.W.II) in about 1963. It was MUCH smaller, the airplanes were smaller, the fuel burn was smaller, the hours of operation were fewer, etc. etc. In the years since, a huge urban area has grown up around the airport on the landward side. In short, it is a much larger Urban Heat Island than before. So I look at those lows and think “looks like UHI and concrete keeping the lows a bit higher at night”, while the daytime highs are driven by solar heating and that hasn’t changed much.
Finally, if the “highest highs” are driven by known weather events (in particular, slack wind) and typical highs are on the ‘normal’ line: What does averaging those highs and lows tell us about ‘back radiation’ and global warming?
I’d assert it tells us nothing about Global Warming (other than maybe that back radiation doesn’t matter and Global Warming isn’t…).
Taking the high and low of the month and averaging them will just tell you about how slack the winds are that month. Taking the high / low per day and averaging them will mostly tell you that a few square miles of tarmac and concrete don’t cool off as well at night as an old grass field and trees did in the past. (It will also include a little information about how many days had slack winds).
In short, I see nothing in this temperature graph that can illustrate “back radiation” changes and a whole lot that shouts about concrete and wind changes.
Averaging 6000 such graphs will not make that problem any better.
About 50 miles south, and a mile or two from the shallow end of the SF Bay, is the San Jose Airport. It, too, has had massive growth of tarmac, concrete, buildings, and traffic. It is further from the ocean with more mountains to the West, and generally warmer, dryer, and without the fog blanket.
Gee, here we see the same peaks on Aug 15-16 and 27-28. A little more muted (as the mountains and general distance from water keep us from starting from as cold a base as SFO most of the time in summer).
I find it interesting to note that the ‘lows’ here are generally tracking right along that “normal” line, while most of the highs are a bit below the normal. Most of the time we are “coloring inside the lines”. I note in passing that SFO has much more night operations than does SJC.
But in a world of “Global Warming” how can we have our hottest month be ‘a little on the cool side’? IFF “back radiation” is warming us constantly day and night all the time… how can we be a little on the cool side? The “weather” shows up in those hot day spikes on barometric pressure changes and wind changes. It isn’t “weather” causing our overall cool month… (We don’t really have ‘weather’ in the summer… mostly it’s just sun up / sun down / sun up / sun down for weeks on end). But it has been a bit on the cooler side in San Jose this summer. Not running the AC much at all.
I can hear Warmers wanting to shout “It’s just the WEATHER!!!”…. but if THAT is true, then how can averaging together 6000 stations worth of “just the WEATHER” say anything about Global Warming and “back radiation”? An average is simply going to inform you about changes in the average winds and weather…
Next, notice one other interesting thing:
All those daily temperature swings look a LOT like a ‘triangle wave’ shape. There may be some small detail not visible at this scale, so we’ll do a closeup down below, but at this granularity, it sure does seem to directly track the sun. Period. Full stop.
Think about it.
OK, so is it clouds or what? Well, no. Part of what makes California popular is that for weeks and months on end it is sunny and dry. This being a drought year, not a lot of rain going on and clouds rarely to be seen (and not much at all in August this year – we had a couple of days of rain in July, a very unusual thing and indicative of cooling). So basically this takes that whole “predicting clouds” thing off the table. But for anyone still wondering, we’ll take a look at Phoenix Arizona further down. Not a lot of rain and clouds there, either…
So the sun comes up, temperatures rise with solar angle until just overhead. Then (with maybe an hour or two lag) temperatures start back down again on about the same slope (slightly flatter) and directly tracking solar angle. Doesn’t matter if it is a colder day with a bit more wind, or one of those calm hot days. At the bottom, most days end up right back at the “normal average” line. On the 16-17 warm times, the lows didn’t make it all the way back. My eyeballing of the graph says about 10 F of extra warm at the top, but about 5 F of warm at the bottom, Yet on the 18th, right back at “normal”. So even a 10F spike over a couple of days can’t shift the bottom nor prevent the “return to the normal”. Only when still air is trapped in the bubble of our surrounding mountains and lay over a solar heated tarmac can the lows rise overnight, and at the first movement of air, BANG! back at “normal”.
How does any of that have anything to do with “back radiation”?
As the sun rises, we warm. As it sets, we cool. And as the air moves, the local heat island effects get blown away.
