From Dr. Roy Spencer’s Global Warming Blog
by Roy W. Spencer, Ph. D.
…but the coolest summer nights have warmed by 5 deg. F.
John Christy and I continue to examine U.S. air temperature trends, especially those in summer, and John has recently been looking at “heat wave” statistics.
My interest is in determining how much the urban heat island (UHI) effect has impacted reported warming trends. Last year we published a paper using population density as a proxy for urbanization, and found that about 60% of U.S. urban and suburban warming trends in Tavg (the average of the daily maximum [Tmax] and minimum [Tmin] temperatures) since 1895 in the “raw” (non-adjusted) temperature data could be accounted for by urbanization.
But we also found that relationship largely disappeared by the 1970s, with little warming since then being accounted for by increases in population density.
Landsat Impervious Surface Data
We used population density in that study because the datasets are global and extend back to the 1800s (and even earlier). But the most direct physical relationship to UHI warming would be the coverage of the area around the thermometer by impervious surfaces (IS). Those data are now available at 30 meter resolution from Landsat for each year between 1985 and 2024 (40 years). IS might well reveal UHI effects in cases where population density is no longer increasing but wealth has increased (more air conditioning, Dollar Generals, etc.)
But I’m not going to show IS data today, that’s for another time. I’m only explaining how I got here.
D.C. Urban Warming Trends: The Difference is Like Day and Night
For now I’m examining metro areas (which is what the EPA Heat Wave papers also do), using airport ASOS measurements which is what the National Weather Service and FAA mostly rely upon. These systems are well-maintained since their primary purpose is to support air traffic safety.
I started with the center of America’s universe, Washington D.C. And I also decided that something better than a “heat wave” index was needed.
The heat wave (like pornography) is difficult to define, but you know it when you see it. How many days in a row constitute a heat wave? And how hot do those days have to get? Above the 85th percentile? 90th percentile? Those questions do not have definitive answers.
Also, by choosing a binary variable, there is no gray area available for days that are almost a heat wave (oh, sorry, there were only three days above 100 deg. F, so you didn’t meet the 4-day threshold). Such definitions lead to dodgy statistics, such as computed trends in heat waves,
So, I decided (as a meteorologist) that the hottest days in each month make more sense to keep track of for climate trends. I decided on the average of the 3 hottest daily maximum temperatures in each summer month (June, July, and August) as a potentially useful metric, which is approximately the hottest 10% of the days in the month. This metric always exists, every month, every year, and it always has 3 days. This is good for statistical analysis.
But then I thought, why stop there? What about the 3 coolest Tmax days each month?
Which then led to, “What about the warmest and coolest 3 days minimum temperature (Tmin) measurements?”
So, I started with Washington D.C., Reagan National Airport, which is used by your favorite congresspersons and presidents (as well as the public) to keep track of how hot it’s getting.
The results surprised me. Here are the temperature trends in those different categories. What is amazing is that the coolest summer nights in DC have warmed 10 times faster than the hottest summer days:
In fact, the trend in the hottest days’ temperatures is not even statistically significant, at only +0.12 deg. F per decade, which is just under a total of 0.5 deg. F warming in the last 40 years. No Boomer would notice that in their lifetime.
But look at those nighttime temperatures! The coolest nights have warmed by almost 5 deg. F in the last 40 years. This is clearly dominated by the UHI effect, since climate models tell us that days and nights should be warming at much closer to the same rate.
Now, Washington D.C. might be an outlier for urban areas. I’m just starting down this road, so we shall see. But I’ll bet most people would not have expected these results if they have been watching the local D.C. TV stations’ weather and news coverage.
This is similar to the observation in north-west Europe that the summers have not become noticeably warmer, in spite of the annual hype about ever more ‘heatwaves’, but the winters have slightly.
Same is true on this side of the pond NOAA’s Climate at a Glance shows that the warm part of the year April – October Min & Max temps show the least warming trend and the cold time of the year November – April trends show the highest warming trend:
Forgot to add in the IPCC link:
IPCC AR4 Chapter 10 Page 750 pdf 4
Temperature Extremes
It is very likely that heat waves will be more intense,
more frequent and longer lasting in a future warmer climate.
