What is meant by 'Earth's surface temperature'?

In summary,Satellite measurements of Earth's temperature have only been in place since the 1970s. The figure of -18 °C is what you get when you consider the amount of solar radiation hitting the Earth, and consider the Earth to be an imperfect black body (reflection of 30%). At equilibrium, you then get a temperature of 255 K. The fact that this is obviously not what is observed means that there is an additional source of heat, which happens to be the atmosphere trapping radiation that is sent back to the ground, making the temperature higher.
  • #1
Graeme M
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Seeking clarification here. As a climate change sceptic, I loosely follow several blogs that offer critical views of the science behind the idea of global warming, but I am not especially across the breadth of the science. One of the things I struggle to understand is the idea of 'surface temperature'. Or more exactly, what is meant by this.

When we talk of the surface temperature of the moon, we are talking about the temperature of the moon's actual surface (or at least, I presume we are). I assume this is inferred from measuring the moon's spectrum of radiation? Without an atmosphere, it is easy enough to establish an actual, and an average, temperature.

The Earth's temperature however, as considered by the various temperature indices, is measured by thermometers. These are generally measuring the air temperature several feet above the surface. They are not measuring any surface at all. This is easy to see by noting the differences in temperature depending on whether the thermometer device is in shade, in direct sun, near a heat source, or if a hot or cold wind is blowing.

I *think* that the sea temps, as measured by water sampling in times past, or Argo floats etc now, are measuring the water temperature itself, hence it is measuring a surface. But surely ocean temps so derived are not directly comparable with air temps over land?

My questions then, are:

1. Is the use of the term 'surface temperature' for the various indices sloppy nomenclature?
2. Should ocean and air temps be combined (if in fact they are)?
3. Is the Earth's average temperature as expressed in terms of the greenhouse effect (ie 14C rather than -18C) derived from these indices, or is it derived from measurements from space of Earth's radiating temperature (as is done for the moon)?
 
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  • #2
Graeme M said:
The Earth's temperature however, as considered by the various temperature indices, is measured by thermometers. These are generally measuring the air temperature several feet above the surface. They are not measuring any surface at all. This is easy to see by noting the differences in temperature depending on whether the thermometer device is in shade, in direct sun, near a heat source, or if a hot or cold wind is blowing.
You are confusing different measurements. Land surface temperature is measured by satellites. Air temperature is what is measured by thermometers.
Land surface temperature is how hot the “surface” of the Earth would feel to the touch in a particular location. From a satellite’s point of view, the “surface” is whatever it sees when it looks through the atmosphere to the ground. It could be snow and ice, the grass on a lawn, the roof of a building, or the leaves in the canopy of a forest. Thus, land surface temperature is not the same as the air temperature that is included in the daily weather report.
Source: http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD11C1_M_LSTDA

Graeme M said:
3. Is the Earth's average temperature as expressed in terms of the greenhouse effect (ie 14C rather than -18C) derived from these indices, or is it derived from measurements from space of Earth's radiating temperature (as is done for the moon)?
The figure of -18 °C is what you get when you consider the amount of solar radiation hitting the Earth, and consider the Earth to be an imperfect black body (reflection of 30%). At equilibrium, you then get a temperature of 255 K. The fact that this is obviously not what is observed means that there is an additional source of heat, which happens to be the atmosphere trapping radiation that is sent back to the ground, making the temperature higher.
 
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  • #3
Thanks for that. I understood most of the major indices to be constructed from thermometers. Satellite measurements have only been in place since the 70s I think? So when we do backwards comparisons, are we not using thermometer derived temperatures? How can these be compared to satellite temps? As I asked above, that would be an apples and oranges comparison wouldn't it? When we look at all the anomaly graphs, we are not using the land surface temperatures described at your link, surely?

In terms of the greenhouse effect, the 255K is the theoretical temperature of an 'imperfect blackbody' at equilibrium with 30% incoming radiation reflected. The average temperature of ~ 288K measured, is what is measured by satellites? Can you show me a source for that? It seems unlikely to me that the global average thermometer measurement would be the same as the satellite measured temperature.

I'm not trying to find fault with anything, just trying to get my head around the meaning of all the temperature indices.
 
