## Precipitation to 2% – I don’t think so Jim…

I’d originally set out to figure out how many Watts / square meter were being moved by a hurricane. I may still make that posting some day (it’s an interesting thing…) but along the way reached a different interesting point.

It all hinges on how much heat is moved by precipitation, and to what degree of precision is the global precipitation known?

Can we really say anything at all about “forcing functions” and “heat gain” and “global warming” from CO2 if we are assuming static something that is very much non-static? And what if it has a magnitude that is significantly larger than the CO2 “contribution”? Could not, then, minor variations in precipitation completely erase any “CO2 signature”? (Not to mention completely mitigate any CO2 impact via a minor change of precipitation levels).

### Precision, Units, and Such

So first, some nice to know numbers and a couple of comments about precision.

First off, I’m going to do a lot of this in calories, then turn it into Joules. Largely because the values in calories are more ’round’ and more convenient. Partly as that’s the way I learned to do it years back. Partly because I’m just not fond of the whole notion of units named to laud dead people instead of being clear and self explanatory. (Yes, I like “cps” or “cycles-per-second” much more than Hz, as it ‘self explains’ and makes it more obvious if you have a ‘units error’ in your problem set-up…)

I am, mostly, going to be rounding things off to the 1 or 2 decimal points. Sometimes to integers. I’m going to be a bit “sloppy” about the precision for the simple reason that anything beyond the first decimal point is a fiction in our global measurements anyway, so it’s really rather a moot point. So ought I to use the “International Steam Table calorie” or the “thermochemical calorie”? ( 4.1868 vs 4.184 joules respectively). Frankly, it just does not matter. Toward the end I do a ‘calories to joules to Watts” conversion and you could use any of: 4.2, 4.18, 4.185, or the two standards and not change the conclusions on Watts/m^2 enough to care. Anyone who really cares can go do it themselves and find out how much time they waste… For most things, I use 4.185 joules / calorie, but for many things I use the “close enough” calorie numbers I learned in high school chem. 540 calories / gram for the heat of vaporization of water. 80 calories per gram for the heat of fusion of ice. 1 calorie / gram for the specific heat of water. (Close enough to the 539.xx where xx can range both sides of the round up/down divide depending on who’s calorie and what all else you assume).

### Into The Numbers Game

OK, how much rain / snow / whatever falls, globally, each year?

Conveniently, there’s a Wiki that has that number so I don’t need to calculate it:

http://en.wikipedia.org/wiki/Precipitation_(meteorology)

Precipitation is a major component of the water cycle, and is responsible for depositing the fresh water on the planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year; 398,000 cubic kilometres (95,000 cu mi) of it over the oceans. Given the Earth’s surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. The urban heat island effect may lead to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally. Precipitation may occur on other celestial bodies, e.g. when it gets cold, Mars has precipitation which most likely takes the form of ice needles, rather than rain or snow.

OK, so it’s 99 cm or just a touch under 1 meter of rain globally. I’ll work out the heat content / flow for 1 M of rain, then adjust by 0.99 later.

So, just for fun, we’ll take a detour through the land of inches as that’s how rain is reported in much of the civilized world ;-) and come back to the cm and meters used in those places that are “fraction challenged” 8-)

Besides, it would be far less interesting to just calculate the total heat of vaporization of a cubic meter of water, and the heat of cooling it 40 C, and pointing out that much got dumped at altitude when it condensed and rained back down… 1000 kg x 40 calories/gram + (1000 kg x 540 calories / gram) = 40,000,000 + 540,000,000 = 580,000,000 calories = (at 4.18 joules or watt-seconds per calorie) 2,424,400,000 Watt-seconds or 2,424,400 kW-seconds, with about 31,536,000 seconds in a year (using a simplified 365 day year…) you get 76.88, or about 77 W/m^2-year of power put into that cubic meter of water, evaporated, condensed at 40 C cooler, and precipitated out. That makes CO2 about 1.5/77 or about 2% of the impact of precipitation (IFF the CO2 impact exists at all as hypothesized…)

(I note in passing that the IPCC chart lacks any “time” dimension, so who knows what they were thinking… IFF they are talking about a 24 hour day instead of a year, the irrelevance of CO2 goes even higher, as a foot of rain really swamps 2 Watts)

Or put another way, we would need to know the global precipitation numbers and their changes (deltas or anomalies) to within 2% in order to say anything about CO2 causing temperature changes. If we don’t have those numbers to that precision AND accuracy, we don’t know squat about what is causing a 2% change in any measured heat flow.