And averaging 6000 stations of such local effects will tell us exactly nothing about “Global Warming”.
But but but… maybe it’s the Bay that’s doing it? OK, lets go inland.
I like to look at the line from San Francisco to Reno. It passes right through Sacramento, the State Capitol, and runs about 7000 feet up the mountains to Ski Country. I’ve driven it hundreds of times. In the summer. In the snow. I know just about every turn and wiggle of that run.
Sacramento is the middle of the Central Valley. A tiny bit more north than SFO, and about 80 miles inland. That rising valley air that pulls the fog blanket over SF happens here, and a day or two after the pump starts, cooler air spills into the Central Valley from the Bay, quenching the cycle and doing a ‘reset’ for the next warm / rise / wind cycle.
Notice how the 16-17 window is also hot as is the 28-29th? About 1 day later than at SFO / SJC. Now look at HOW hot. Over 100 F / 38 C. Compare to SFO at 90 F / 32 C. There’s a good 10 F / 6 C of “uplift” in the temperatures. (Yet, oddly, the lows continue to hover about the same range… not rising nearly as much). High temperatures still arriving as the winds slacken.
What to I deduce from this? That a good 10 F / 6 C of “heating” comes not from “back radiation” nor from even direct solar heating change. It’s almost exactly the same insolation in all three places on clear summer days. What changes? The humidity.
The air in San Francisco is heavy with moisture. But the time you are at San Jose, behind the coastal mountains to the west and with the bay water further way, it is significantly drier. At Sacramento, 80 miles from water, it is quite dry in August. ( I lived there a few decades… it can be quite a desert in the Central Valley).
So to my eye, the variation in max temperatures by geography are not driven by insolation (that varies with latitude and season, that we have essentially removed by selecting for the same latitude and month), and certainly not driven by any 2nd derivative “back radiation”. They are driven by WIND variation and HUMIDITY variation.
So if wind and humidity drive the differences between locations, and radiation does not, how does averaging 6000 of them tell us anything other than that wind and humidity changed?
Has the Global Warming Cabal controlled for changes in wind and humidity? Well, no, they haven’t. We have had two major swaps of the jet stream. One in the ’70s when temperatures ‘stepped up’ in a jump, and now in the 2010’s with the ‘go flat’ (that I think would be shown a ‘step down’ but for the temperature ‘adjustments’). Those are NOT considered in the Global Warming Mantra.
And humidity they have ‘exactly wrong’. Their claim is that warming will make MORE humidity and thus more heat. Yet Sacramento is very DRY, and warmer. Same latitude. Same insolation. Same large weather systems (that come to us from Alaska in winter and from Hawaii / Mexico IFF we get anything tropical that almost never happens).
How can an average of “exactly wrong” fix it?
Now let’s go way ‘up slope’ and into the clear desert air of Nevada.
Reno has also grown a great deal over the years. As a child, when we visited, it was a wide spot in the road with some casinos. Now it is a light industrial area that has merged into a small metro-plex with Sparks and the airport has grown with it.
Here, again, the minimums run just about on the “normal” average line at, again, just about that 60 F / 16 C line. Gee, it’s almost like you put the same solar energy heat pulse into the same specific heat concrete and it only moves the earth heat mass to the same place. Then, during the day, the air can spike up and then drop down again, but the mass of the earth doesn’t care…. (“Clue Alert”…)
Daytime temps slightly over the normal line at about 95 F, but with some low spots at the start and end. Even though it is way higher in the mountains, it is only slightly cooler than Sacramento. Dry desert air and sunshine.
Again I note the generally triangle shape of the sawtooth temperatures. What is given as the sun rises to noon, is given back as it starts to set and is all gone by the morning. No ‘back radiation’ need apply. The only exceptions coming when there is a wind blowing, so opportunities to import warmer air from elsewhere, or get compression heating of air down the mountains.
Also, a question: What happened to the last 30 years of “Global Warming” heat on the morning of August 8th? Temperatures were ‘below normal’. So where is that ‘accumulated heat’ hiding? Where has it been ‘stored’ to come back on the 14th?
So if rising minimum temperatures do not tell us about “global warming heat” here, how can an average of 6000 of them say anything?
At this point it is pretty clear to me that the changes of wind and water show up in the temperature monthly graphs, and so in the monthly averages; but that radiation does not. It comes and goes on a daily sawtooth. IMHO, that makes the assertion that Monthly Average can be used to show “global warming from back radiation”, to quote one of my favorite TV shows: BUSTED!