  • #4
Graeme M said:
Thanks for that. I understood most of the major indices to be constructed from thermometers. Satellite measurements have only been in place since the 70s I think? So when we do backwards comparisons, are we not using thermometer derived temperatures? How can these be compared to satellite temps? As I asked above, that would be an apples and oranges comparison wouldn't it? When we look at all the anomaly graphs, we are not using the land surface temperatures described at your link, surely?
I'm not a climate scientist, so I can't give any detailed answer. My understanding is that a lot of work goes into trying to harmonize the data, coming from such diverse sources, from satellites to tree ring data.

Graeme M said:
In terms of the greenhouse effect, the 255K is the theoretical temperature of an 'imperfect blackbody' at equilibrium with 30% incoming radiation reflected. The average temperature of ~ 288K measured, is what is measured by satellites? Can you show me a source for that? It seems unlikely to me that the global average thermometer measurement would be the same as the satellite measured temperature.
For the point of the exercise, it doesn't matter which temperature you use as a comparison. For instance, both land surface temperature and air temperature are much higher than the black body back-of-the-envelope calculation.
 
  • #5
Graeme M said:
Seeking clarification here. As a climate change sceptic, I loosely follow several blogs that offer critical views of the science behind the idea of global warming, but I am not especially across the breadth of the science. One of the things I struggle to understand is the idea of 'surface temperature'. Or more exactly, what is meant by this.

When we talk of the surface temperature of the moon, we are talking about the temperature of the moon's actual surface (or at least, I presume we are). I assume this is inferred from measuring the moon's spectrum of radiation? Without an atmosphere, it is easy enough to establish an actual, and an average, temperature.

The Earth's temperature however, as considered by the various temperature indices, is measured by thermometers. These are generally measuring the air temperature several feet above the surface. They are not measuring any surface at all. This is easy to see by noting the differences in temperature depending on whether the thermometer device is in shade, in direct sun, near a heat source, or if a hot or cold wind is blowing.

I *think* that the sea temps, as measured by water sampling in times past, or Argo floats etc now, are measuring the water temperature itself, hence it is measuring a surface. But surely ocean temps so derived are not directly comparable with air temps over land?

My questions then, are:

1. Is the use of the term 'surface temperature' for the various indices sloppy nomenclature?
2. Should ocean and air temps be combined (if in fact they are)?
3. Is the Earth's average temperature as expressed in terms of the greenhouse effect (ie 14C rather than -18C) derived from these indices, or is it derived from measurements from space of Earth's radiating temperature (as is done for the moon)?
I think the Nasa GISS Says quite a bit about it, but the answers do not inspire confidence.
http://data.giss.nasa.gov/gistemp/abs_temp.html
 
  • #6
Graeme M said:
The average temperature of ~ 288K measured,
There we go, doing "average" again. Way back, when developing a program to calculate the need for heating/cooling of an office building, I got hold of one year of official meteorological temperature data for one full year in Oslo Norway. Not the "average" temperature during a day, but actual thermometer readings taken four times a day at fixed hours. Running standard statistics on those gave slightly different "averages" over a year at each time-of-day, but in every case the standard deviation was slightly more than 10°C.

With that background, what do you think about the statement "the average temperature of the Earth has increased by 0.1°C in the last 100 years".
 
  • #7
Svein said:
There we go, doing "average" again. Way back, when developing a program to calculate the need for heating/cooling of an office building, I got hold of one year of official meteorological temperature data for one full year in Oslo Norway. Not the "average" temperature during a day, but actual thermometer readings taken four times a day at fixed hours. Running standard statistics on those gave slightly different "averages" over a year at each time-of-day, but in every case the standard deviation was slightly more than 10°C.

With that background, what do you think about the statement "the average temperature of the Earth has increased by 0.1°C in the last 100 years".
My world is mostly digital now, but used to be very analog. (I know digital is a special case of analog.)
There was something called Signal to Noise ratio. I suspect those same formulas would apply.
 
  • #8
Personally I am somewhat skeptical that we can say much about historical temperature trends considering both the likely daily variation in temperature at any single location and the extent of changes to the record via homogenisation etc.

However my question was more about what 'surface temperature' means. I think DrClaude above is right in claiming that the average temperature of 14C that is usually offered as evidence of the greenhouse warming effect is a satellite measured land surface temperature, but I have never seen a source that indicates that. I'd be interested to see someone cite a legitimate source for that.

