The Version 6.0 global average lower tropospheric temperature (LT) anomaly for July, 2019 was +0.38 deg. C, down from the June, 2019 value of +0.47 deg. C:
The linear warming trend since January, 1979 remains at +0.13 C/decade.
Various regional LT departures from the 30-year (1981-2010) average for the last 19 months are:
The UAH LT global anomaly image for July, 2019 should be available in the next few days here.
The global and regional monthly anomalies for the various atmospheric layers we monitor should be available in the next few days at the following locations:
A lunar outpost on the rim of Shackleton Crater at the moon’s South Pole as envisioned by artist Jorge Manes Rubio (ESA).
Living on the Moon would be challenging, to say the least. A total of twelve Apollo moon-walkers between 1969 and 1972 spent a cumulative 80 hours walking around on the surface of the moon. Obviously, they had to bring their own food, water, and air to breathe.
NASA engineers did a good job of preparing the Apollo astronauts for what would be a very non-Earth-like experience. But the moon-walkers were there for only one to three days on each of the lunar landing missions, and were focused on getting historic stuff done as quickly as possible before coming home.
Let’s say you were traveling to an existing moon base as a tourist, with enough food, water, and air to spend a month there, and a round-trip ticket to get there and back home. What are some of the differences you would experience living on the Moon compared to Earth?
1) No atmosphere, no weather, no water, no life
One of the most obvious differences with Earth is that the moon has no atmosphere. No atmosphere means no blue sky, no air to breathe, no weather, and no life. Obviously, you could not simply “go outside”; you would have to have a pressurized space suit. And when you did go outside, there would be no trees, lakes, grass… just a barren grey desert with craters, rocks, and rolling hills.
Apollo-16 lunar panorama with astronaut John Young, April 21, 1972.
Walking around near the South Pole (a likely choice for a moon base, see below) would be treacherous because with the sun low on the horizon, and no atmosphere-scattered sunlight to help illuminate the landscape, any low spots would be almost totally black — some might look like bottomless holes. Venturing into larger craters would require artificial lighting.
2) Gravity: If you weigh 200 lbs on Earth, on the Moon you only weigh 33 lbs
As the Apollo astronauts found out, walking around with only 1/6 of Earth gravity takes some getting used to. They developed a “bunny hop” method of moving around that seemed to help keep them from falling over. Astronaut Harrison Schmitt (the last man to walk on the moon) compared it to walking on a giant trampoline. Without much gravity, your muscles would weaken and you would have to have a daily exercise plan to keep from becoming a couch potato.
3) Good luck sleeping, daytime on the moon lasts for 2 weeks
The moon takes 29.5 Earth days to rotate, so that means two weeks of daylight followed by two weeks of darkness for almost everywhere on the moon. To avoid the problem of a moon base being plunged into darkness for 14 days at a time, with temperatures falling to 280 deg. F below zero, a moon base would probably be located near the South Pole, where there are locations that are almost always sunlit, and temperatures remain more moderate. If that is where you spent your month, the sun would hug the horizon, and it would circle around you during your 1-month stay. You would probably still use a 24-hour (Earth time) clock to maintain a healthy circadian rhythm.
4) The day-night temperature range is over 450 deg. F
Because the lunar surface is relatively dark (about the same reflectivity as the open ocean), and because there are no clouds or weather to cool the surface, daytime temperatures soar to 250 deg. F at the lunar equator. The six Apollo missions were planned so that the sun would not be very high in the sky to limit how hot the astronauts and lunar module would get.
During Apollo-11, the sun’s elevation was only 15 deg. early on a lunar morning, so that lunar daytime surface temperatures were reduced. (This also explains why there is no shadow of the flag to the right; note the length of the “thigh gap” between the shadows of Buzz Aldrin’s legs.)
Just as dangerous is the fall of lunar temperatures to -208 deg. F at during the two-week long lunar night. This is probably too large of a temperature range for humans to cope with in terms of heating and cooling of buildings and spacesuits, which is partly why many believe a weakly sunlit site near the South Pole would make the best place for a permanent lunar outpost. Temperatures at the South Pole on solar-illuminated crater ridges hover around 32 deg. F (0 deg. C), and the sun shines for over 90% of the year at some higher elevation locations:
“Lunar Temple” at the moon’s South Pole, by artist Jorge Manes Rubio (ESA).