But maybe it’s just a local California thing…
Transect Of The Nation
Let’s pick a lateral line and follow it across the nation. This is more impacted by changes of clouds and rain (since California basically doesn’t have any in August and y’all back East do…) and I’m sure some folks will want to holler “it’s just weather!!”… but if that IS true (and I think it is) then how can an average of highly variable weather indications say anything about non-weather?…
These are all major cities at about the same Latitude across the south. It would be great fun to do this for a few other latitude and even on other continents, but for a single posting, that would be way too much. So we are going to start in Los Angeles and head East. In the heart of the desert, stop at Phoenix, then move a little north to I-40 (since at that point there is no due east… I-10 cuts south east) into Albuquerque New Mexico and on into Dallas. Make a stop in Jackson capital of Mississippi, and finish in Atlanta Georgia.
Now for all these cities, the solar seasonal angle will be roughly the same, and the daily rise / set cycle roughly the same. Weather events will clearly show up in the charts, and the range and daily cycle of temperatures will say what they will.
Also by the ocean. It has been my observation that just as Seattle is about 10 F colder than SFO, LAX is often about 10 F warmer. It seems to be a direct reflection of their difference of latitude. So welcome to LA, where you can grow bananas and palm trees if you like. Also note that LAX is one of THE most busy airports in the world round the clock located in one of the largest metroplexes anywhere. Expect UHI.
We again see the 15-16 and 28-19 warm spikes. (Did I mention already that our weather tends to be the same over broad regions out here, driven by major systems out of Alaska and Hawaii / Mexico way? Makes it nice for filtering out ‘weather effects’ as comparisons don’t have a lot of ‘local weather’ during summer…)
Mostly ‘coloring between the lines’ but with a few more ‘not reaching the normal warm’ and ‘not reaching the normal cool’. LA is moderated by inland breezes off the ocean and doesn’t have the coastal mountains of San Jose nor even the small ridge between SFO and the ocean, so a small shift of wind can bring moderation, or wider swings. (And if an occasional wind from the desert inland blows out to sea, it can get darned hot…)
We again see the general sawtooth daily insolation swings in temperatures. Minimums down around 70F, or about 10 F warmer than SFO / SJC / SAC. IMHO, that is the earth staying warmer from consistently increased sunshine and less chance to lose heat in winter. i.e. latitude, not ‘back radiation’.
I also note that between the 16th and the 24th the lows dropped by several degrees, despite any ‘greenhouse effect’.
So between the daily cycle showing no significant heat storage, and the latitude confirming that it’s more about the total sun than any small gas effect, and then with the lows able to just blow down any old time to ‘below average’, even in August, in the sun, I’m not seeing where ‘back radiation’ shows up in this data.
but lets compare it with somewhere not so subject to ocean influences and wind swings.
About a 6 hour drive east of LA, in the middle of a basin in the middle of one of the hottest deserts in the world. A place I’ve visited often, and where millions have moved in retirement to escape the cold.
They grow a lot of tomatoes, wheat, lettuce, just about anything you want in Arizona. The notion that there will be less food if it gets 2 C hotter is just daft. Phoenix has year round crops. Try that in Ottawa… or New York… Or even Dallas…
Again we have a temp bump mid-month near the 15-16th and end near the 28-29th. So you will not be getting rid of those ‘weather artifacts’ on peak monthly temperatures with any kind of regional average, or grid-box, or homogenizing. Things happen over very large areas and no amount of averaging can erase the effects.
Highs generally about ‘normal’ while the lows are a bit elevated. (That, BTW, I’d attribute directly to the tarmac at the airport. I was in Phoenix one August when it hit about 125 F and they shut the airport down as the tarmac taxiways were melting and airplanes were sinking in it – only a little. Tarmac gets FAR hotter in direct sun than does sand, dirt, or even concrete. It was a few degrees cooler at all the places reporting away from the airport that day.)
At about 82 F min and 105 F max ‘normal’, warmer than L.A. (About 28 C / 40 C as I read the graph). Yet at roughly the same latitude and with the same insolation and the same ‘back radiation’. IMHO, temperatures clearly are related to wind and humidity far more than to total TOA insolation and “back radiation”.