At that point, the posting would be done… So, rather than that, lets wander off through the land of inches (and the odd compound of inches of rain per square meter of surface area) as a kind of “cross check”. It also gives us some nice ‘rules of thumb’ for measuring specific amounts of heat being moved by specific amounts of precipitation in particular places as well. Oh, and I’ll be adding in a bit for the Heat Of Fusion for those cases where the water turns to snow or hail before it starts falling back toward earth.

Why? Well, even if the snow or hail does not reach the surface, the HEAT of fusion was dumped up at the tops of those stratospheric thunderheads and hurricanes, so if the melting happens at, oh, 1000 feet above ground level, it still moved a heck of a lot of heat up into the upper air to be dumped to space.

### Into The Land Of Inches

OK, a small table of numbers. The top row is a set of headings as “delta Degrees C”. So “20C” means that column is for taking water at 20C evaporating it, and condensing it back out at 0C without freezing (or from 30 C condensing at 10 C), in either case, you get the heat of vaporization of 540 c/gm and the 1 c/gm of specific heat x (delta degrees). For 20C, that’s 540 + 20 = 560. Columns with “+fus” in them include the 80 calories/gm of the heat of fusion which would happen if snow or hail forms at the tops of the clouds.

But to get joules we need to multiply it by whichever “standard” you like. I used 4.185 for this chart as it is about in between the Steam Table calorie and the thermochemical calorie. As noted above, it doesn’t really matter as the 3rd decimal place is not really relevant. So 560 x 4.185 is 2473.3 kj for a kg of water (or one liter). (or 2473.3 j/gm). That’s the second line. How many kj is represented by a liter of water that is evaporated, taken up into the clouds, and condensed at a lower temperature (and perhaps also frozen).

As a joule is one Watt for a second, those numbers are also the Watt-seconds needed to heat the water that much. 2.473 kW for a second will warm a gram of water from 0C to 40C and evaporate it (if I’ve not buggered the math somewhere). Oh, and realize that in the real world it will be somewhat more complicated than this as the specific heat of steam is different from the specific heat of water, so the actual values will depend on when it evaporates vs when it heats and when it condenses vs when it cools. As liquid or vapor. But as a first approximation, this gets us close to what’s happening, on an order of magnitude basis at least. We can reasonably presume that if the water was at 40C in the tropical ocean, and was at 0C in the cloud tops as condensed rain, the heat flow was the same as that of the specific heat of that much water, even if it traveled as water vapor in between. We also know the heat of vaporization was taken at the surface, and released somewhere in the cloud as water condensed and rose. (Then transported on up to the tops). Oh, and two ‘nice to know’ numbers are that there are 86400 seconds in a day and 31536000 in a year (more or less, modulo an occasional leap year ;-)

I then take the “plug number” of 25.4 liters of water per “inch” of rainfall per meter squared, and find the number of joules in that many liters of water as being the “joules / inch of rain”. (100 cm on a side is 10000 cc. 2.54 cm / inch, 25400 cc or 25.4 l)

I do the same thing for kW-seconds / m^2 for 10 cm of rain (about 4 inches) so the fraction challenged folks can have a decimalized system for reference ;-)

```20C	40C	20C+fus	30C+fus	40C+fus
2343.6	2427.3	2678.4	2720.25	2762.1	kj/liter

59527	61653	68031	69094	70157   kW-seconds/m^2 per inch of rain

234360	242730	267840	272025	276210  kW-seconds/m*2 per 10 cm of rain

```

OK, that’s a lot of joules, but most folks don’t really have a good handle on what a joule is, and a Watt Second is kind of unfamiliar in normal day to day life, so lets turn it into how many Watts that would take, spread steadily over a whole day, and over the whole year. Just using those ‘seconds / day’ and ‘seconds / year’ numbers to look at the total impact, rather than just ‘what if it all happened in seconds?’

```689	714	787	800	812     W/m^2 in one day per inch

2713	2809	3100	3148	3197    W/m^2 in one day per 10 cm

1.89	1.96	2.16	2.19	2.22    W/m^2 in one YEAR per inch

7.43	7.70	8.49	8.63	8.76    W/m^2 in one YEAR per 10 cm
```

Hmmm… Starting to be interesting. We’ve got about 689 W to 812 W needed over the whole day to evaporate an inch of rain. As the typical tropical earth surface gets a bit over a kW for about 1/3 of the day, we’re looking a each inch of rain representing at least a couple of days of total sunshine if it all reached the surface.