Cold episodes are projected to decrease significantly in a
future warmer climate. Almost everywhere, daily minimum
temperatures are projected to increase faster than daily
maximum temperatures, leading to a decrease in diurnal
temperature range. Decreases in frost days are projected
to occur almost everywhere in the middle and high latitudes,
with a comparable increase in growing season length.
Looks like the first part of the paragraph is out of step with the second part.
“How many days in a row constitute a heat wave? And how hot do those days have to get?”
Why not stay with what they used to use ???
5 days , 9 F or more above average .
Quit moving the goal posts !
Not moving the goalpoasts. Using continuous data like Spencer did provides more detail than artificial binary cutoffs. Otherwise you get cases where the temp hits 99.8° for 10 straight days and it’s not a heat wave which is silly.
Binary cutoffs also allow the attribution folks to say climate change made heat waves 5x more likely when all the temperature did was go from 99.8° to 100.1° past a supposed cutoff.
https://ourworldindata.org/grapher/heat-wave-index-usa
Look at the record .
Heatwaves DOWN .
Precisely what is to be expected if the heat source making thermometers hotter is anthropogenic heat. This leads the ignorant and gullible “climate scientists” to believe that “the climate” is becoming hotter, as they are besotted with meaningless “averages”.
Fairly obviously, an increase in minimum temperatures will lead to a higher “average” of maximum and minimum temperatures.
Just the anthropogenic waste heat contribution, only noticeable in the absence of sunlight, and more noticeable in areas of dense population, relatively slow air movement etc.
Or you could believe some charlatan claiming that CO2 makes thermometers hotter, in some mysterious and magical way which is too difficult to explain.
No extra hot summer days and fewer cold winter nights. What is not to like!
I’d be willing to bet you could get great correlation with electric consumption and nighttime temperatures. Be prepared for jokes about “Hot on the Outside, Cool on the Inside.”
Very nice Dr. Spencer. What I appreciate most here is that you communicate in such a clear and understandable manner. Thank you. Another consideration would be that this could also show the effects of CO2. CO2 doesn’t warm the planet it slows down the cooling. Slowing down the cooling would seem to increase nighttime minimums would it not?
Harold The Organic Chemist Says:
RE: The Greenhouse Effect
RE: H2O vs CO2
At the MLO in Hawaii, the concentration of CO2 in dry air is currently
427 ppmv. One cubic meter of this air has a mass of 1.29 kg and contains 0.84 g of CO2 at STP.
In air at 70° and with 70% RH, the concentration of H2O is 17,780 ppmv. One cubic meter of this air has a mass of 1.20 kg and contains 14.3 g of H2O and 0.78 g of CO2. To the first approximation and all things being equal, the amount of the greenhouse effect (GHE) is given by:
GHE = moles H2O/moles H2O+moles CO2/0.79/0.79+0.012 =0.98 or 98%
This trace amount of the greenhouse gas CO2 in air can absorbed only very small amount of out-going long wave IR light which can heat up such a large mass of air by a very small amount if at all.
This empirical data falsifies the claims (i.e., lies) by the IPCC that CO2 cause global warming and is the control knob for climate change. Please keep in mind that about 71% of the earth’s surface is covered by H2O.
And air, like anything else, promptly cools if heated above surrounding environmental temperature.
Resulting in cooling in the absence of sunlight – not heating. Slowing the rate of cooling does not result in heating. That’s a fairytale believed by the ignorant and gullible – and “climate scientists”, of course.
Nobody ever accused a “climate scientist” of being too intelligent, did they?
Slowing the rate of cooling, results in air that is warmer than it otherwise would have been.
Nonsensical misleadingword salad. Slowing the rate of cooling does not result in heating. Go on, tell me you weren’t trying to imply that adding Co2 to air makes it hotter!
You were, weren’t you?
You really need to work on your reading comprehension. I said nothing about heating.