Most discussion on blogs talk about surface temperature, but then refer to things like the GHCN or GISS or HADCRUT indices which as far as I know are derived from thermometers. While it is reasonable to measure the atmospheric temps and then offer some idea of global trends, it seems to me that we shouldn't claim that to be the 'surface temperature'. But that's just my thinking on it and as I said I only have a pretty basic grasp of the science.

So refining my questions earlier:

1. Is the 14C average Earth surface temperature that illustrates the greenhouse effect derived from satellite measured SURFACE temperature, or is it from thermometer records?
2. Do we have an historical record of global temperature anomalies derived from the actual land surface temperature measurements which illustrate a trend in same? And how does that compare to the trends shown by the thermometer records? I realize we can only have satellite records from some 30 or 40 years, but that would be a useful comparison just the same.
 
  • #9
Graeme M said:
Personally I am somewhat skeptical that we can say much about historical temperature trends considering both the likely daily variation in temperature at any single location and the extent of changes to the record via homogenisation etc.

However my question was more about what 'surface temperature' means. I think DrClaude above is right in claiming that the average temperature of 14C that is usually offered as evidence of the greenhouse warming effect is a satellite measured land surface temperature, but I have never seen a source that indicates that. I'd be interested to see someone cite a legitimate source for that.

Most discussion on blogs talk about surface temperature, but then refer to things like the GHCN or GISS or HADCRUT indices which as far as I know are derived from thermometers. While it is reasonable to measure the atmospheric temps and then offer some idea of global trends, it seems to me that we shouldn't claim that to be the 'surface temperature'. But that's just my thinking on it and as I said I only have a pretty basic grasp of the science.

So refining my questions earlier:

1. Is the 14C average Earth surface temperature that illustrates the greenhouse effect derived from satellite measured SURFACE temperature, or is it from thermometer records?
2. Do we have an historical record of global temperature anomalies derived from the actual land surface temperature measurements which illustrate a trend in same? And how does that compare to the trends shown by the thermometer records? I realize we can only have satellite records from some 30 or 40 years, but that would be a useful comparison just the same.
The GISS has their averages for the last 134 years,
http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt
But as the included note states,
"sources: GHCN-v3 1880-02/2015 + SST: ERSST 1880-02/2015
using elimination of outliers and homogeneity adjustment
Notes: 1950 DJF = Dec 1949 - Feb 1950 ;"
and
"Best estimate for absolute global mean for 1951-1980 is 14.0 deg-C or 57.2 deg-F,
so add that to the temperature change if you want to use an absolute scale
(this note applies to global annual means only, J-D and D-N !)"
 
  • #10
Svein said:
There we go, doing "average" again. Way back, when developing a program to calculate the need for heating/cooling of an office building, I got hold of one year of official meteorological temperature data for one full year in Oslo Norway. Not the "average" temperature during a day, but actual thermometer readings taken four times a day at fixed hours. Running standard statistics on those gave slightly different "averages" over a year at each time-of-day, but in every case the standard deviation was slightly more than 10°C.

With that background, what do you think about the statement "the average temperature of the Earth has increased by 0.1°C in the last 100 years".
1400 uncorrelated measurements with a standard deviation of 10°C allow to calculate the average with an uncertainty of about 0.3°C. But with your fixed measurements, it is even better - you can define this measurement procedure to be standard, and repeat it every year, completely removing the effects of daily and yearly temperature variations if you compare two different values.
 
  • #11
1. Question 1

The average surface temperate of the Earth (globally) for a year, is a calculated statistic, that relies upon these measurements and calculations:
1. An average of daily local temperate at a given place (e.g. a minimum and a maximum temperature in 24 hours).
2. An average of those daily temperature averages at that place for a calendar year (say 365 days), for that given place.
3. An average of these calendary year average temperatures for locations distributed over many places on the surface of the earth, at different longitude and latitude.
In addition, there will be some local adjustment of temperature data if it is considered to be affected by local factors that are not of interest to the global statistic being measured.

The above approach is the one commonly adopted by meteorological stations, which are in the business of collecting this sort of data and so that tends to get used. The daily average temperature is based on the minimum and maximum temperatures that they routinely collect. The various research institutes will have an affiliation with these sort of data collectors, then the information is collated into databases for further analysis and use.

