Guest Post by Willis Eschenbach
Once again the Week In Review-Science Edition over at Dr. Judith Curry’s website brings up interesting news. It appears that the first of July was hot in the UK, and among others the airport at Heathrow set a record high temperature for the date.. This led to a bit of a flap over in the land of the Anglo-Saxophones.
The British newspaper The Telegraph said that they thought the record was bogus. They theorized that it was caused by jet exhaust and wind changes, which seems quite reasonable to me. In response, the Met Office swung into action and posted up a page on their “Carbon Sense” blog saying that no, it was a break in the clouds that did it, the extra sun raised the temperature. Here’s their money graph:
Figure 1. Graph of solar radiation and temperature at Heathrow for the hottest hour on July 1, 2015
They used this graph to claim that it’s the sun, stupid … but the first problem is, according to their graph, about twenty minutes after the peak in temperature, the clouds parted a bit and the solar input jumped up again to nearly as high as it had gone before … but the temperature didn’t change in the slightest. Well, that’s not entirely true. The second time the sun strength increased, the temperature went down. If the temperature spike early in the record were from the sun, does it make sense to you that a subsequent solar spike twenty minutes later would lead to no warming at all?
The second problem is that the sun strength stayed high, but the temperature started dropping before the succeeding decrease in sun strength.
In any case, they kindly provided the data used in the graph, kudos to them for that, plus the wind direction and strength data so we could see that it’s the sun, stupid … except for one detail. They are using that graph and data to claim that it is the sun, not the wind direction as claimed by the Telegraph, that caused the temperature spike.
With the data we can see that the third problem with their claim is that, for at least this short period, the correlation of temperature with wind direction (0.63) was 50% stronger than the correlation of temperature with sunshine (0.42). So their own data, specially provided to back up their claims, actually disagrees with their claims.
Of course, this means nothing about the longer term. However, for the short-term period around the temperature spike, they certainly have not established their case, so we’re still left with the question of what caused the temperature peak.
Some insight into this question comes from the UK Met Office. They’ve kindly provided these examples of the highest record-setting temperatures in the UK on the first of July, 2015 (see the 7 July 2015 entry here )
Figure 2. Highest temperature records set on the first of July, 2015
Now, looking at Figure 2 we have two possibilities. Either a) human actions are increasing the surface air temperatures recorded at Heathrow, or b) by an astounding historical coincidence, the UK’s largest airport was built precisely on top of the warmest spot on the island … I’m going with a) myself, although YMMV.
So being an inquisitive type of fellow, I decided to take a back-of-the-envelope look at just how much actual thermal energy is released at Heathrow. This doesn’t include the heating effect of all those square metres of runway asphalt, but it’s a start.
A bit of research shows the CO2 released at Heathrow by the actual burning of fuel on the ground and in takeoff and landing (under 3,000 feet [900 m] elevation) is about 1.6 million tonnes of CO2/year. Most of this is in the form of jet fuel, which sounds all high-techy but which is actually kerosene.
Using the conversion factor for kerosene of 71.5 kg of CO2 per gigajoule of energy, this converts to 2.24E+16 joules/year, or 6.13E+13 joules per day, of heat solely from the burning of the fuel.
Now, how much would this release of energy warm the air? Well … how much air are we considering? Heathrow covers a large area, 1227 hectares. So let’s figure the air above Heathrow up to the 3,000 feet elevation under which they’re counting the CO2 emitted.. That’s about 1.12E+10 cubic metres of air, or about 1.43E+10 kg of air.
The specific heat of air is easy, it’s about 1 kilojoule per kilogram per degree C. And we can probably figure that about 30% of the energy is used to produce mechanical work, with the rest lost as heat.
So, imagine that we could put a transparent air-tight dome over Heathrow 3,000 feet (900 m) tall, and one day we burned 6.13E+13 joules worth of kerosene inside the dome, and 70% of that energy went into heat … how much would that raise the air temperature?
Short answer? It would give about a 3°C temperature rise, which is 5.4°F.
Now, of course as soon as the air is warmed by jet exhaust it starts rising, and the heat moves constantly upwards and outwards and cool air mixes in at the bottom, so there is no average 3°C temperature rise on the surface.
But obviously, looking at Figure 2, including warming from all sources there is something like a degree or so of peak temperature increase from the urban heat island at Heathrow.