Those total year numbers are also interesting. An inch of rain is about the same as the total CO2 “forcing” (one presumes they really mean “forcing function” and just don’t know how to use the language properly…) attributed to CO2. The flip side of this is that it implies we MUST know the global rainfall to less than one inch of both accuracy and precision to be able to say anything at all about the heat flow in the size scale of the implied CO2 function. IF we don’t know the precipitation that accurately, we don’t have a clue if things are warming, or being taken to space by thunderstorms… OR if any measured warming is just from a bit less rain this decade… Which is the cause and which is the effect is opaque if you lack that data. In short, you must be guessing and calling it a theory or calling it science. But it’s still a guess if that data is not available.

OK, time for our “cross foot”. We’ll figure the Watts / m^2 for 100 inches of rain, for 1 m of rain, and then adjust that to 99 cm as that’s the actual global average.

```
189	196	216	219	222     100 inches

74.3	77.0	84.9	86.3	87.6    100 cm (or 1 M) of rain
73.6	76.2	84.1	85.4	86.7    99 cm (earth average)

2.0%	2.0%	1.8%	1.8%	1.7%    CO2 at 1.5W as % of precipitation
```

OK, so we’ve got to know the global precipitation and it’s deltas (anomalies) to within less than 2% to know if CO2 is doing anything. Otherwise, it could just be rainfall variation. It is NOT enough to just “assume it doesn’t change”. CO2 might well increase heat gain at the surface, only to have a 1.8% increase in total precipitation wipe out any change of temperature. (Or a slight change in stratospheric temperatures offset it).

I also note that the 77.0 number for 40C non-fusion for a meter of rain is in close agreement with our first cubic meter estimate, so there is some hope I’ve not messed up the math anywhere ;-)

OK, one last little interesting number. Take the two values for ‘with fusion’ vs without at 40C and subtract them. 87.6 vs 77.0 is roughly 11 Watts. That means that a 14% change in how much of the water that falls as precipitation has a “freeze” happen at altitude (regardless of if it reaches the ground frozen or not) can account for the same 1.5% of heat flow as all CO2.

Do we even know what percentage of global precipitation has a freeze event at altitude? If it freezes at 40,000 ft, and melts at 2000 picking up heat down low, how do we even know?

One other complication: Water can cycle high to low to high to low again and never reach the ground. How much variation in that ‘inside the thunderstorm’ heat flow is even known?

### In Conclusion

It looks to me like the error band on precipitation makes it completely impossible to know what CO2 might or might not be doing. It can only be an article of faith. Since we have no clue, really, how precipitation changes happen over the PDO / AMO cycles to 2% of variation, how can we say if any warming or cooling is CO2 induced or precipitation dependent?

Finally, for those who stuck it out through the text and tables, some ‘eye candy’. A few graphs and pictures that give some supportive evidence for some of the numbers I’ve used here and some of the conclusions I’ve reached.

First off, here is what a cyclone looks like from space in infra-red. Notice just how much heat is being dumped at altitude at the top of that thing? It is just a monster cooling pump dumping heat to the stratosphere. So, any guesses as to how many hurricane strengths are known to within 2%?

(This picture was featured in the Wiki on “Tropical Storms” here: http://en.wikipedia.org/wiki/Tropical_cyclone )

Cyclone Monica in Infra-Red

The use of 1.5 Watts as the “CO2 Forcing” is based on this graph:

As found in the wiki on “global warming”. Oh, and they have one on total sunshine here: http://en.wikipedia.org/wiki/Insolation

(Yes, I’m not bothering to make those ‘live links’. If they want to play games with what gets found by their search engine to favor global warming agendas, I can reduce their ‘link count’ metrics by one… What goes around, comes around… )

For what it’s worth, the wiki on heat capacity and enthalpy are fairly decent, even noting many things about heat that I’ve noted before (such as the tendency for averages of temperatures to be a bit daft…) though they persist in the notion that any science using terms or units from less than the last international party, er conference, buggering them, er ‘revamping’ them is “archaic”… Well, I happen to like my science old, musty, archaic, and very well worn. It’s more likely to be right that way. Units are not fashion statements, and it makes not one whit of difference if one uses BTUs, calories, joules, or any other unit.