Temperature anywhere on the Earth varies with altitude, place and time of day. So on a city street, in summer, during the day, the ground itself might be say 70C, and the air above it 35C. At the same time, the ground temperature in a nearby grass park might be only say 30-35C, or 25C in the shade, and the interior of a car might be closer to 60-70C. As you go higher in the atmosphere, the air temperature will drop until it is below freezing temperature for water, which is where we will find clouds and ice if there is moisture in the air.

The convention is that surface air temperature (measured by thermometers inside Stevenson screens at places like met stations and airports) is measured about 1.5 to 2m above the ground surface. The temperature statistics and the averages that are gathered only make sense based on that assumption. You do not have daily data collection saying that the maximum temperature today was 70C, even though the ground actually did reach that temperature. The daily statistics, used for daily weather reports and predictions are just the air temperature, which is what most people are concerned with for comfort and daily activities.

Due to the averaging process, and the fact that temperatures are often latitudinally distributed due to the rotation of the Earth and the angle of incidence of the sun (i.e. warmer near equator, cooler toward the poles, and reasonably consistent across latitudes), the global average temperature statistic that is produced can also be viewed as a kind of representative number for the average daily (air) temperature that might be expected in the mid-latitudes, averaged over the course of a year. A number of about 15C (288K) suggests that the air temperature is quite pleasant during the day in mid-latitudes, assuming that the daily range of temperatures is not too great (e.g. if it is 7 to 10C variation from that average either way).

2. Question 2

It depends. In practice, they seem to be by the research organisations (e.g. the GISS global averages). See this URL : http://data.giss.nasa.gov/gistemp/ and here : http://data.giss.nasa.gov/gistemp/graphs_v3/

Should they? If you are measuring air temperatures, probably not a good idea to combine them. If you are measuring temperature at a particular altitude (e.g. sea level), you could if you wanted to be consistent.

3. Question 3.

The Earth's global average temperature in the vicinity of 14C or 15C is derived from observations near the surface of the earth. These could be from land based or sea-based observations. For example, in Svente Arrhenius' 1896 paper : "On the influence of carbonic acid in the air upon the temperature of the ground.", he used temperature observations of others to calculate the average global temperature statistic for himself, based on specific latitudes and seasons. This is an example of Steps 2 and 3 I have referred to in answer to question 1.

The "greenhouse effect", as it is known, is a statement of the issue that presents itself when physical scientists try and predict what constant temperature the Earth should be from a general theory about the incoming solar radiation. So the -18C (or 255K) that is referred to, is the temperature that scientists have predicted the Earth should obtain, independently of observations.

The 255K temperature is based on the assumption that the Earth receives all of the sun's directional energy (e.g. 1367 Watts per metre squared on average, for the cross-sectional shape of the Earth i.e. a circular disk), and then warms uniformally to a temperature that allows the Earth to emit all of this energy outward from four times the surface area. Due the physical uncertainty of how this would happen, sometimes it is said that the Earth simply redistributes this energy instantaneously, or is a "perfect thermal conductor". The theory assumes there is some solid surface to work with. It doesn't distinguish between an atmosphere, ocean or solid ground.

Scientists have tried to explain the difference between 255K (predicted) and 287/288K (calculated, based on observations) not so much by examining the initial assumptions again, but by suggesting that there is a period where energy builds up and remains in the system long enough to warm the lower levels of the atmosphere, and then later settles down into a cycle where energy is released to space from the higher altitudes in the atmosphere at a lower rate due to the lower temperature.

So to summarise:
(a) in making the initial predictions that there was some temperature difference between theory and observation to explain, the 255K was a prediction about the surface temperature at the ground surface (in theory, but not observed)
(b) in explaining the current situation, the 255K is used as a theoretical emission temperature, but using a "surface" that is higher in the atmosphere.
(c) observations will not actually find a uniform 255K temperature in the atmosphere above the Earth since temperature is not uniform at a given altitude; rather it will again need to be calculated as an average from different places and times.
 
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  • #12
upload_2015-3-19_7-55-37.png
Here is the daily noon temperature over a year (Oslo, Norway, 1969)
 
  • #13
mfb said:
1400 uncorrelated measurements with a standard deviation of 10°C allow to calculate the average with an uncertainty of about 0.3°C.
I did not say or imply "1400 uncorrelated measurements with a standard deviation of 10°C". What I have is, for each day of the year, the temperature at several fixed time points. Due to the format of the data (think a massive FORTRAN FORMAT statement). it is easy to calculate the average and the standard deviation for each time point, but really hard to calculate the total average and standard deviation. Thus, what I have calculated is the average and the standard deviation for each time point during a year. Most of these standard deviations (of 365 temperatures) are between 10 and 11 degrees*. Using the rule for compound standard deviation, the standard deviation of the aggregate is also between 10 and 11 degrees.