What is this from? While some is from the acres of hot asphalt runways cooking in the sun, in part it’s from the actual burning of the fuel. Have you ever been caught by the blast from a jumbo jet, even from far away? I have, many times. It smells like kerosene, and it’s warmer than the surrounding air, sometimes much warmer. When one of these blasts hits you, you can easily feel the difference in temperature … and so can the airport thermometer.
With that in mind we can see how desperate the UK Met Office is in their defense of the record. Consider this quote from Dr Mark McCarthy, head of the Met Office’s National Climate Information Centre:
Nor does it make sense to think that a passing breeze could have carried a waft of heat from a nearby aircraft, as Homewood suggests. McCarthy tells Carbon Brief:
“We have checked with [air traffic control] and confirmed that the north runway, which is closest in proximity to our observing station, was being used for landing aircraft. Therefore, landing aircraft would most likely have had idle engines by the time they reached the eastern half of the runway, where our observation station is sited.”
Had passing aircraft generated turbulence, that would help mix the air close to the ground. This would be more likely to lower the air temperature than raise it, McCarthy says.
I fear Dr. McCarthy has not spent enough time out on the tarmac … first, after landing jets do not have “idle engines”. They use their engines to move around the airport, blowing hot air out behind them as they go. And every time they stop, it takes a big blast of hot air to get them moving again. And second, while it is possible for jets to reduce the ground temperature because of the turbulence from their wings, in general, guess what?
Burning about a million gallons (3.4 million litres) of kerosene per day in one location generally does NOT lower the air temperature as McCarthy implies.
Here’s part of the problem. This shows the location of the meteorological station at Heathrow.
Figure 3. Location of the meteorological station at Heathrow Airport is shown by the white circle. The large runway across the middle is the “north runway” referred to by Dr. McCarthy in the quote above. Note the jet at the bottom for scale.
As you can see, the met station is about 150 metres (500 feet) from the north runway. The difficulty comes after landing and slowing down, when the jets turn off of the eastern end of the runway by the met station on one of the side taxiways. At times in that process, their jet exhaust will be pointed directly at the temperature measuring station. Indeed, when jets turn off on either of the two right-hand taxiways in the picture above, their jet exhaust is pointed directly at the met station for the entire trip down the taxiway … and did I mention that the wind was from the south and southeast during the time of the temperature record, blowing from the taxiways towards the met station?
So … did jet exhaust cause the large spike in Heathrow temperatures on 1 July 2015 that created the new record? I’d say:
a) we don’t know, although it certainly seems plausible and winds were in the right direction, and
b) it certainly can’t be ruled out by what the Met Office has shown, but in any case
c) it doesn’t really matter because jet fuel and runway tarmac assuredly warms Heathrow in general, so any Heathrow records are not very reliable or meaningful.
One final thought for you. Heathrow proudly proclaims that from 2012 to 2013 it decreased its CO2 emissions by 11,923 tonnes of CO2. Cue the applause.
However, during the same period, China increased its emission rate by 358,304,399 tonnes/year of CO2. This means that the increase in Chinese CO2 emissions, not the amount of the emissions themselves but the amount of the increase in emissions, is about 40,874 tonnes per hour… which means that all of Heathrow’s proud one-year accomplishment of emission decreases during all of 2012 was wiped out by China in the first 17 minutes after midnight on January 1, 2012.
Dust in the wind …
Regards to all,
w.
As You May Know: If you disagree with someone, please quote the exact words you disagree with so we can all understand the nature of your objection.
Heathrow Airport Details: Over at the Talkshop, tchannon has a good description of the physical layout of the airport here.
Update from the Comments: First, a number of folks mentioned thrust reversers, which I’d forgotten to consider, and the fact that they blow the warm jet exhaust to the sides … in other words towards the met office.
Also, someone talked of the importance of winds. This is very true.
Wind is indeed important, at times crucial. And even if the speed is constant, the direction can be critical. I was going to include the following but the post was getting long. Another example of met office guys not getting out enough.
Now, any swabbie sailor like myself would look at that and say “Yep, that wind is swinging quite a bit”. It looks pretty typical for a wind regime, the wind direction tends to sway from one side to the other once or twice in an hour or so, which this does.
How much is it swinging? Well, it swings from a minimum of 130° (about southeast) to a maximum of 180° (south) during the hour. This is a not insignificant range of no less than fifty degrees.
And the largest rate of swing was a change of fifteen degrees in five minutes … so I’d have to disagree with Dr. McCarthy when he says:
“We’ve looked at wind data and there is no sudden change in wind direction at Heathrow around the time of the record.”