http://en.wikipedia.org/wiki/Heat_capacity

http://en.wikipedia.org/wiki/Enthalpy_of_fusion

http://en.wikipedia.org/wiki/Enthalpy_of_vaporization

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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### 30 Responses to Precipitation to 2% – I don’t think so Jim…

Units. You’ve done it all in the units you are happy with, and I admit that is how I would do it too. But then I was brung up on Imperial and have an old-fashioned POV that these new-fangled Napoleon units are all very fine in theory but really do not fit with people. However, you and I are dinosaurs, and we can’t even begin to make that sort of argument. When we are gone, those who remain will not even know that units which have natural scale, and are named by their relation to others are easier to use and less likely to result in error.

Nice work on the rain, but surely the final answer is to measure the radiation budget of the whole earth, albedo, outgoing radiation, insolation from space etc to see what is happening, Although I have a fantasy of instrumenting one actual square metre all the way up just to see what is happeniong and how it compares with theory.

2. H.R. says:

Units? Solidarity, brother E.M.

I hate doing calculations in those new-fangled SI units; “Olympic-size Swimming Pools” and “Manahtten Islands.”

3. Ian W says:

There is a NASA page that calculates the amount of energy transported by an ‘average’ hurricane in both water terms and kinetic energy terms per day. In water terms it equates the amount of energy to 200 times the daily world wide total electrical generation power. See http://www.aoml.noaa.gov/hrd/tcfaq/D7.html

More importantly, the global warming community ALWAYS use the Stefan Boltzmann equations for heat leaving the planet and assume such radiation is from the surface and the fourth power of temperature. Latent heat released on condensation and fusion obviously does not follow this law and ‘heat’ is NOT ‘temperature’ so large amounts or radiated latent heat can leave the freezing top of a thundershower. I have never seen this heat included in models. Yet every cloud droplet as it formed radiated heat.
.

4. Pascvaks says:

I really am afraid for you. “They” cannot and will not allow you “free rain” any longer. They will rip you to shreds as soon as this post gets out and circles the globe, four or five times on the web. Don’t tell anyone where you’re hiding or any of your haunts.

Freedom isn’t free! It’s obvious you need a few years in a Kanadian Koncentration Kamp to be “reeducated” in the ways, whys, and wherefores of the New World Order.

Afraid your only hope is to stop using Windex on your toes and just let the fungus grow. They are more freighten of microbes than they are of “counter-revolutionary” blog posts. Good luck Komrade!

(SarcOffaLittleSinceThereIsALittleTruthInEverythingWeSayAndDo;-)

5. Jeff Alberts says:

So is “Global Average Precipitation” another meaningless thing like “Global Mean Temperature?”

6. A K Haart says:

An absolutely fascinating analysis – I’ve not seen it done quite like it before. So now we have yet another monster of an uncertainty lurking in the assumptions.

7. PhilJourdan says:

Fascinating numbers! Fun to play with. But I see the folly of talking about global averages. besides, it would be no fun if Imperial Valley got as much rain as the east coast. ;)

8. Another Ian says:

H.R.
Units? Solidarity, brother E.M.

I hate doing calculations in those new-fangled SI units; “Olympic-size Swimming Pools” and “Manahtten Islands.”

HR

You missed “Football Fields” and “Sydney Harbours”

9. Lemme see now, in the AR4 both clouds and precip are not well known. By any reasonable estimate, a small change in clouds swamps the effect of CO2. You have now done a reasonable job of showing the same for precip.

Yup, IPCC Climate Science IS Junk Science.

Here is a new paper for solar contribution:

http://arxiv.org/abs/1102.4763

10. Rob R says:

Part of the rain fails to hit the ground. It evaporates before it gets there. There is an epicycle going on up in the sky. Please make it stop because its too cold where I live.

11. Owen Hughes says:

Chiefio: Over what unit of Earth surface area does that 990 mm of rain fall? Per square meter? If so, amazing. And that represents a lot of work. How many calories or Joules does it require to lift a cubic meter of water to the “typical” height of rain, say a couple of thousand meters? Is that another way to frame the question?