Mark, are you implying that warming is not the result of heating, or that recorded temperatures are not due to warming?
Keep playing semantic games – you’ll lose. Sorry about that.
You are assuming that each molecule of CO2 can absorb one and only one photon.
That’s not how it works.
A molecule of CO2 captures a photon, then almost immediately passes that energy to another molecule via collisions. It is then ready to capture another photon and pass it’s energy along. Each molecule of CO2 does this millions of times per second.
“You are assuming that each molecule of CO2 can absorb one and only one photon.”
Ah, here’s our deluded and hypocritical physics professor again. How’s that definition of the Second Law of Thermodynamics that I asked you for coming along, Professor?
And has been explained to you dozens of times, the 2nd law doesn’t apply to radiation.
Are you really stupid enough to think that a photon remembers what the temperature of the molecule that emitted it was?
“the 2nd law doesn’t apply to radiation.”
Who told you that? It wasn’t a physicist. Please describe the 2nd Law for us, if you would be so kind.
“Are you really stupid”
I’m not the one who can’t describe the 2nd Law, am I?
Actually it wasn’t just a physiscist, it was a physics book and entire physics course.
I have described the 2nd law, it’s you that refuses to accept that your ignorant opinion is so wrong it fails to reach laughable.
“I have described the 2nd law”
Where? I must have missed that. Can you point me to where you described it, please? Which physics book told you that the 2nd law does not apply to radiation? None of mine told me that.
What’s the matter, Professor? Cat got your tongue? Ran out of stupid things to say, so you’re just going to insult me and run away? Who raised you to behave like this? How old are you, anyway? I hope your parents are proud of you. It doesn’t look like anyone else is.
Let me guess, you took one course in “Dumbed-Down Physics for Engineers” and now you think you’re a physicist, is that it? Well, you’re not. Everything they told you in that course was, unfortunately for you, a combination of “engineering approximations”, half-truths, and outright fabrications. You’re going to need to study a lot harder than that before you can pass yourself off as a physics professor. The rest sure had to. Whom do you think you are fooling?
If by chance you actually have enough brains to attempt to answer my question properly, the definition you’re looking for will start like this: “The Second Law of Thermodynamics states that <X>”. It’s right there on Wikipedia. You can find it with about two seconds of googling. Please paste the answer here.
Whoa! A long winded ad hominem is still worth nothing more than a simple “wrong”. That means it is worth zero in refuting anything!
“refuting anything!”
Please feel free to help MarkW out with his definition. He’s having an awful lot of trouble with it.
It really is sad how tightly ignorant people cling to their ignorance. Getting more and more angry at those who point out their ignorance.
The second law applies to heat flow. That is two objects that are in contact.
You can describe what you think the second law is Unfortunately, your description has no bearing on the 2nd law.
I have described the 2nd law. The problem is that my description doesn’t match your incredibly ignorant opinion of what it should be.
“The second law applies to heat flow”
That isn’t the definition that I asked for, is it? Of course not. Try again.
“You can describe what you think the second law is”
I’m the one asking the questions. Please answer them.
“I have described the 2nd law”
No you haven’t.
Try this: type “second law of thermodynamics” into Google, and paste here the first answer that comes up. Or the second, if you prefer.
For various reasons I won’t be able to reply here for a bit, so we’ll probably have to follow up in another thread later, since the comments here will be closed soon, and it takes much longer than that to teach physics to an engineer. However, my silence does not mean I have forgotten about our physics lesson.
Remember, as I told you before (obviously it went in one ear and out the other, with a big gap in the middle), you’re looking for a definition that starts with a phrase like this: “The Second Law of Thermodynamics states that <X>”. That’s science. Not engineering. I know, square peg into a round hole and all that, but give it your best shot anyway.