All the best to you all,
w.
This is an example of a sauna ‘kiuas’ in the arctic circle.
http://www.kiuas.fi/media/5147/loimu_ikikiuas_puukiuas.jpg
No one is using IR-lamp and CO2 for the job.
The UKMET Office might be quite good at predicting weather for the next few days.
It has proven it is fairly bad at predicting the future climate.
And I suspect it knows sweet FU about micro climate effects which was the most likely cause of the sharp peak in temperatures at Heathrow Airport.
First up; I have been an Australian glider pilot since 1963 but have given the sport away since I have turned 77 years old.
I have flown power aircraft since late 1959
I am also a now retired grain farmer who farmed since I left school in 1954 and have lived and worked in the open and the weather all my life whilst closely watching and thinking about the incredible variety of weather phenomena I have seen, a lifetime study which was due to my interest and personal commitment to my sport of gliding or more accurately, Soaring
The Met Offices supposed record temperatures DOES NOT need any jet exhaust or any other explanation
to achieve that spurious high point in that recorded temperature high point.
When you get past the mid 30C temperature range Glider pilots will often find a patch of trees or a complex of buildings or even the wind lee side of a small and steep hill to find where the still air wind shadow effect allows a very considerable warming of the localised ground level patch of air from the suns heat allied with the ground’s heat sink effect and the release of that heat to warm the air mass directly above it.
In Heathrows situation, an even bigger, higher temperature heat sink in the seal and concrete in front of and in the wind shadow of the terminal buildings when a SE wind is blowing.
This more often than not under the right circumstances such as the wind shadows I described above, the wind shadow effect results in a “thermal” being generated, [ a rising column of warmer, therefore expanded, therefore a lighter air mass than the surrounding air mass and therefore like a hot air balloon, same principle, the warmer lighter air mass rises and forms a thermal column entrapping and drawing air into it at the bottom and creating a “thermal” , a rapidly rising column of warmer lighter air used by glider pilots to cover hundreds of kilometres distance on a good day.] which then detaches itself as the parcel of warmer, lighter air begins to ascend and the newly created “thermal” then drifts downwind.
Standing out on a sealed 30 metre wide Australian country runway which is one hell of a lot smaller than any sealed surface or concreted runways and hard surface standings at Heathrow, we often see thermals begin on that much higher than air temperature, heat sink sealed runway and then drift off down wind.
When a thermal gust goes through it might take a half a minute or even a few minutes in open vistas , being slower to pass in heavily built up areas as the wind speed at ground levels is greatly reduced in velocity, for such a thermal gust depending on its size, intensity, the wind strength and etc for it to pass through and it is noticeable that the air within that thermal cell and the associated wind gust is degree or more warmer than before and after the thermal has passed through.
The Heathrow five minute wind direction [above] also indicates that there was a minor shift in the wind direction consistent with the start of the rotation of a large warm air pool at ground level, the start of a thermal, towards a more southerly bearing [ banded at 14.13 in the above wind rose graph ] before the wind swung back past the average bearing further into the SE and then settled back over a few minutes to the before and after bearing.
A very typical effect from the passing of a large “developing thermal” air mass.
Further anybody riding in the back of a “ute” [ “utility” ; “pickup” to Americans ; riding in the back of a ute supposedly no longer allowed by our nanny state here in Australia,] at say 50 or more KPH on a warm to hot day, one will experience quite large patches of quite noticeably warmer air as in a couple or more degrees warmer for a some tens or even hundreds of metres followed by a sharp change in a few metres back to cooler air as the warmer patch of air is left behind and another patch of cooler air lasting some hundreds distance of metres is entered in turn.
The Heathrow spike in temperature is entirely consistent with a normal and regularly experienced “thermal” created spikes of a degree or more passing slowly through the station after the “thermal” has come into existence in the SE wind shadow of the terminal buildings and then has broken away from the effects of the terminal buildings wind shadow and the very large heat sink effects of the sealed and concreted hard standings.
It has consequently then drifted in this case, directly downwind from the terminal buildings wind shadow effect and across the station giving the station a sharp increase and then fall in temperature in line with the usual low level near ground level gliding described “thermal” temperature characteristics and in line with the temperature graph depicted in our headline post..