12. Richard Ilfeld says:

Your new location is going to your head. It rained yesterday. It rained today. It will rain tomorrow. It never rains in California, but……

I can see where rain variation would swamp co2 forcing….but I have lately been spending more time looking at the geologists point of veiw. A 10 or 20 or 50 year trend may be interesting if one is alive for that 10 or 20 or 50 years, but the planets perspective is thousands of millenia. It is a good working theory that all these factors are subject to a tendency towards equlibrium,…as they vary from the norm natural forces tend to push them back.

Every hundred thousand years or so temperature takes an excursion into an ice age, with eventual recovery. There doesn’t seem to be as defined an extreme on the high side. Rainfall probably responds in similar fashion.

Except here in Florida where it rains every day, in season.
Which may have contributed to your minor physical maladies. They send folks
to hot dry climates to get over stuff – here we live in a giant petrie dish & all manner of nasties thrive.
,

13. gnomish says:

good job.
nobody sane can argue with real physics.

14. Joel Heinrich says:

Units. Your post is unintelligible. What is j/gm supposed to be? I assume that you meant J/g.

You can of course calculate in inches and calories or whatever you like, but just why don’t you use the correct spelling for the units? There is a reason why they are what they are. Just think about the difference between mW, MW, and W/m².

Another point I’ve never understood is why you use ‘C’. It is °F, °C, but just K. So, if your keyboard doesn’t have ‘ ° ‘, why don’t you use K instead? Yes, you can (and should) use K for temperature differences.

Sloppy writing leads to sloppy thinking and thus to errors.

15. tony Hansen says:

Joel,
And a pre-conceived commitment to a certain rigidity of thinking can lead one to miss the whole point of the communication.
For me the greatest difficulty has mostly been just trying to get a true and proper understanding of what my interlocutor is trying to convey.
It is not uncommon for them to be strikingly insightful in (at least) one particular area.
Nor is it unusual for me to be significantly blind in some areas.
When things seem “unintelligible”, does the fault lie with thou or thine?

16. Joel Heinrich says:

tony,

“And a pre-conceived commitment to a certain rigidity of thinking can lead one to miss the whole point of the communication.”

And you are leading by example as I see.

I didn’t argue about the content, because that was not my point. My point was exactly the misspelling of the units. The Chifio said that he doesn’t like the SI units, because they are too difficult to understand (or that he doesn’t want to understand or to learn them). Fine, as I said, he can calculate in whatever units he want. I just argued that IF he writes in SI units, then he should do it right, so that it’s easier to understand.

For example, it would be easier to use mm instead of cm, because 1 mm/m² rain equals 1 l/m² (That’s why the Wiki used 990 mm and not 99 cm).

Or as 1 W = 1 J/s then of course 1 Ws = 1 J. So, why use Ws at all?

As for the content: ” We can reasonably presume that if the water was at 40C in the tropical ocean,”
You would really be hard pressed to find a location, where the temperature of the ocean is at 40°C.

AND, the specific enthalpy is not linear. He should take a look at a Mollier-Diagram.

As a result, the numbers are either unrealistic or just wrong. And never mind that a tropical rain isn’t a freezing sleet but warm and pleasing, when not delivered by a hurricane.

17. PhilJourdan says:

@Joel – “My point was exactly the misspelling of the units. The Chifio said …”

How about removing the stud from your eye before worrying about the mote in others. It is Chiefio, not a dessert

18. tckev says:

Excellent job.
Sometime ago I was trying to find average yearly rainfall for particular geographical areas of the world and particular years. I could not find many. Yet that same global average kept appearing everywhere. How have they calculated it?
On measurement –
I don’t give 2 minims of spit for the “new” SI units. They should be kicked at least a league and a furlong into a bushel of horse excrement, (or a hogshead cat’s urine)!
I am firmly of the belief that youths of today are being “dumbed-down” by not learning the old units. With the old units you learn some excellent arithmetic agility (times 12, 8,3, 1/3, 1/8, etc.), while using a very human-centric measurement system that took centuries to put together.
With the decimal system you learn 10 times and tenths and the multiples of them. Simple? Yes.
Good for science and engineering abstract calculations? Yes.
Relates to humans? No.
Back in the days when I was doing a lot more engineering work the calculation were done in SI units but the customer’s eyes always preferred the drawings in the good old English units.