5) The lunar sky is always black, with almost no daytime stars
With no atmosphere, the sky would always appear black, even when the sun is shining. But because the sun shining on the moon surface produces considerable light, all but the brightest stars would not be visible during the daytime. It’s the same reason you cannot see stars next to the full moon. The Apollo moonwalkers generally did not see stars, and neither do astronauts on the International Space Station when they are on the sunlit side of the Earth. Gene Cernan (Apollo 17) said he could see a few stars if he stood in the shadow of the Lunar Module to reduce the amount of sunlight being reflected from the lunar surface.
At night, though, the stars would be spectacular. I suspect at the South Pole, many more stars would be visible since the landscape would be only weakly illuminated by the sun, and your eyes would adapt to the twilight-like brightness.
6) The view of Earth would be amazing
Since the Earth is 3.7 times larger than the moon, it covers over 15 times as much of the sky as does the moon. This combined with the fact that the Earth is colorful would make the Earth a spectacular sight. A person with reasonably good eyesight would be able to identify the continents. You can get a good idea of the dramatic difference between how the Earth and moon look from this DSCOVR satellite image of the moon transiting the Earth:
The appearance of the Earth rising above the moon’s limb as Apollo-11 orbited the moon was greeted with amazement by the astronauts as they scrambled to change from black & white to color film to capture the sight.
Furthermore, since the Earth rotates over 24 hours, you would get to see different sides of the Earth, rather than just one side of the moon we are limited to here on Earth. There would be phases of illumination throughout the month, just like we see of the moon, but they would be reversed. A “full Earth” would occur during the “new moon” on Earth, while a “new Earth” from the moon would occur during the “full moon” here on Earth. Also, when there is a lunar eclipse on the Earth there would be a solar eclipse on the moon, and when there is a solar eclipse on the Earth, there would be an “Earth eclipse”, with the shadow of the moon falling on a portion of the Earth:
How a solar eclipse on Earth might appear from the moon (Pat Rawlings).
7) The Earth is always in the same part of the lunar sky
Because the same side of the Moon always faces the Earth, the Earth’s position in the lunar sky would always remain the same (or nearly so) as seen from the moon’s surface. There would be no Earthrise or Earthset the way we have moonrise and moonset. If you were near the moon’s South Pole (where sunlit locations stay relatively cool) the Earth would dramatically hang just above the horizon in one spot, while the sun slowly travels around the horizon over the course of one month. This would make the whole Earth viewing experience even more breathtaking.
8) Meteors : Bring your Kevlar vest
The moon is constantly being bombarded by tiny micrometeors. Rarely, one large enough to be seen from Earth hits the moon, such as this one captured by accident by an astrophotographer while photographing the lunar eclipse on January 20, 2019:
Without an atmosphere to slow the meteors down and burn up all but the largest of them, they hit the moon surface at astonishing speeds. For comparison, a bullet fired by a 30 caliber rifle travels close to 2,000 mph as it leaves the muzzle. Now imagine a small meteor travelling at 45,000 to 196,000 mph. A BB-sized meteor travelling at 100,000 mph would hit your space suit with the energy of 90 30 caliber rifle bullets slugs fired at point-blank range. All of that energy would be concentrated like a knife point in the tiny BB-size spot. Luckily, the probability of being hit by a meteor of even that small size is believed to be vanishingly low. But the possibility would always be in the back of your mind. The moon-walkers (like space-walkers) wore suits with protection against very tiny micrometeors; they just had to hope there weren’t any larger ones with their name on it.
9) Smelly, messy moon dust
The Apollo moon-walkers found that the lunar soil tended to cling to everything, and it has an odor somewhat like gunpowder or wet sand. Very fine and abrasive (like tiny shards of glass), it would probably present a long-term health risk in the pressurized buildings of a lunar base, and much effort would go into cleaning it off of space suits and equipment brought in from outside and filtering it from the air.
Lunar dust in a vial given to a woman by first moon-walker Neil Armstrong (photo Christopher M. McHugh).
I’m sure there are other unusual aspects of living on the moon I haven’t thought of. Just the daily routines of life would be difficult, and much effort would be expended on activities necessary to sustain life: food, recycling of water, waste disposal, oxygen generation and removal of excess carbon dioxide, energy generation and storage, etc. Here I’ve assumed all of that has already been taken care of for your month of leisurely lunar living.