Excellent points, thanks!. Aviators, especially those who depend on rising columns of air for lift, are the real experts on the atmosphere and its behavior. You could teach our climate scientists a thing or two! The air isn’t that well mixed–inferring behavior from one location at one time (a peak temp) ignores essentially everything! Using a boiled-down average of daily highs and lows over a month of observations to describe our complex, chaotic atmosphere is next to useless.
Land subsets of global temperature datasets involve 3,652-3,623 daily highs and daily lows per decade, at each of thousands of stations. Places that get thermals tend to get several of them each day they occur. I don’t see any chance for any significant change in a recorded trend if one thermal hits a weather station instead of missing it, or vice versa. The main concern with surface stations is if during the period of record the surface around a station changes, the station changes, or the station is moved.
Sorry to be unclear. I’m confident that average highs and average lows can be collected and calculated and that influences such as jet wash or thermals are likely infrequent enough not to make a huge difference over many observations. I’m questioning the notion that averaging highs and lows relates well to an average daily temperature. Averaging the daily high with the daily low provides a number that does very little to describe the heat content of a day. The 15 minute spike at Heathrow that is under discussion here is a nice example–it skews the daily average high but with a very short interval of additional heat. I would prefer to see an integrated average of more frequent values taken over 24 hours since that would better reflect the heat content of the atmosphere for the day. Very rich data are being ignored in pursuit of a mostly meaningless average daily, monthly or yearly temperature.
Yes, I was thinking “thermals” too. Checked the British Gliding Associaton website (see “BGA ladder” -competative list of glider flights for each day) and it was a good soaring day, with 23 pages of results and seven flights over 600km. So it was quite thermic that day. And I think a thermal can easily suck warm jet exhaust a hundred meters of so as it pulls in air to feed the rising air thermal bubble.
I do wonder whether these Met Office folks are concious of how they always seem to be defending a warmist world view (to paraphrase “no, no, no, couldn’t possibly be jet blast, must be global warming”) instead of actually doing science.
PS: I haven’t checked them all, but I recognise a number of the stations listed in the records table as being airfields too.
Wouldn’t the turbulence from heavy aircraft taking off and landing at this particular site and time disrupt thermal formation ?
I’ve seen no comment regarding aircraft direction and that could have a marginal effect. With the runways aligned 09 / 27 and the prevailing winds SW to SSW / WSW most take-offs / landings are towards the west. (My experience is that about 90% are westward.) With a southerly / south-easterly wind on July 1st, they would have been west to east.
Another factor (from personal experience) is the time taken to get through the “traffic jam” before take-off. There is a secondary peak period around mid-day and having tried taking flights around then, to avoid peak times, I can say that it ain’t necessarily so.
Aircraft using runway 09L during the time of the reported hottest temperature were as follows:
1413 BA272 from San Diego Boeing 777-200
1415 BA274 from Las Vegas Boeing 747-400
1416 BA775 from Stockholm Airbus A320
1417 BA842 from Dusseldorf Airbus A319
1418 BA905 from Frankfurt Airbus A319
1419 BA1445 from Edinburgh Airbus A320
From a visual aspect I don’t see a strong correlation between the radiation (sunshine) and temperature plot.
What I do see from the aircraft movements, were two large planes a 777 (two engine) and a 747 (four engine) landing with max reverse thrust close to the thermometers, ably assisted by a S/SE wind blowing the heat vortices in the thermometers direction.
Sorry for the nitpicking but I can’t stand it anymore: it’s just “Airbus 320”, not “Airbus A320”.
It would help if I thought a bit more about the configuration of max thrust, of course landing on 09L it would have been further west on the runway. However on further analysis if the 747 had slowed on roll out and exited on taxiway A5 or A6 it would have needed a thrust boost to get rolling for exist. A5/A6 would have pointed its engines directly to the position of the thermometers, 120m away, still assisted by the S/SE wind blowing the heat vortices.
It would be nice if all traffic at Heathrow could be stopped for a while in order to see what difference it would make to temperature. Maybe Greenpeace could arrange it 😉
It looks like they tried…
http://www.bbc.com/news/uk-england-london-33503167
“We would have to compare the speed of a plane at 3000 feet during take-off and landing”
Flightradar24.com will give you that information – just track an aircraft from departure, and you’ll get frequent updates of altitude and speed. Naturally, there will be quite a variation, depending on the size of aircraft, and its weight for a particular flight.
