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Martin, the point about Florida was that you used it to counter EM's assertion:

"Basic physics.

Increase the temperature and you increase the water vapour content of the atmosphere. Precipitation increases, and with it flooding."

You replied:

Whenever I have driven down the Florida Keys, it has been around 90° F, with millpond turquoise green sea on either side of the highway, and nothing more than a few wispy white clouds high in the sky.

Obviously "basic physics" (™ EM) does not apply in Southern Florida.

This anecdote implies that Florida is a tranquil place not affected by basic physics and storms. But the image I posted (https://community.fema.gov/sites/default/files/hurricanemap750w.jpg) makes clear that the southeastern states in the US get far more hurricanes and tropical storms than the rest of the US. Maybe you were just lucky (my single visit there was equally nice). Or maybe storms occur more in summer when it is hotter. The fact that Florida is a favourite winter vacation destination may just indicate that it gets fewer storms in winter or that even the risk of storms is preferable to getting snowed-in in New England.

This doesn't prove EM's assertion, the map shows that southwestern US, which I imagine is similarly hot, does not get so many hurricanes. There is clearly more to storm formation than just temperature - an 'insight' that is a commonplace. But objecting to EM's assertion on the basis that you had some nice holidays in Florida seems a little unscientific.

Dec 16, 2015 at 1:54 PM | Unregistered CommenterRaff

But objecting to EM's assertion on the basis that you had some nice holidays in Florida seems a little unscientific.

Raff - an unscientific assertion does not require a scientific objection.

EM said

Basic physics.
Increase the temperature and you increase the water vapour content of the atmosphere. Precipitation increases, and with it flooding.

The fact that EM prefaced what he said with the holy incantation "Basic physics" does not in fact make his sentence into a scientific truth like (pulling an example out of the air) the relation between the energy of a photon and its wavelength. It's obvious that it applies in some situations but equally obvious that it does not apply in some other situations.

Equally "basic physics" EM could have said:

Increase the temperature and you :increase the water vapour content decrease the relative humidity of the atmosphere. Precipitation increases decreases, and with it flooding."

So why did EM come up with his comment rather than the equally valid one that I have just given? It's because, very clearly, something will come into EM's mind and, if he likes the look of it, it then becomes part of his internal reality. At that point, EM will then present it to the world as if it is really reality.

EM's comments, many many times have shown that, for him the weather/climate system is something that follows simple rules and can be reduced to simple formulas understandable to a 16-year old science pupil.

Neither you nor he should expect everybody else to share his simplistic view of how things work. The fact that the Met Office equipped with staff in the hundreds, supercomputers, and million line Fortran programs does not have much of a clue how it all works should be a hint that perhaps EM's views are - - - a bit simplistic.

Dec 17, 2015 at 11:02 AM | Registered CommenterMartin A

Due to my inferiority complex, I usually find it a bit intimidating when people start with "it's basic physics...". But people here often say the same about economics, about which I know enough to know that those using "its Economic-101" know no more and probably a lot less than Economics-101. I'm not so good at gauging people's physics level.

Increase the temperature and you decrease the relative humidity of the atmosphere. Precipitation decreases, and with it flooding.
Is that basic physics (just asking, I don't know)? I can read that a temp increase on its own increases the equilibrium partial pressure of water and reduces relative humidity. But I thought that warmer air will lead to more evaporation and hence more water in the air (even if RH is reduced). And being naive, I imagine that the global precipitation depends upon the total amount of water in the atmosphere, not the relative humidity - that rain depends upon local conditions, not the global average humidity. Is that all wrong?

Dec 17, 2015 at 2:09 PM | Unregistered CommenterRaff

Raff - as I indicated, I think it goes both ways. Warmer means (a bit) more evaporation, so possibly more rain. But warmer also means that, for a given atmospheric water content, the RH falls.

For clouds to form, the RH has to be 100% (or more - ie air supersaturated with water vapour). If the water droplets that constitute clouds were to find themselves surrounded with air of less than 100% RH, they would evaporate and the cloud would disappear. This can often be seen in real life.

So, if the RH of the air above some land area is reduced to to something less than 100%, no clouds, therefore no rain above that area.

imagine that the global precipitation depends upon the total amount of water in the atmosphere I very much doubt that there is a simple relation between the two.

Dec 17, 2015 at 3:08 PM | Unregistered CommenterMartin A

Yes I can see that if RH over an area decreases that could reduce cloudiness. But air doesn't stay put - that air will move somewhere colder, its RH will increase and clouds may form. And as the air in total hold more water it would be reasonable to assume more clouds and rain somewhere. The distribution may well change.