While it is possible that the human component of recent warming might have made the heat wave slightly worse, there are three facts the media routinely ignore when reporting on such “record hot” events. If these facts were to be mentioned, few people with the ability to think for themselves would conclude that our greenhouse gas emissions had much of an impact.
1. Record High Temperatures Occur Even Without Global Warming
The time period covered by reliable thermometer records is relatively short, even in Europe. Due to the chaotic nature of weather, record high and record low temperatures can be expected to occur from time to time, even with no long-term warming trend.
The question is, are the number of record high temperatures increasing over time? At least in the U.S., the answer is ‘no’, as the number of days over 100 and 105 deg. F have not increased (see Fig. 5 here). One would need to study the data for Europe to see if the number of record highs is increasing over time.
Then, even if they are increasing, one needs to determine the cause. Most of the warming since the Little Ice Age (up to about 1900) occurred before greenhouse gases could be blamed. We have no temperature measurements during the Medieval Warm Period of 1,000 years ago. How hot were some of the summer days back then? No one knows. Weather changes, which leads me to my next point.
2. Summer Heat Waves are Weather-Related, and Unusual Cold is Usually Nearby
The recent excessive heat in Europe wasn’t caused by summer air sitting there and cooking in a bath of increased human-emitted carbon dioxide. It was caused by a Saharan Air Layer (SAL) flowing in from that gigantic desert to the south.
This happens from time to time. Here’s what the temperature departures from normal looked like at ~ 5,000 ft. altitude:
Fig. 1. GFS model depiction of the 850 hPa level (about 5,000 ft. altitude) temperature departures from normal at midday 29 June 2019, showing a hot Saharan air mass that had flowed north over western Europe, as a cold arctic air mass flowed south over eastern Europe. (Graphic courtesy of WeatherBell.com)
The SAL event flowed north from the Sahara Desert to cover western Europe while a cold air mass flowed south over eastern Europe. As evidence of just how large natural weather variations can be, the full range of temperature departures from normal just over this small section of the world spanned 25 deg. C (45 deg. F).
Meanwhile, the global average temperature anomaly for June (from NOAA’s Climate Forecast System, CFSv2 model) at the surface was only +0.3 deg. C (0.5 deg. F), and even for one day (July 1, 2019, from WeatherBell.com) remains at +0.3 deg. C.
Do you see the disparity between those two numbers?: weather-related temperature variations of 45 deg. F versus a climate-related global average “warmth” of only 0.5 deg. F.
Here’s what the situation looked like at the surface:
Fig. 2. As in Fig. 1, but for surface air temperature.
The range in surface air temperature departures from normal was was 32 deg. C (about 58 deg. F), again swamping (by a factor of 100) the global “climate” warmth of only 0.5 deg. F.
Thus, when we talk of new temperature records, we should be looking at normal weather variations first.
3. Most Thermometer Measurements Have Been Spuriously Warmed by the Urban Heat Island Effect
I am thoroughly convinced that the global thermometer record has exaggerated warming trends due to the Urban Heat Island (UHI) effect. When natural vegetation is replaced with buildings, pavement, and we add spurious heat sources like air conditioning units, cars, and ice cream trucks, the microclimate around thermometer sites changes.
Many of us experience this on a daily basis as we commute from more rural surroundings to our jobs in more urban settings.
For example, Miami International Airport recently set a new high temperature record of 98 deg. F for the month of May. The thermometer in question is at the west end of the south runway at the airport, at the center of the Miami-Ft. Lauderdale metroplex. Only 120 years ago, virtually no one lived in Miami; in 1896 it had a population of 300.
The UHI effect is so strong and pervasive that it is now included in the GFS weather forecast model, and in the case of Miami’s recent hot spell, we see the metroplex at midnight was nearly 10 deg. F warmer than the rural surroundings:
Fig. 3. GFS surface temperature analysis for around midnight, 28 May 2019.
When a thermometer site has that kind of spurious warming at night, it’s going to produce spuriously warm temperatures during the day (and vice versa).