*The sole exception is the measurements taken at 7 o'clock in the morning, where the standard deviation was between 8 and 9 degrees.
 
  • #14
It does not make sense to talk about the standard deviation of a single measured temperature value (unless your temperature sensor is really bad). Do you mean the standard deviation in the set of measurements for a specific time of the day?
The number of 10 degrees is the width of your distribution - you can determine the mean much better than this width. And if you pool the different times of the day for a combined average, you get an even better estimate for the mean.
 
  • #15
CraigAU said:
1. An average of daily local temperate at a given place (e.g. a minimum and a maximum temperature in 24 hours).
See Berry, Bollay, and Beers, Handbook of Meteorology, pp. 540-2, for state of the art circa 1945.
 
  • #16
Thanks CraigAU for your explanations, however I am not certain you quite tackled where I am coming from. I freely admit I might misunderstand the matter so much that my question is just silly. Perhaps it is better if I posed this in the Physics forum as I can see we are getting more into that field.

I will give that a go.
 
  • #17
Graeme M said:
misunderstand the matter so much that my question is just silly.
Not really --- this is more a matter of there being no operational definition consistent with the available meteorological methods and records.
 
  • #18
mfb said:
Do you mean the standard deviation in the set of measurements for a specific time of the day?
Yes. See post #13.
mfb said:
And if you pool the different times of the day for a combined average, you get an even better estimate for the mean.
The mean of what?
 
  • #19
Svein said:
The mean of what?
The mean of all temperature values.
 
  • #20
mfb said:
The mean of all temperature values.
The mean of all temperatures is about 4°C with a standard deviation of about 10°C.
 
  • #21
Svein said:
The mean of all temperatures is about 4°C with a standard deviation of about 10°C.
That is the standard deviation of the sample, not the standard deviation of the mean. Standard error of the mean
If it is still unclear, we should split this thread because it is drifing off-topic.
 
  • #22
If Earth were in pure radiative equilibrium, there would be a temperature discontinuity between the air just above the ground, and the ground itself. In some circumstances (like an inversion in certain locales), you can actually see this happen, with temperatures different by several tens of K between the ground and the air one millimeter over it. But in most circumstances, convection and conduction reduce the discrepancy to a tiny fraction of a degree. The two-meter temperature is just to have a uniform standard, but there are measurements of the surface temperature itself by thermometers stuck in the ground.

There have been enough temperature measurements around the world to get a good idea of the M-GAST (Mean Global Annual Surface Temperature) since the 19th century. Arrhenius used a figure of 15 C (288 K) in 1896, and all the estimates made since then are between about 287 and 288 K. Some global warming deniers say the M-GAST is artificial, wrong, or "meaningless," since they can come up with elaborate mathematical alternatives, but it's easy to dispose of that kind of objection with a few simple thought experiments. Like, which has a hotter surface on average, Earth, or Venus? Which has a colder surface on average, Earth, or Mars?
 
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  • #23
Svein said:
what do you think about the statement "the average temperature of the Earth has increased by 0.1°C in the last 100 years".
I would say it is at odds with the available data. NOAA puts it at 0.85°C from 1915-2015.
 
  • #24
B Levenson, why would your thought experiments cast doubt on claims that a global average surface temperature is 'meaningless'? I'm not sure I see the connection? Without knowing the numbers, clearly Venus would be hotter being closer and Mars colder being further away. But what can that possibly mean for the question of whether a global average has meaning?

Mind you, I'm not sure why a global average might be meaningless anyway...
 
  • #25
haruspex said:
I would say it is at odds with the available data. NOAA puts it at 0.85°C from 1915-2015.
You call it data. I call it an estimate. When I had measurement theory in First-year University Physics, we were taught that the standard deviation of a series of measurements is an estimate of the measurement accuracy. Therefore, I have nothing against 0.85°C, but I would just as easily agree with 0.3°C or -0.57°C.
 
  • #26
No, the standard deviation of this 0.85°C value is significantly smaller, it does not allow 0.3 K or even negative values.