Also note that the ‘heat’ that was in the 15-16 date highs in L.A. was not “stored” over in Phoenix during the later cool down into the 20th… So where does the “stored” heat go, eh? As the wind runs inland here, it didn’t go into the oceans…
Albuquerque, New Mexico
Both a little more north, and a little higher elevation. But not a lot further north. Also surrounded by more trees and water. (The name refers to a white oak from the region). Mountains a bit cooler than desert valleys.
Remarkably similar, if more muted. A small dip where the others had dips, small rise middle and end of month. Daily triangle shape to the temperatures. Lows generally riding the minimum line average, highs usually ‘inside the lines’ but with a couple of wind driven warm days. Being part way in latitude between L.A. and SFO it has a minimum average right between them… probably a ‘dig here’ on showing the latitude / minimum average relationship stability around the globe…
I’m going to pick up the pace a little here as I think folks know what to look for by now. So lets look at Dallas, next over on this line.
Giant airport surrounded by dozens of miles of urban metroplex. The very definition of MegaCity and Urban Sprawl. It can take 1/2 a day to drive from the edge on the Dallas side past the airport and over to the other side of Fort Worth. (And that is pushing it… there are 2 circles of ‘ring road’ added to bypass it over the years as things have grown. UHI here is immense.)
Weather in Texas can come down from Canada, up from Mexico, or blow in from the Gulf. It is more variable than the western block. But we didn’t have a Canada express or a hurricane this August.
Oddly, Wunderground would not produce ‘normal’s lines on this graph. I’ll try again some other day and see if I can get it updated. For now, it is what it is:
To my eye, minimums generally running just about the same 80 F or so as Phoenix. Maybe a touch cooler. Looks about 3F to 5F to me. Daily sawtooth pretty regular, and swings to min / max more tied to wind events than to any change of ‘radiation’. Note in particular the dip on the 20th during a windy patch. While the other days all show zero precipitation, those days are different:
19 95 80 68 73 68 60 87 63 45 30.01 29.84 29.70 10 10 5 22 13 30 0.25 Rain , Thunderstorm
20 75 70 64 68 65 59 88 81 73 30.04 29.98 29.92 10 9 2 15 6 22 0.20 Rain
So rain and wind (22 mph to 30 mph on the 19th) set the cool pattern days. Sunshine and clear sky the warm ones (when the wind doesn’t blow especially).
So, once again, what does an “average of weather driven events” say about “back radiation warming”? I’d assert “nothing”. Which means ALL the “climate products” built on these monthly average temperatures are a farce. They, are measuring, at most, average changes of wind patterns and water (as humidity or rain), and nothing about CO2 or “back radiation”.
Let’s skip on over a State or two into the Gulf influenced humid south…
(Yes, I know y’all know what State Jackson is in and that it’s the capitol, but they made me learn how to spell Mississippi in grammar school so I’m damn well gonna use it when I have a chance… ;-)
Flat, green, humid, wet, and hot. Not as bad as the swamps of Louisiana, but close…
Another one without ‘normals’ lines…
Running along about 75 F to 95 F ( 24 / 35 C ) with high and low excursions driven by wind and weather and water, ‘radiation’ not so much.
So tell me, even if there were a 1/10 C rise from CO2 on, say, the 15th, didn’t that all just get flushed out on the 17th thunderstorm day as the water rose to the top of the troposphere and radiated heat skyward, then falling as precipitation. Gone in a flush of ‘heat of evaporation’… And certainly was gone after the 27th when more rains the week before had time to evaporate.
( Details on that are down in the bottom of the “monthly” data at Wunderground.)
The point here being pretty simple. It looks like the “min” average or normal is set by latitude (sun angle) and season mostly, with some influence from altitude and some moderation by nearby cool water. Swings in min and max vary with weather, wind, humidity, wind, precipitation, wind, and did I mention changes in wind direction, strength, and barometric pressure? Nowhere in that list is “back radiation” as it has zero influence on the monthly Min / Max values, so can have zero utility in any of the models and ‘global temperature’ calculations based on those monthly averages of weather.
And now, before I completely thrash this mortified equine… On to the last stop, Georgia.
Influence from the warmer Atlantic (rather than the cold North Pacific or the hot Gulf) and enough inland to be reasonably free of ocean whims on most days, but still not an inland desert.