“It would interesting to have a second weather station at Heathrow, well away from tarmac and well away from the one referred to in Willis’s article”
Paul Homewood (who runs the “Not A Lot Of People Know That” blog) lists a number of nearby privately operated weather stations in some of the many posts that inspired Christopher Booker to pen the Telegraph piece:
https://notalotofpeopleknowthat.wordpress.com/?s=Heathrow
Look at the July the 3rd & 5th stories.
Further to my last comment, here are some recent observations: British Airways B747 en-route to JFK passing 2925ft @ur momisugly 180kts, a BA A320 to Helsinki passing 3075ft @ur momisugly 230kts, Singapore Airlines A380 (en route to Singapore) passing 3025ft @ur momisugly 230kts, a United B787 Dreamliner en route to Houston passing 3250ft @ur momisugly 180kts, American Airlines A330 en route to Charlotte passing 3000ft @ur momisugly 163kts
Note that (virtually) all aircraft climb at a considerably greater rate than they descend during approach, when they are following a standard 3 degree glide-slope. Flightradar24 includes the rate of climb/descent information. This would mean the “3000ft Bubble” referred to earlier is much larger if both landing and departing aircraft are included.
Reblogged this on the WeatherAction News Blog and commented:
While some is from the acres of hot asphalt runways cooking in the sun, in part it’s from the actual burning of the fuel. Have you ever been caught by the blast from a jumbo jet, even from far away? I have, many times. It smells like kerosene, and it’s warmer than the surrounding air, sometimes much warmer. When one of these blasts hits you, you can easily feel the difference in temperature … and so can the airport thermometer.
An excellent piece by Willis that really shows the Met Office must try harder. It was a record that day, but not a valid one. The Met Office contortions in defence of the narrative sadly undo every bit of their great historical works, showing instead their unswerving devotion to Climate Lysenkoism.
Some figures about how far the jet plume extends beyond the tail of a 747 during takeoff (taken from official Boeing documentation at: http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_8.pdf)
200 mph (=Class 5 hurricane) 64 ft
150 mph (=Class 4 hurricane) 241 ft
100 mph (=Class 2 hurricane) 531 ft
50 mph (=Strong Gale) 1748 ft
35 mph (=Moderate Gale) 2588 ft
According to the same source during taxying “Moderate Gale” will only extend about 130 feet on an absolutely flat taxiway, but even a 1% slope is enough to increase this to 320 feet with “Strong Gale” to about 100 feet.
Anyone that thinks Heathrow isn’t one of the most pronounced heat-islands in the world and useless (or worse) as a climate indicator needs a lobotomy.
I really love this web site…I have learned so much!
While reading this article, I was guessing that the amount of air traffic during that period was at an unusual peak. I pictured a traffic jam of jets on the tarmac in front of the station, just idling and waiting for their gates to become available.
Clive Best remarks:
That’s strong evidence the temperature spike was jet-induced, but the A380 operator is Etihad Airways, not
Etihan.Clive Best has updated his analysis with better data, correct times:
I asked the UKMO whether the temperature record at Heathrow was reliable, in view of the increase in temperature relative to CET since 1948 and I received the following reply:
Thank you for your email enquiry in connection with the temperatures recorded at Heathrow.
As with all our sites, our weather station at Heathrow conforms to World Meteorological Organisation (WMO) guidelines in relation to site and specific sensor locations to ensure relativity across sites and for historical comparisons. Details of these guidelines may be of interest to you and can be found at http://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.html and ensure that a site is representative of the local area. While it isn’t possible to have an “ideal” or “normal” site this ensures that external factors are limited and to have continuity. All our sites are routinely visited by specialists and engineers to maintain high standards of recording and exposure of instrumentation along with accurate quality checks of observational data.
The links below may be of interest to you and expand in further detail the points mentioned above.
http://www.metoffice.gov.uk/climate/uk/interesting/july2015
Discusses the heat wave and compares with other heat waves in the historical record
http://blog.metoffice.gov.uk/2015/07/07/on-the-record-observing-a-heatwave/
Discusses record at Heathrow and compares with other stations in the area
http://www.climate.gov/news-features/event-tracker/summer-heat-wave-arrives-europe
Heat wave more widely across Europe.
http://www.carbonbrief.org/blog/2015/07/met-office-wind-data-dispels-doubt-about-cause-of-heathrow-high-temperatures/
Therefore based upon the points covered, the increase in temperatures over the records at Heathrow can be considered an accurate and reliable representation of the local area, suitable for comparison against other sites and historical records.