Maybe this concept is easier to understand with body heights: you have a wide range of roughly 1.5m to 2m for adults (with a few outliers) - with a standard deviation probably around 10 cm. If you measure 1000 persons, you can find the average much more precise than "it has to be somewhere between 1.5m and 2m". Actually, you can estimate it with a precision of 10cm/sqrt(1000) = 3mm. If you measure 10000, your uncertainty goes down to 1mm.

If you take tens of thousands of temperature values, your estimate for the average gets very precise.
 
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  • #27
It is the same set of temperature references you get in your local TV and radio weather reports plus thousands of other ground weather stations. For instance virtually every electrical substation in the country has a basic weather conditions instrument set measuring site temperature, humidity, dew point, precipitation, wind speed, and barometric pressure over rural and urban areas. I install command and control room systems for utilities among other things. It is fascinating to watch in real time the shifts in readings as micro fronts pass through a service area along with real time doppler radar overlays and various satellite image overlays when they want to see them.
Satellites can't directly measure surface temperatures at all. They take infrared photos which have to be referenced locally to ground stations and evaluated for atmospheric conditions to determine what is reflected off the atmosphere vs what is radiated back from the surface. Some satellites collect radio telemetry data from remote ground stations, especially several thousand floating and stationary anchored sea buoys that directly measure water temps from the surface to as deep as 1500 meters. NASA and NOAA collect these readings every half hour. There are also thousands of soil temperature readings taken mostly by agriculture researchers on a regular basis too. You can go to NASA or NOAA and download the raw temperature data and infrared photos from the GISS satellites and from ground networks if you feel like wading through a few million data points over say a decade. You can find data sets by specific locations for any day or any year from the present going back over 60 year or more and plot your own local trend maps over decades if you wish too. It is all there with some pretty neat evaluation tools for charting the numbers and trends over both long and short time frames. It is trends in both high/low variability as well as averages over millions of readings over decades that give us a reasonable picture of what is happening to climate conditions.

But the basic physics underlying carbon forced warming theory has been repeatedly tested and verified in lab experiments and real world observations by thousands of physicists going back to Tyndal's measurements of spectral characteristics of gases in the 1850's. What is causing the current rapid warming shifts is the relative balance of incoming solar energy absorbed at the surface everyday vs radiating back into space. The chemical and particulate composition of the atmosphere is what regulates this. We see blue skies on a clear day because long wavelength energy is absorbed, refracted , and scattered back into space while short wavelength energy is transmitted and absorbed, heating the surface of land and water. This surface heat is radiated outward into space at infrared long wavelengths that are absorbed and scattered going out just like they were coming in. Excess absorbed energy is stored mostly in the oceans which play a large role in determining climate effects in the short and medium term time frames. We know with a reasonable degree of accuracy given the enormous amounts of energy involved what the imbalance between incoming and outgoing thermal energy is over time. One German climate researcher described the excess heat absorbed since CO2 exceeded 350ppm in the 1980's as the thermal equivalent of a Hiroshima bomb going off in the Pacific ocean every second of every day for the last 30 years.
 
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  • #28
I am glad to see that my question has at least uncovered a complexity of interest. I am not sure I have been answered but there are fruitful lines of enquiry to pursue.

A question for Drasberry. I have seen that scary statistic before but have no sense of its value. How many Hiroshima bombs per second per day is the energy of the total pacific ocean? How many Hiroshima bombs worth of energy per second per day are absorbed in total?
 
  • #29
Graeme M said:
I have seen that scary statistic before but have no sense of its value. How many Hiroshima bombs per second per day is the energy of the total pacific ocean? How many Hiroshima bombs worth of energy per second per day are absorbed in total?
Your units are totally messed-up there: energy per second is power. Per second per day is nothing. So if I can change the question to be consistent, how about the energy absorbed by the ocean from the sun, per second (just power):
Earth's total solar irradiance: 170,000 terawatts
http://en.wikipedia.org/wiki/Solar_constant#Solar_irradiance
Pacific Ocean fraction: 33%
Albedo: .06
Total power: 53,000 TW

Hiroshima bomb energy: 63 TJ. So that's 837 Hiroshima's per second.
 
  • #30
Sooo... CO2 adds about .12% to the total energy absorbed by the Pacific Ocean?
 