Note that telling us “the 2nd law applies to heat flow” is, of course, totally irrelevant. You would get an F on your physics test for that. It’s no better than asking for a definition of a wheel, and being told that a wheel applies to cars. That tells you absolutely nothing about either wheels, or cars. You can do better. I have complete confidence in you. <cough>
“your incredibly ignorant opinion”
Let’s discuss whose opinion is “incredibly ignorant” after you’ve shown us the official Google definition, or any other online or printed textbook definition of your choice. Go ahead and do that now. I’ve given you instructions that a six-year-old could follow. Or even a well-trained chimpanzee, for that matter. Can you do it?
Probably as stupid as you thinking that a rifle bullet moving at 800 m/s knows it is not sitting still, but has been fired.
You really have no clue, do you? Go on, tell me you understand why a photon has no rest mass, but possesses momentum. Then use your superior intelligence to explain why it is impossible to accurately establish a photon’s momentum and position simultaneously.
Are you really stupid enough to believe that a photon knows whether you are trying to measure its momentum or position?
Still completely irrelevant to the question being discussed.
Photons are mathematical constructions. The basic definition is the quantum of energy needed to raise the valence state of an electron.
Photons have no size and zero rest mass. Electro magnetic waves are not the output of a shot gun.
In addition, the EM energy absorbed is not kinetic. It is potential energy. It does not transfer on collisions.
Lastly, the valence electrons have multiple states. It need not emit a photon to be ready to absorb another.
All of the conjecture is based on math models. We do not know the location of an electron in a molecule and so far the only experimentation is inconclusive, not proof.
True, but completely irrelevant.
Then why the hell did you bring ‘photons’ into the conversation?
Photons or whatever name you believe to be most appropriate, are how energy is being passed around.
EM fields and molecular motion (aka kinetic energy) are how energy is being passed around. Those are distinct forms or energy.
Nonsense. A photon can have any energy at all.
Nonsense.
A photon is a definition.
A photon in a quantum of energy.
A photon has no physical properties.
A photon does not have energy. For the simpleminded, a photon is energy.
The quantum to raise a valence electron to a higher state is dependent on the absorption frequency.
It is different for different atoms and molecules.
Only 15 micron photons, but H2O, about 15 to 50 times more abundant, also absorbs 15 micron photons and many more photons of different energy, which makes H2O, molecule for molecule, at least 3 times more active, plus there are so many more molecules of H2O, especially near the surface where it matters most.
True. However, the claim is that CO2 (and water as well) play no role at all.
There is a narrow band of CO2 absorption that is not overlapped by H2O.
CO2 does nothing, day or night, except grow green flora.
That should clear it up for most people with an open mind.
Above you make the point that CO2 is 1/3rd as active as H2O. Here you say it has no effect.
Care to clear up the discrepancy?
Near the surface, CO2 does NEXT to nothing, compared to far more abundant H2O, plus H20 absorbs photons with many wavelengths.
Above the clouds, H2O plays a very small role due to freezing temps. Almost all H2O is frozen onto other particles.
CO2 is not affected by freezing, but there are few 15 micron photons at higher elevations.
CO2 is not an active absorber at higher elevations, because there are very few photons with the right wavelengths.
To Roy Spencer, for your files
GLOBAL WARMING IN VERMONT
https://www.windtaskforce.org/profiles/blogs/global-warming-in-vermont
Written March 29, 2023
The beautiful graphs are by Willis Eschenbach
Each year has peak temperatures during the summer months June, July, August. The below graph shows those peak temperatures in Vermont, for about 40 years.
Those temperatures were measured by the weather stations in Vermont of the National Oceanic and Atmospheric Administration, NOAA
Vermont has four weather stations; Burlington, St Johnsbury, Castleton and Windsor.
New Hampshire also has four stations
The peak temperatures increased by 1.5 F over 40 years, or 0.0375 F per year.
Almost all people cannot sense the difference of 77 F and 78.5 F
https://storage.ning.com/topology/rest/1.0/file/get/11005165656?profile=RESIZE_710x
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A similar graph shows the minimum temperatures during the months of December, January, February
The minimum temperatures increased by 4.2 F over 40 years, or 0.1 F per year. Most older Vermonters agree, winters in Vermont have been getting warmer.