19. TIM CLARK says:

on 7 September 2011 at 6:04 pm PhilJourdan

LOL

20. Svend Ferdinandsen says:

Thanks for the article. I did the same for half a year ago for the same reason that you did.
I incorporated that the condensation energy in the cloud would go half up and half down, and got a figure around 15W/m2 for an average of 1mm/day (a nice figure you can remember). It gives 40W/m2 with 990mm/year.
I can not say which figure is the best, but in the radiation pictures they use 75W for evapotranspiration, and that is more or less your figure.

The end point is anyway, that even small changes in precipation overwhelms the CO2 effect several times.

21. H.R. says:

@Richard Ilfeld

“[…] ….but I have lately been spending more time looking at the geologists point of veiw. A 10 or 20 or 50 year trend may be interesting if one is alive for that 10 or 20 or 50 years, but the planets perspective is thousands of millenia. It is a good working theory that all these factors are subject to a tendency towards equlibrium,…as they vary from the norm natural forces tend to push them back.

Every hundred thousand years or so temperature takes an excursion into an ice age, with eventual recovery. There doesn’t seem to be as defined an extreme on the high side. Rainfall probably responds in similar fashion. […]”

That’s where I’ve been for quite some time. I don’t think there’s much in the way of global climate change until the continental plates significantly change position. The glaciations and interglacials…? That’s just geological weather as the plates have remained pretty much in place during the past 2 million or so years.

anna v, over at WUWT, once posted an old Greek philosopher’s observation that “you can never cross the same river twice.”

So it is with the earth’s climate on geological time scales. The earth is going on a journey from its “birth” until its eventual “death” and it is never exactly in the same position in relation to the universe as it just was the previous moment, regardless of time scale. The geology and geography of the are earth never the same from moment to moment (however long you care to define that moment to be) and never repeat exactly. The atmosphere is constantly changing and never repeats.

On humankind’s timescale, we’ve only seen what amounts to really, really, really bad weather since the first hominids walked upright. No one is going to live long enough to see real global climate change – and I include glaciations in that statement, if one happens to occur very soon – unless we’re around for another super caldera or a major asteroid strike.

That’s my story and I’m stickin’ wid it.

Meanwhile, the mechanics of the climate we have are fascinating, so I love reading and learning more about weather and climate.

22. E.M.Smith says:

@Joel:

Perhaps you are more rigid than most. Not my problem. “g” is the gravitational constant to me. I learned gm as the abbreviation of gram some odd fraction of a century ago. Happy to be “out of date”, if that’s what it is. Btw, I don’t think you can ‘misspell’ an abbreviation as it’s not a word. Don’t know what you would call ‘using a nonstandard abbreviation’ but I’m pretty sure it’s not ‘misspelling’… (which I’m also quite good at as one ought to “never trust a man who can only spell things one way” ;-) Twain, I think… though also some attribute it to Jefferson:

http://www.monticello.org/site/jefferson/spell-word-only-one-way-quotation

http://quoteinvestigator.com/2010/06/25/spelling/

Every single day I run into a dozen “context specific abbreviations”. It’s common and just not much of a problem. Get over it.

Perhaps you would like everyone to only speak French as defined by the French Academy? English is so messy and ill defined…

Further, the yahoos in Europe keep mucking around with what the “units” are that are approved. (Don’t get me started on how they have redefined the “usual” units to use in talking about radiation). Frankly, it’s not worth my time to keep up with them and I feel no need to let them call the tune to my dance.

On a lighter note, a friend (now with PhD in Physics) once finished a physics test with extra time. On it he had answered one question in units of “furlongs per fortnight” as he was a bit bored… One TA tried to downgrade him for it; on appeal the professor gave him extra credit (both for the extra work and for the humor… )

Frankly, you ought to be happy I didn’t do it all in grains, gills, and BTUs… I find BTUs and F easier to work with… btw, I’m sure there is some “magic cord” to get a degree symbol out of a PC keyboard, but I know how to do it on a Mac – where it’s easy – and just don’t have the time right now to learn all the peculiarities of the PC. Don’t like it? Then think about maybe “carping” less and being constructive more. LIke, oh, “The way to get a degree symbol on a WIndoz PC is FOO…”

One final point on this: My POV may be biased as I’ve spent a lot of my life writing computer programs where you are constantly defining new tokens and terms to have location specific meaning. NOTHING is set in stone. Heck, I even wrote a language preprocessor once – a trivial one, so I could write code that looked like “Yea verily doth Overlord smite thee” (that the preprocessor turning into a call to “system” (overlord) to load (smite) a variable (thee) with nulls…. Why? I was a bit bored… So I fully expect that I ought to be able to do a set of declarations then use any symbol I want any way I want… as that is how we do it in my profession. And I’m fine with that.