The most thorough analysis of the UHI effect on U.S. temperature was by Anthony Watts and co-authors, who analyzed the siting of hundreds of thermometers around the U.S. and showed that if only the best (most rural) sited thermometers are used, U.S. warming trends are roughly cut in half. Curiously, they found that the official NOAA-adjusted temperature data (which uses both urban and rural data) has even more warming than if no UHI adjustments were made, leading many of us to conclude that the NOAA UHI adjustment procedure has made the rural data look like urban, rather than the other way around as it should be.
How does this impact the recent record high temperatures in France? There is no question that temperatures were unusually hot, I’m only addressing the reasons why high temperature records are set. I’ve already established that (1) record high temperatures will occur without global warming; (2) weather variations are the primary cause (in this case, an intrusion of Saharan air), and now (3) many thermometer sites have experienced spurious warming.
On this third point, this MeteoFrance page lists the temperature records from the event, and one location (Mont Aigoua) caught my eye because it is a high altitude observatory with little development, on a peak that would be well-ventilated. The previous high temperature record there from 1923 was beat by only 0.5 deg. C.
Some of the other records listed on that page are also from the early 20th Century, which naturally begs the question of how it could have been so hot back then with no anthropogenic greenhouse effect and little urban development.
The bottom line is that record high temperatures occur naturally, with or without climate change, and our ability to identify them has been compromised by spurious warming in most thermometer data which has yet to be properly removed.
The Version 6.0 global average lower tropospheric temperature (LT) anomaly for June, 2019 was +0.47 deg. C, up from the May, 2019 value of +0.32 deg. C:
The linear warming trend since January, 1979 remains at +0.13 C/decade.
Various regional LT departures from the 30-year (1981-2010) average for the last 18 months are:
Recent news events regarding heat waves, record high temperatures, and even yesterday’s hailstorm in Guadalajara, Mexico, are commonly presented as evidence of a changing climate system. The trouble is that making such an association is a stretch, at best, for a number of reasons.
Today I’ll deal with the Guadalajara “freak” hailstorm, which is claimed to have “dumped up to 6 feet of ice” on portions of the city.
The Mountains of Northwest Mexico are “Hail Central”
The high elevations of northwestern Mexico are notorious for hailstorms during the “Mexican monsoon” season, when warm moist air flows in from the Pacific and is forced to rise over the mountains. This old hand-drawn map of global hail frequency shows the area clearly, and Guadalajara is in the middle of it.
While most of that part of northwest Mexico is only sparsely populated, rarely a significant hailstorm will happen to hit a city as large as Guadalajara, simply because eventually every place gets hit. This is the same issue as Hurricane Sandy hitting New York City… it was not an exceptional hurricane (Cat 1 at landfall), but it is rare for one to make a direct hit of a major metropolitan area (and at high tide, from the worst possible angle, etc.).
The historical hail problem at the higher elevations of western Mexico is so bad that a Volkswagen assembly plant there once resorted to using unproven ‘hail cannons’ to try to protect its inventory. Ironically, the local farmers then blamed the hail cannon for working too well, and supposedly causing drought conditions. Hail cannons were more popular in the early 20th Century, as evidenced by the 3rd International Congress on Hail Shooting being held in Lyon, France, way back in 1901.
No, “Feet” of Hail Didn’t Fall
I’m sorry, but “6 feet of ice” was not dumped on the city. When a major hailstorm like this hits, especially with a lot of small hail and heavy rain, the flooding deposits the hail into current-driven drifts. Rivers of floodwaters containing the hail caused localized piles of hail to accumulate.
For example, look at this hailstorm aftermath in Denver, CO. See all of the ice in the street, but not in the yard?:
I did not see any hail dents in the video and photos accompanying the news reports; the storm had an abundance of small hail in it.
A Moister Atmosphere from Global Warming Wasn’t to Blame
So, was the intense storm from more moisture in the atmosphere due to global warming?
No, there was actually less water vapor than normal. Here’s the GFS weather forecast model total precipitable water (basically, how much water is available in the lower atmosphere to feed precipitation systems) forecast only 6 hours into that model run, which was about the time of the hail storm. The water vapor available to the storm was actually below average.
GFS 6 hour forecast of total precipitable water at the time of the Guadalajara hailstorm of June 30, 2019 (forecast graphic from TropicalTidbits.com).