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Heating demand is driven by temperature difference, which was about (65 F, indoor – 9.8 F, outdoor = 55.2 F) in 1980, and became (65 F, indoor – 14 F outdoor) = 51 F in 2020
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At present, it takes 7.6% less Btu for space heating a house than 40 years ago.
https://storage.ning.com/topology/rest/1.0/file/get/11005165852?profile=RESIZE_710x
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Already-struggling, over-taxed, over-regulated Vermonters, in a low/near-zero, real-growth Vermont economy, would be required to spend at least $1.5 billion per year (during high inflation and high interest times), starting in January 2023, for the next 27 years, to maybe reduce Vermont CO2 emissions to the 2050 target of the VT Comprehensive Energy Plan.
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That extreme hardship spending would have ZERO impact on temperatures in Vermont, which is a near-invisible pinprick on a world map.
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Vermont’s best approach is to be as energy efficient as economically feasible regarding:
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1) Highly sealed/insulated housing
2) High-mileage gasoline vehicles
3) Closing down the less-than-25%-efficient, tree-burning power plants (the energy equivalent of 3 out 4 trees is wasted), such as McNeil and Ryegate.
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Tree-burning power plants and heating plants/stoves are major contributors to Vermont’s CO2 and ground level air pollution from sub-micron particles, which are as toxic as those of coal burning, and most harmful to people, especially pregnant women, children, elderly, and those with cardio/vascular ailments.
The Sea-Tac Airport temp – located on a tree-less grass area within 100 feet of a run way – is the official measurement for Seattle.
One of our local TV stations also posts its own Seattle-based measurement.
The temp at the downtown Seattle station is consistently 1 degree F to 3 degrees F cooler than the airport.
I knew this effect living in Dallas in the mid-80’s. It would be 95 during the day and then stay above 90 until well after dinner time. That surprised me coming from a small town in Kansas where once the sun went down it didn’t take long to cool down to a comfortable temperature.
I’m having problems understanding this. Does UHI only happen at night, then goes away during the daytime?
There are photos of hot times in cities (ex: kids playing in water from fire hydrants) from many years ago. To me, this suggest heat build-up in cities has been a long time thing. So not new and not any more heating than historically. At night, perhaps staying warm is from all the modern heat-generating activities, bigger buildings, more people.
Using ASOS systems at airports changes the discussion. Look at a photo of SeaTac Airport in 1957.
Use Google Earth imagery (latest is 6/28/2024) for the “now” look.
The weather ASOS is here: 47.444691, -122.314428
The NWS claims an elevation of 427 feet. Two miles west the elevation is sea level, 0 feet. If the runway area loses energy at night, there is a large urban heat generator to replace it. Zoom out to 12 miles to see the urban infrastructure. Neighborhoods of Southcenter and Orillia are named.
Wow, the difference is stark to say the least !
Massive airport building expansion.
4 runways vs 1, huge increase in taxi-ways
Massive increase in concrete area.
Massive increase in number of planes, and modern are mostly big jet commercial ones.
Also a rail line and the road system, not to mention the surrounding urban expansion.
It would be incredible if there wasn’t a very significant amount of local warming.
UHI differences become more apparent at night when wind and convective proceeses are at a minimum. When the air is well mixed horizontally and vertically the differences between rural and urban decreases.
It’s a big city. I would think there is a hanger-on into the next day.
UHI has to do with the mass properties of roads and buildings, etc., along with the lack of trees and other plant shadings.
The energy is stored in the concrete (see heat capacity) and slowly releases when the atmosphere cools due to convection, advection, conduction, wind, etc. The whole principle is derived from latency. EM travels at the speed of light. Thermal travels at much less that the speed of sound.
Well OK, I know these simple aspects of UHI. However, the UHI doesn’t reset completely on a daily basis, where it is only obvious at night. There is something funny going on here. If there are scientific reasons for this, I would like Roy to attempt to explain them.
The surface is a heat sink. It doesn’t fall to 0K every night so it can warm again. Diffusion controls the gradient into land and ocean.