The thing that strikes me the most is that we are going to hourly readings vs twice a day. This guarantees meaningless high and low temperature records when compared to the old record. You only can compare readings at the 2 points in the day that were performed historically.
Willis wrote: “… 6.13E+13 joules per day, of heat solely from the burning of the fuel …
1227 hectares … 3,000 feet elevation. That’s about 1.12E+10 cubic metres of air, or about 1.43E+10 kg of air. So, imagine that we could put a transparent air-tight dome over Heathrow 3,000 feet (900 m) tall, and one day we burned 6.13E+13 joules worth of kerosene inside the dome, and 70% of that energy went into heat … how much would that raise the air temperature? Short answer? It would give about a 3°C temperature rise, which is 5.4°F.”
Of course, planes can’t land with a transparent, air-tight dome over Heathrow. In the absence of such a doom, wind continuously sweeps the air warmed by burning jet fuel away from the airport and replaces it with fresh cooler air. With an area of 1227 hectares or 12 sq km, it should take a wind of only 3 kilometer per hour to sweep fresh air into the airport every hour and convert 3 degC (of warming each day) to a negligible 0.1 degC (of warming each hour). This problem could be fixed by assuming that the burning jet fuel warms only the lowest 300 feet of the air over the airport. Unfortunately, the principles fluid flow over surfaces predict a turbulent boundary layer that transfers heat vertically from the surface.
Similar arguments suggest that the energy consumed in cities (which is probably much larger than a few dozen jet planes consume per hour in a 12 sq km airport) is not the main cause of UHI.
Your arguments about sunshine and wind direction appear sensible, but what actually happened at Heathrow is irrelevant. Temperature records were set in numerous locations the same day elsewhere in England. And those records represent weather, not climate change.
Frank
Which other cities near London set climate records?
Willis lists about 10 stations with records. His link to the Met Office post has a map with many more:
http://www.carbonbrief.org/blog/2015/07/met-office-wind-data-dispels-doubt-about-cause-of-heathrow-high-temperatures/
Thanks, Frank. I don’t recall ever making the claim that jet fuel burning was the cause of UHI. So you’re attacking a straw man. What I did instead was try to get a physical sense of just how much energy is in the jet fuel.
My point was that if there is enough energy wandering around the airport that if it was released into a huge space above the airport it would jack the temperature by 3°C, there’s plenty to mess with temperature sensors. I note that you neglected to quote my disclaimer, viz:
So no, I don’t think that the jet fuel burning is the MAJOR cause of UHI … but a quick calculation shows that the fuel burned at Heathrow is about 1 W/m2, so it is too large to ignore entirely.
Finally, you say:
I don’t understand why “what actually happened at Heathrow is irrelevant”. Yes, temperature records were set elsewhere … and most of them were at AIRPORTS. This is indeed relevant to the climate discussion.
It is also not “irrelevant” because this “record high at Heathrow” meme has appeared all over the web. Hang on … OK, I find about 4,000 news articles discussing the record high, and lots more other analyses.
Finally it is not “irrelevant” because according to the 72-point screaming headlines this was the “HOTTEST JULY DAY ON RECORD!!!”, so it is being hyped by the alarmists. As such, it is extremely relevant to find out whether this record is valid, or whether it’s just hot air (from jets).
Because me, I’m not impressed by a temperature record high based on jet blast …
w.
PS—Your claim that “Similar arguments suggest that the energy consumed in cities (which is probably much larger than a few dozen jet planes consume per hour in a 12 sq km airport) is not the main cause of UHI” might be true … but it would have more force if you actually linked to one, just one, of your claimed “similar arguments” …
No doubt that insolation LEADS the temperature in the rise to the day’s peak. What confuses many brainwashed into a “radiation-only” perspective is the subsequent cooling behavior, which is typically the result of moist convection–the principal mechanism of heat transfer from surface to atmosphere.
1sky1 July 20, 2015 at 11:28 am
Thanks, 1sky1. While you are correct that the “principal mechanism of heat transfer from surface to atmosphere” is what you call “moist convection” (by which I suspect you mean evapotranspiration), it is not the principal way that the surface loses energy. That indeed would be radiation.
w.
Willis:
Moist convection is the inanimate transport of humid air from the near-surface boundary layer into the atmosphere. It has little to do with the transpiration produced by plant life. And if you examine the results of careful energy-transfer experiments world-wide in terms of the Bowen ratio, instead of the cartoon physics of Trenberth et al., you’ll discover the real-world dominance of moist convection.