I’ve seen a few news reports with quotes about this hailstorm being exceptional and so caused by climate change. There is no evidence that this is the case.
It is a truism that any observed change in nature will be blamed by some experts on global warming (aka “climate change”, “climate crisis”, “climate emergency”).
When the Great Lakes water levels were unusually low from approximately 2000 through 2012 or so, this was pointed to as evidence that global warming was causing the Great Lakes to dry up.
Take for example this 2012 article from National Geographic, which was accompanied by this startling photo:
The accompanying text called this the “lake bottom”, as if Lake Michigan (which averages 279 feet deep) had somehow dried up.
Then in a matter of two years, low lake levels were replaced with high lake levels. The cause (analysis here) was a combination of unusually high precipitation (contrary to global warming theory) and an unusually cold winter that caused the lakes to mostly freeze over, reducing evaporation.
Now, as of this month (June, 2019), ALL of the Great Lakes have reached record high levels.
Time To Change The Story
So, how shall global warming alarmists explain this observational defiance of their predictions?
The trouble is that there is that there is no good evidence in the last 100 years that this is happening. This plot of the four major lake systems (Huron and Michigan are at the same level, connected at the Straits of Mackinac) shows no increased variability since levels have been accurately monitored (data from NOAA Great Lakes Environmental Research Laboratory):
This is just one more example of how unscientific many global warming claims have become. Both weather and climate are nonlinear dynamical systems, capable of producing changes without any ‘forcing’ from increasing CO2 or the Sun. Change is normal.
What is abnormal is blaming every change in nature we don’t like on human activities. That’s what happened in medieval times, when witches were blamed for storms, droughts, etc.
One would hope we progressed beyond that mentality.
Noctilucent (night shining) clouds are being reported farther south than ever before, with reports from southern California, New Mexico, Oklahoma, and southern Ohio.
Noctilucent clouds (NLCs) over Corvallis, Oregon on June 10, 2019 (Tucker Shannon).
These NLCs form in the upper mesosphere at an altitude of about 85 km (around 50 miles), which is above 99.999% of the atmosphere. It is the same altitude where meteors and thunderstorm sprites occur, but somewhat below the altitude of the aurora.
Average temperature profile of the atmosphere (adapted from a presentation by Prof. Nicholas Mitchell, The University of Bath).
They are visible about 1-2 hours after sunset or before sunrise, when other clouds are in darkness but these are still illuminated by the sun due to their high altitude. It is believed that water vapor from oxidation of methane condenses on meteor dust, leading to the ice cloud formation.
The conditions for NLC formation require extremely cold temperatures, as low as -150 deg. F. I’ve been looking for online sources of near real time satellite data which might be used to monitor them, but there isn’t much out there (more on that, below). The AIM instrument on the TIMED satellite provides daily images, but for some reason the clouds the satellite views seem to be only from the latitude of central Canada northward.
NLCs have been increasing in recent decades. They are always more prevalent during solar minimum conditions (which we are now experiencing), when there is less solar energy heating the extreme upper atmosphere. But there is also a long-term trend upward:
(a) SBUV merged seasonal average IWC (ice water content) values for three different latitude bands: 50N-64N (purple triangles), 64N-74N (green crosses) and 74N-82N (blue squares). The solid lines show multiple regression fits to the data for the periods 1979-1997 and 1998-2018. (b) SBUV merged seasonal average IWC values for 50S-64S, 64S-74S, and 74S-82S. The solid lines show fits for the periods 1979-1997 and 1998-2018. (source)
The long term increase could be the result of increasing CO2, which cools the upper atmosphere while it warms the lower atmosphere. Another possibility includes an increase in atmospheric methane, which gets oxidized into water vapor at high altitudes. Finally, some modelling suggests that climate warming should increase the Brewer-Dobson circulation, which cools the summer mesosphere (more on that, below).
Anecdotally, the most dramatic increase has been at mid-latitudes where no previous reports of NLC sightings exist. In the last couple days NLCs have been observed as far south as Joshua Tree, CA (34 deg. N) and Albuquerque, New Mexico (35 deg. N). There is no historical record of NLC sightings, anywhere, before 1880.
One of the interesting things about the mesosphere where NLCs form (and something which will mess with the heads of some here who like to argue with me) is that the summer hemisphere is colder, and the winter hemisphere warmer, in the mesosphere.