Look up frost depths for building foundations in different areas and you’ll get an idea how much heat is stored in soil and water. There are lots of AG sites and land grant colleges that track soil temps.
This seems contradictory. Firstly Dr. Spencer states that in regards the urban heat
island effect that:
“… we also found that relationship largely disappeared by the 1970s, with little warming since then being accounted for by increases in population density.”
but then apparently all the warming in Washington over the last 40 years is the to the UHI.
So which is it?
And the claim that “climate models tell us that days and nights should be warming at much closer to the same rate” seems to be the exact opposite of what most scientists think. See
https://blog.ucs.org/kristy-dahl/with-climate-change-nights-are-warming-faster-than-days-why/
and points out the obvious that increased cloud cover at night causes night time temperatures to rise significantly faster than daytime temperatures.
Somewhat misleading? Nighttime temperatures fall. The minimum temperature is generally found in the absence of sunlight.
If minimum temperatures are rising, it implies a source of heat other than the Sun.
As temperatures actually fall at night, and if CO2 concentration is the same both day and night, then CO2 obviously has no heating effect.
Michael,
It would appear that you have completely misunderstood the original post. The fact that the minimum temperatures are rising just means that at night the temperature does not fall as fast as it did previously. It does not mean that there is a source of heat other than the sun. And again the explanation for that is cloud cover. Most people are aware that during cloudy nights the temperature remains higher than nights when there are no clouds. So rising minimum temperatures at night means that on average there is more cloud cover at night time.
You just did it again. The clouds ARE NOT on fire creating new energy. The energy they receive is from the surface.
You simply can’t justify clouds being warmer than the surface without showing some data that supports your assertion.
Not to me, it doesn’t.
Is this your opinion, or do you have some experimental support? Are you implying that increased CO2 results in increased cloud cover, or something equally bizarre?
Sorry, it would appear I’m right and you’re wrong,
The relationship between night time clouds and relative humidity needs to be taken into account.
Heat is retained by the urban mass during warm day times. That makes night time temps warmer than they would without that urban mass.
The urban mass of DC certainly has grown a lot these past 40 years.
In Greece, etc., many buildings and roofs are painted white to reduce heat retention, already for several thousand years.
Only to you…
If you build a large concrete city and displace all people from it, you still have a large concrete city.
Historically, population growth is associated with enlarging the concrete slab. Once the slab is in place it stays regardless of shifts in population.
Not to mention…tall warm-exterior buildings reduce the celestial spherical view of -273 C outer space…as “seen” from each sq.M of ground surface in the “atmospheric window” wavelengths of 8-14 microns, which are the IR wavelengths with max temps by Wein’s law of -65 C to 90 C…in other words all Earthly temperatures…..and represents about 30-40% of the total radiative heat emitted by surfaces in that -65 to 90 C temperature range.
The increase in surface area is real. The EM radiated by the building exteriors does not go straight up.
This person is no scientist. All I see is regurgitating typical green platitudes about GHG’s.
#1. Your body DOES NOT store heat to be released at night when temperatures cool. Your body attempts to maintain homeostasis all day long through a variety of processes. Your body sweats if it becomes too warm. Your body generates energy by increasing metabolism if the temperature is too cool. Tmax with a small increase is not a problem. Rising Tmin means less energy is used by your body to stay warm. It is a good thing.
#2. Clouds are not on fire. They do not create energy. The earth, land and oceans, are heat sinks. Some of the sun’s insolation is diffused below the surface for later release, be it at night, days later or even weeks later before the heat is released. Unless you can show that clouds are warmer than the surface, the net heat flow is from the surface to the clouds. Clouds can slow the cooling of the surface but cannot change the sign of the gradient.
#3. The paper addresses nothing about temperature change and the concurrent benefits at higher latitudes. The paper just assumes there are no benefits at all.
Jim
you say that “. Clouds can slow the cooling of the surface but cannot change the sign of the gradient.” which is exactly what the article was saying. If you slow down
the rate of cooling in the night time then the minimum temperature will increase since there will be less cooling.
Izaak, you’re playing semantics.