  • #31
I would like to add that gas law contributes to surface and near surface air temps. Not all the difference between the temp expected with "black body" calculations regarding the contribution of sunlight without the greenhouse effect and observed temperatures is due to the greenhouse effect. Any attempt to represent such is misleading and uninformed at the least and intentional obfuscation at the worst.
Any gas under pressure will produce heat. This is actually calculable using gas law.You can calculate specifically what the temperature should be at sea level with the known factors of atmospheric pressure...
Most of the temperature difference between the -18C discussed above and observed sea level temps is due to gas law...not the greenhouse effect.

Simple physics.
 
  • #32
The purpose of averaging is to reduce the information to something discussable... The scales of fluid motion and heat transfer in the atmosphere range from many 100s of miles, to millimeters, with timescales of years to seconds. How much data is too much? You have to filter it somehow to come up with a general pattern and one method of doing that is an average.

While an average may not make sense initially because you have these space and time fluctuations, knowing something about fluid mechanics helps understand why using the "average" might be useful.

Most motion in the atmosphere is driven by two gradients: the pressure gradient and temperature gradient. If the global average rises, these gradients do not necessarily change. However, notice what we are seeing is higher temperature gradients which are producing "strange weather", especially in the US. I live in the north east and this is one of the coldest and longest winters I remember. In 2010 we got a freak ice storm in October that killed all our trees in our front yard.
 
  • #33
Bruce Bracken said:
Any gas under pressure will produce heat.
Compressing a gas heats it, but a gas under pressure (whatever that means, as a gas always has a pressure) does not produce heat.

Bruce Bracken said:
This is actually calculable using gas law.You can calculate specifically what the temperature should be at sea level with the known factors of atmospheric pressure...
Can you explain?

Bruce Bracken said:
Most of the temperature difference between the -18C discussed above and observed sea level temps is due to gas law...not the greenhouse effect..
This goes against accepted science.
 
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  • #34
Bruce Bracken said:
I would like to add that gas law contributes to surface and near surface air temps. Not all the difference between the temp expected with "black body" calculations regarding the contribution of sunlight without the greenhouse effect and observed temperatures is due to the greenhouse effect. Any attempt to represent such is misleading and uninformed at the least and intentional obfuscation at the worst.
Any gas under pressure will produce heat. This is actually calculable using gas law.You can calculate specifically what the temperature should be at sea level with the known factors of atmospheric pressure...
Most of the temperature difference between the -18C discussed above and observed sea level temps is due to gas law...not the greenhouse effect.

Simple physics.
This is a gross misunderstanding.
As DrClaude points out, merely being at a higher pressure does not generate heat. You may be confused by what is known as the lapse rate.
In the absence of a greenhouse effect, there would be little to prevent the entire atmosphere being at the same temperature. An atmosphere of just nitrogen, say, would not be efficient at either absorbing or emitting radiation at visible and IR wavelengths. Conduction would bring the whole atmosphere to roughly equal ground temperature, creating a permanent 'inversion'.
Atmospheric convection arises because the water vapour (and CO2) can emit IR, cooling the upper atmosphere. But the convection is not able to bring the atmosphere back to a uniform temperature because of the gas laws. Descending air warms and rising air cools, so there is a minimum temperature gradient required to drive the convection. That's where the lapse rate comes from.
An analogy that may help is sand piled up on a beach by wave action. Gravity 'tries' to level it out again, but its effect is limited by the stack angle of the sand grains. If the waves get better at adding sand to the beach, the slope of the beach does not increase. Instead, the beach grows broader.
In the same way, an increased greenhouse effect would raise the height of the tropopause. I mention this because I've seen people calculate the surface temperature from the lapse rate and tropopause height, and 'conclude' that the surface temperature cannot change.
 
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Bruce Bracken said:
This is actually calculable using gas law.You can calculate specifically what the temperature should be at sea level with the known factors of atmospheric pressure...
DrClaude said:
...
Can you explain?
I think the poster must be referring to the ideal gas law $$ T = \frac{PV}{nR} = \frac{(1atm) (22.4L)}{(1mole)(0.082 \frac{atm∙L}{mol∙K})} = ~273K $$

and not allowing that if heat enters or leaves the system that both pressure and temperature could change simultaneously under the law, or the atmosphere can expand / contract and allow the pressure to remain 1 atm though the temperature changes and so on.
 
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