If only radiative heating by the sun (and cooling by greenhouse gases…anything that gains energy from the sun must have a way to lose that energy) were responsible for mesospheric temperatures, the opposite would be true, with the summer hemisphere being warmer, as it is in the troposphere and stratosphere.
The reason for the reversal is the Brewer-Dobson circulation, which causes upwelling (and thus adiabatic cooling) in the summer mesosphere. which That rising air forces subsidence (sinking air, and thus adiabatic warming) in the winter hemisphere.
This hemispheric difference is clearly seen in upper mesospheric temperatures from channel 20 on the DMSP SSMIS instrument. These data are not widely available, and this pair of images, one year apart, was provided to me by Steve Swadley at Naval Research Laboratory – Monterey.
SSMIS imagery courtesy of Steve Swadley, NRL-Monterey.
SSMIS 60 GHz imagery of upper mesospheric temperatures one year apart shows slightly cooler temperatures in 2019 than 2018, presumably leading to more frequent noctilucent cloud sightings.
The SSMIS imagery can’t be directly related to NLC sightings because it is a vertical average for a fairly deep layer in the upper mesosphere, while NLCs form in only the very coldest layer in the upper part of that deeper layer, at the “mesopause”. But I would wager they are correlated.
I think some clever manipulation of this SSMIS channel with the one below it could provide a useful monitoring tool for NLC formation. The SSMIS instruments have been flying since before the last solar minimum, so it would be interesting to see how much colder the current solar minimum is than the last in the mesosphere. I’d love to do this myself, but considerable time would be required for data downloading, reading, analyzing, and displaying the data, and I already have a day job.
One or two oil tankers near the Strait of Hormuz were hit by torpedoes or mines this morning. I checked the NASA Worldview website to see if NASA’s MODIS imager on the Terra satellite picked it up. I had to enhance the image to bring out the dark smoke against the dark ocean background:
Over the next few weeks, mid-latitude observers might experience the best noctilucent cloud viewing of their lifetimes.
Extremely high-altitude noctilucent (night-shining) clouds viewed from Corvallis, Oregon on June 10, 2019 (Tucker Shannon, Google Pixel phone).
Observers over the northern half of the United States are reporting something they have never seen before — electric-blue noctilucent (night-shining) clouds. They are wispy in appearance, and continuously change shape. They can be seen when the sun is about 6 to 16 deg. below the horizon, so about 1 to 2 hours after sunset or before sunrise. During that time of night the sun is still shining on these clouds, but not on any normal weather-related clouds.
In the late spring every year, people at far northern latitudes have often seen these on clear or partly-cloudy evenings. But solar-minimum conditions, with few if any sunspots, are causing cooling in the extreme upper atmosphere around 80 km (~50 miles) high where the lowest atmospheric temperatures are recorded, approaching -150 deg. F (-100 deg. C). That altitude is above 99.999% of the air in the atmosphere.
Noctilucent clouds observed from the International Space Station on June 13, 2012 (NASA).
Adding to the spectacular electric blue displays is increasing atmospheric methane, which gets converted to water vapor at these altitudes, and increasing atmospheric carbon dioxide, which causes enhanced cooling of the upper atmosphere. The result is that the conditions necessary for NLC formation are extending farther south than ever before.
The wispy and undulating appearance of the clouds is due to upward-propagating gravity (air density) waves that cause temperatures to rise and fall, and the clouds form in the colder portions of those waves. Ice grows on meteor dust particles, creating a (nearly) outer space version of cirrus clouds. Time lapse photography has been used to show how the clouds change shape as the gravity waves well up through the extremely cold upper mesosphere:
If you miss seeing them in the next several weeks, take heart — solar minimum conditions should persist until the next NLC season arrives, making the summer of 2020 a good viewing opportunity, too.
You can see recent NLC photos from around the Northern Hemisphere, updated daily, here.
Abstract:A simple time-dependent model of Earth surface temperatures over the 24 hr day/night cycle at different latitudes is presented. The model reaches energy equilibrium after 1.5 months no matter what temperature it is initialized at. It is shown that even with 1,370 W/m2 of solar flux (reduced by an assumed albedo of 0.3), temperatures at all latitudes remain very cold, even in the afternoon and in the deep tropics. Variation of the model input parameters over reasonable ranges do not change this fact. This demonstrates the importance of the atmospheric “greenhouse” effect, which increases surface temperatures well above what can be achieved with only solar heating and surface infrared loss to outer space.