And, yes, another urban Metroplex with massive growth history and undoubted UHI / Airport Heat Island influence.
Mostly “coloring inside the lines” so essentially dead normal.
The hot 2-5th happen when the wind dies down. The cooler 17-20th in fog and thunderstorms.
17 86 79 71 75 72 71 0 0 0 30.17 30.09 29.99 10 9 1 30 3 40 0.32 Rain , Thunderstorm
18 87 79 71 76 73 71 100 85 70 30.10 30.00 29.88 10 8 0 24 5 30 0.96 Fog , Rain , Thunderstorm
19 88 80 72 75 74 72 100 82 63 30.03 29.97 29.91 10 8 1 14 5 17 0.52 Rain , Thunderstorm
20 88 81 73 75 73 70 100 80 59 30.06 29.99 29.93 10 8 0 14 5 20 0.33 Fog , Rain , Thunderstorm
Once again, water brings cooling, still air warming. So any average of min-max averages is really a proxy for changes of water and wind, not of CO2 and any “back radiation”.
What all the “Warmest EEEEVVVVAAAAAhh!!!!” histrionics really indicates is that the last few decades of the 20th century were a little dryer and less windy. But anyone who paid any attention to the weather already knew that as the Jet Stream had gone flat in the early ’80s. And now it has returned to the ‘loopy’ form and we have a lot more wind events going on.
( I’ve commented on that shift before, but not in this context).
The ‘min’ is generally running along a 70 F line; or about the same as Los Angeles. Gee, nearly 3000 miles of distance, and entirely different oceans and weather contexts, and the dirt and sun still set the normal average minimum… Might lead a fella to think that the specific heat of dirt and average insolation warming it are all that really matters long term.
And DO note that it is generally ON the average; well, if you ignore that big cold dip late in the month…
And that concludes our transect of the nation. I’m just going to put one more graph up here. It is a ‘zoom in’ on a daily cycle.
How Triangular The Day?
I can’t think of anywhere more suited to study of how solar radiation (and any reputed “back radiation”) influences the temperature of a place than the middle of the Desert Southwest of the USA. Sure, the Sahara might work better, but how good the instruments? Maybe Australia, but the BOM has done what to the data? So we’re going a little south of Phoenix. To Tucson.
It’s a medium sized town that has had growth, but is still modest in size. Not a lot of international flights taking off at 2 AM. It gets summer rains (so a similar graph from December might be better) but I’ve selected this slice of time from a dry part in between summer showers. Just how “triangular” a saw tooth is a given day? Is the shape more interesting than that?
I find the shape interesting and informative for several reasons. First off, it isn’t just a triangular shape. Up and down are NOT symmetrical. Nor is it a sine wave. Temperatures rise fast with the onset of solar heating. You can see sunrise in the data. Then, after sundown, an almost linear decline in temperatures into the night.
Yet it flattens out late at night / early in the morning. The daily heating is essentially stabilized with the night and ‘goes flat’ before sunrise.
The solar gain and the early radiative loss are almost equal in size and slope, and with time left over at night for further cooling, if only the rocks could conduct heat to their surface and radiate that fast.
To me, this says that even in the Summer, in the middle of the Desert Southwest, near the longest day of the year, there is plenty of time for the air and land surface to radiate away to space all the daily heat, until the land surface has reached a balance point. Any ‘retained heat’ is down far enough into the rocks and sand that it can not radiate to space. It would need to conduct back to the surface of the dirt and rocks first. It is the ratio of time for heat to “diffuse into the dirt” vs “diffuse out of the dirt” that cause seasonal warming and cooling. The air and surface layer reaches balance each night.
The daytime peak does not have a flat spot (nor do some of nights, but even those without a flat have a ‘go flatter’) showing a directly solar driven heat gain, and a roll over at just past peak sun. I suspect looking at this on an hourly basis could even tell you the thermal lag of the dirt /air system and let you calculate how much heat gets stored into the dirt. I can also say from personal experience that it is NOT the air warming the rocks. Sun on desert rocks and sand makes them very hot. That then puts some of the heat into the air, while the other soaks into the rocks. Very much like the lunar surface. IMHO the major determinant of air temperature averages will be the latitude, altitude, and surface type. There will be minor modulations from water changes (“weather”) and from wind shifts (“weather”). And CO2 has no role in it.
That’s what I see in these graphs.