You may not be aware that clouds reduce maximum temperatures as well. The rate of heating during the day is reduced, resulting in reduced maxima.
The fact is that the Earth no longer has a molten surface. It has cooled to its present temperature – unless you can produce something to support any disagreement.
Adding CO2 to air does not make it hotter. In the absence of experimental support to the contrary, anybody who believes so is ignorant and gullible.
Some clouds reduce maximum temperatures. High thin clouds don’t.
Anything that reduces the amount of sunlight reaching a thermometer results in cooling. There are even some ignorant and gullible “climate scientists” who believe that clouds at -40 C make a 30 C surface hotter!
Yes, clouds decrease the diurnal temperature difference. (at both ends)
Clouds are nothing to do with CO2.
Nor can anyone show they are Anthropogenic.
You have just destroyed the AGW meme… again.
Wrong answer. How do I know? Your assertion would result in a higher starting temperature for the following day which means a higher Tmax for the next day. Show your proof that clouds at night cause a warmer following day.
Gradients in time are the correct way to analyze radiation phenomena. Using averages will mislead and will result in wrong conclusions.
From Planck.
If clouds slow the rate of heat loss, then the temperature will be warmer than it otherwise would of been. Clouds don’t need to create any heat for this to happen.
Apart from a slight step around the 2016 El Nino event, there has been essentially ZERO TREND in USA temperature in 45 years.
What other factors, except UHI effect, could be relevant for the difference between daytime and nighttime temperatures and what would be their importance? One can think of clouds, wind direction, sea surface temperature.
Well, sunlight of course. The UHI effect should only be noticed when the anthropogenic heat is significant compared to the Sun’s input. The other factors which you have mentioned would need some mechanism to explain an increase in nighttime minima.
in the case of clouds, you would need to show why increased population results in more clouds only at night. Wind direction and sea surface seem to be rather unrelated to population, but I am easily convinced otherwise, if you have some factual basis for your speculation .
Do you have any?
FWIW, weather presenters on BBC Scotland often give a night time temperature and then say “but in the countryside that will be several degrees cooler”.
Ah, but that’s just an invitation to having a dram.
We don’t need invitations, we just look after our local industries.
Thank you. Dr. Spencer.
Your article/essay makes the point that using Tavg absolute or anomalies by climate scientists hides valuable information that is needed to make a valid assessment of what is occuring in the atmosphere.
This is nothing new to those of us that have concentrated on using Tmax and Tmin as separate temperature trends that must be analyzed.
The increase of Tmin whereas Tmax is fairly constant and winter temps warming is a world wide phenomena.
I can’t bear American gramma. ‘Gotten’
Two people separated by a common language. 🙂
My American gramma has always gotten me a sandwich when it was lunchtime. Sorry about your luck.
The greatest flaw in Tave is (Tmax-Tmin)/2.
The earth is a rotating oblate spheroid.
The warming and cooling of the surface and subsurface structure is not sinusoidal.
The solar irradiance (W/m^2) changes dramatically during the course of the day, primarily due to the angle of incidence and the 2 dimensional projection of the 3 dimensional surface.
People don’t seem to understand how EM waves work and end up with faulty assumptions.The sun’s insolation is a plane wave by the time it reaches the earth. As the earth intercepts the plane wave, every m², mm², μm² receives the same amount of insolation. The angle of incidence determines how much is available for absorption.
People who divide by 4 to get an average insolation have no clue about 3d geometry.
Not to mention that the further you get from the nearest point, the the longer the path through the atmosphere… and the T⁴ effect of the absorbed radiation.
Atmospheric radiation is not a simple arithmetic average, that”s for sure.
Correct.
I’ve done TM link margins, ER IR sensors, and radar.
Fun math.
Thank you.
One point of interest to me would be whether warmer low temperatures, and the narrower range between high and low) has any impact on plant growth and productivity. One possible positive would be a reduction in losses due spring frost damage to fruits and vegetables. I am sure others have better insight than me.
https://www.nature.com/articles/s41598-018-25212-2