As a follow-up to yesterday’s post regarding why climate scientists use ~340 W/m2 as the global average solar flux available to the climate system, here I present a model which includes how the incident solar flux (starting with the 1,370 W/m2 solar constant) varies across the Earth as a function of latitude and every 15 minutes throughout the diurnal (day/night) cycle.
I am providing this model to avoid any objections regarding how much solar energy is input into the climate system on average, how that averaging should be done (or whether it is even physically meaningful), whether the nighttime lack of any solar flux should be excluded from the averaging, whether certain assumptions constitute a “flat-Earth” mentality, etc. Instead, the model uses the actual variations of the incident solar radiation on the (assumed spherical) Earth as a function of latitude and time of day. For simplicity, equinox conditions are assumed and so there is no seasonal cycle.
This is not meant to be a realistic model of regional climate; instead, it goes beyond the global averages in the Kiehl-Trenberth energy budget diagram and shows how unrealistically cold temperatures are when you assume there is no greenhouse effect — even in the deep tropics during the afternoon. The model “evolves” the final temperatures, from any starting temperature you specify, based upon a simple energy budget equation (energy conservation) combined with an assumed surface heat capacity. Imbalances between absorbed solar energy and emitted IR energy cause a temperature change which eventually stops (in a long-term average sense) when the daily rate of emitted IR energy equals the daily absorbed solar energy.
The time-dependent model has adjustable inputs: the solar constant (1,370 W/m2); an albedo (for simplicity assumed 0.3 everywhere); the depth of the surface layer responding to solar heating (using the heat capacity of water, but soil heat capacity is similar); and, the assumed broadband infrared emissivity of the surface controlling how fast energy is lost to space as the surface warms. I set the time step to 15 minutes to resolve the diurnal cycle. The Excel model is here, and you are free to change the input parameters and see the results.
Here’s how the incident solar flux changes with time-of-day and latitude. This should not be controversial, since it is just based upon geometry. Even though I only do model calculations at latitudes of 5, 15, 25, 35, 45, 55, 65, 75, and 85 deg. (north and south), the global, 24-hr average incident solar flux is very close to simply 1,370 divided by 4, which is the ratio of the surface areas of a circle and a sphere having the same radius:
If I had done calculations for every 1 deg. of latitude, the model result would have been exceedingly close to 1,370/4.
If I assume the surface layer responding to heating is 0.1 m deep, a global albedo of 0.3, and a broadband IR emissivity of 0.98, and run the model for 46 days, the model reaches very nearly a steady-state energy equilibrium no matter what temperature I initialize it at (say, 100K or 300 K):
Note that even in the deep tropics, the average temperature is only 29 deg. F. At 45 deg. latitude, the temperature averages -11 deg. F. The diurnal temperature variations are very large, partly because the greenhouse effect in nature helps retain surface energy at night, keeping temperatures from falling too fast like it does in the model.
There is no realistic way to remove the very cold bias of the model without including an atmospheric greenhouse effect. If you object that convection has been ignored, that is a surface cooling (not warming) process, so including convection will only make matters worse. The lack of model heat transport out of the tropics, similarly, would only make the model tropical temperatures colder, not warmer, if it was included. The supposed warming caused by atmospheric pressure that some believe is an alternative theory to the GHE would cause (as Willis Eschenbach has pointed out) surface temperatures to rise, making the surface lose more energy to space than it gains from the sun, and there would no longer be energy balance, violating the 1st Law of Thermodynamics. The temperature would simply go back down again to achieve energy balance (we wouldn’t want to violate the 1st Law).
I hope this will help convince some who are still open-minded on this subject that even intense tropical sunshine cannot explain real-world tropical temperatures. The atmospheric greenhouse effect must also be included. The temperature (of anything) is not determined by the rate of energy input (say, the intensity of sunlight, or how fast your car engine burns gas); it is the result of a balance between energy gain and energy loss. The greenhouse effect reduces the rate of energy loss at the surface, thus causing higher temperatures then if it did not exist.
Home/Blog