On Traditional Units: I find I can do fractional math in my head much easier than decimal math. So using units / systems that are ‘factor rich’ just works better. That’s the same reason they were originally made that way too. Paper and calculators being a bit scarce in 1000 BC… So I’ll be happy to use feet and pounds for the rest of time.

@Jeff Alberts:

Global average precipitation COULD have meaning, as it is a specific measurable thing. It “has issues” having to do with how to measure it, but a quart of rain is a quart of rain, and averaged with a gallon it’s a valid average (provided you know the relative areas too…) unlike averaging temperatures where you need the mass and specific heats too… BUT there just isn’t enough data to have a very accurate or precise average precipitation. We simply do not measure giant areas of the globe, especially in the mountains and in the middle of the tropical oceans where a lot of it falls.

THE key point, though, is that the attribution of effect to CO2 is lost in the error bands of the precipitation numbers that are just massively larger, and we can’t just get away with saying “assume it is constant”. Ask West Texas right now…

@H.R.

On a geologic time scale, it is clear that precipitation varies widely and inversely with temperature. It’s the control valve in this system.

@all:

OK, substitute “tropical puddle” or “tropical lake” or “tropical pond” for “tropical ocean”. Whatever floats your boat. 104 F water happens. Call it what you will. You’ve got a range from 20 C to 40 C in the tables to choose from.

@Owen Hughes:

That’s the nominal average of all rain over all surfaces. Some places get up to 400 inches of rain (about 10 meters) and others get near none. Average is about 1 meter. Yup, that’s a heck of a lot of heat transported. See the tables above for “how much”. Note that it’s dominated by the heat of evaporation, so it doesn’t matter much if it’s a 10 C, 20 C, 30 C, or 40 C delta T.

@Rob R:

That’s one of the big error terms on total heat flow. Just how much heat is transported how high by rain that never reaches the ground to be measured?

23. Jason Calley says:

@ H.R. “anna v, over at WUWT, once posted an old Greek philosopher’s observation that “you can never cross the same river twice.”

Or, as Zeno observed, “you can’t even cross it once!”

:)

24. PhilJourdan says:

@EM – “Heck, I even wrote a language preprocessor once – a trivial one, so I could write code that looked like “Yea verily doth Overlord smite thee” (that the preprocessor turning into a call to “system” (overlord) to load (smite) a variable (thee) with nulls…. Why? I was a bit bored…”

I wish you had published that language. It sure would have been fun to work with! :)

25. R. de Haan says:

26. Brian H says:

About the kb ° symbol: for PCs, use Alt-248. ☺ ☻

27. Wayne Job says:

Thank you Mr Smith for your adherence to the real harmonic measuring system that has relevance to the Earth and the universe. The time has escaped metrics as has the circle still based on 60 thank god. Oddly the metric system aligns with nothing and is sterile. I design and manufacture machinery and working in inches makes things easier. When I am finished with pro-types the draftsmen convert it all to metric and the problems begin. It is not easy to read a half a millimeter on a ruler, finding angles in radians is even harder as my tool supplier has no equipment that reads these radians.

In Australia we have the problem of government mandated rules for metric measure. All engineering must be done in milli meters. Factory plans are special when you have buildings that are 1,345,123 long by 560,354 wide it is unimaginably dumb.

28. E.M.Smith says:

@Wayne:

Thanks! Yup, those “too small” units are worse than the “too big” ones that are the alternative. Then again, better than the “constantly changing the approved size” ones in Britain ;-)

IMHO, government ought to be out of the business of mandating how things are measured. Folks can decide for themselves… I do ;-)

29. Mick says:

Thank you for an enlightening study of a hugely important and overlooked cycle. As for the discussion of units, as a physicist, I usually work in the original SI standards (no football fields – which football? soccer, Australian, American?), but give distances in Imperial, and fluids in litres. I prefer an English pint to an American one.
All in all, work with whatever units are easiest for you – you’re the one doing the calculating! Just make sure the conversions are right.