"I very much doubt that there is a simple relation between the two" [global precipitation and the total amount of water in the air]
But you said earlier that it is basic physics that increasing the temperature decreases the relative humidity of the atmosphere and decreases precipitation. Meaning that it is basic physics that global precipitation is directly related to RH but not to the total amount of water in the air. Can that really be true?

Dec 17, 2015 at 3:37 PM | Unregistered CommenterRaff

increasing the temperature decreases the relative humidity of the atmosphere and decreases precipitation.

yes I think I said that.

Meaning that it is basic physics that global precipitation is directly related to RH but not to the total amount of water in the air. Can that really be true?

No it does not mean what your first sentence says. RH is purely a local thing. It would be completely meaningless to talk about RH globally. It's not a thing where averages have any meaning. If the RH in a particular area went down, you'd expect less rain there.

But the same water vapour that passed over that area without falling as rain because of low RH might well finish up as rain falling somewhere else, maybe over the sea somewhere.


imagine that the global precipitation depends upon the total amount of water in the atmosphere (Raff)
I very much doubt that there is a simple relation between the two.(Martin A)

When I said that I meant what it said. That I don't think there is a simple relation, even an unknown one, between global precipitation and the total amount of water in the atmosphere. That is because there are all sorts of different ways of having a given amount of water distributed through the three dimensions of the atmosphere. Some distributions could result in much more total precipitation than others.

By "relation" I think I mean more or less something that can be written as a mathematical formula.

Dec 17, 2015 at 5:42 PM | Registered CommenterMartin A

Raff, just to try to clarify, what I was saying about what EM said was that it is not clear cut whether increasing temperature would

(A) cause increased rain and flooding (EM)
or
(B) result in reduced precipitation (at least in some areas) (MA).

So neither one nor the other has a claim to truth as "basic physics".

I've always imagined that, once the Sahara became a desert, it was stuck like that, with hot air rising from the hot sand (with no clouds to shield it from the Sun so getting *very* hot) preventing the formation of clouds despite winds from the Atlantic passing over it. That would be an example of "hotter" not resulting in "more rain, more flooding". Possibly more convincing than Florida on a fine day?

Ever read "The Drought" by J G Ballard? A man-made climate disaster novel.

Dec 17, 2015 at 6:51 PM | Registered CommenterMartin A

Sandy,
You have pegged Raf on the fundamental intellectual dishonesty at the heart of so many climate fanatics.
The world must change completely to unreliable, provably poor alternative energy systems that are also costly to consumers. The world must impose a climate imperialism on the third world for their own good of course. And no one can question these things without proving they are evil and wicked. But when asked for specifics about this climate imperium, the science behind it, the risks to be averted, the costs, the crisis that must exist to justify this huge imposition of impoverishment, all Raff can do is to run away and distract.
He is a mini-me example of the cowardice at heart of many in the climate obsessed community.
Good job in getting Raf to provide such excellent demonstrations.

Dec 17, 2015 at 10:00 PM | Unregistered Commenterhunter

Martin A,
Have you read "The Day of Creation" by Ballard? in a way another African climate novel, but with some interesting excursions into human frailties. Sort of an homage to "Heart of Darkness".

Dec 17, 2015 at 10:11 PM | Unregistered Commenterhunter

hunter - I have The Day of Creation on my bookshelf. I must have another go at reading it. Except for The Kindness of Women, I've never got on well with J G Ballard's later novels (after Crash and The Atrocity Exhibition). For me they don't have the magic of his early work.

In contrast, his short stories, his essays and his reviews have always been wonders of deep insight and astonishing originality. To my surprise A User's Guide to the Millennium: Essays and Reviews is still available from Amazon - even a used copy at £0.01 is on offer.

Dec 18, 2015 at 9:59 AM | Registered CommenterMartin A

Martin A

Think of the atmosphere as a capacitor. Relative humidity is equivalent to the % of charge in the capacitor. Increasing temperature is equivalent to increasing the size of the capacitor.

Dec 19, 2015 at 9:28 AM | Unregistered CommenterEntropic man

EM - As I have said before, you love stating the obvious as an analogy that adds nothing. Not sure why you keep doing it.

Dec 19, 2015 at 11:00 AM | Registered CommenterMartin A

Martin A

Because increasing the water vapour content and latent heat content of the atmosphere by increasing temperature forces increased precipitation. This outweighs any RH change.

Dec 20, 2015 at 9:14 PM | Unregistered CommenterEntropic man