Mesoscale Meteorological Modeling

Rating:
Summary: Yes, but . . .
Review: (Revised after reviewer took course in etiquette). "Mesoscale Meteorological Modeling" is the new second edition of the flagship text in the field. It is reasonably priced and seems to be well organized, addressing a lot of important problems. Aside from the discussion of thermodynamics, Professor Pielke's book is lucid and coherent.

To make a more specific criticism, consider section 2.2,entitled "Conservation of Heat." For a start I might complain that heat is not something conserved in atmospheric processes. In the usual thermodynamic usage, heat means energy transferred through thermal processes, is not an exact differential, and is not conserved. I think he means conservation of energy, but why not say so? It gets worse before it gets better. To quote from the first paragraph: "The first law of thermodynamics for the atmosphere states that differential changes in heat content, dQ, are equal to the sum of the work performed by an object, dW, and differential changes in internal energy, dI."

The first law of thermodynamics is universal - applying equally to steam engines (in which context it was first identified) and black holes. The phrase "differential changes in heat content" is nonsensical, since heat is energy transferred, not "contained" energy. The word differential is not only vague but also unnecessary. It would have been more accurate to say that the heat transferred into a system is equal to the sum of the work performed by the system and the increase in the internal energy of the system.

On page 8, he says that the virtual temperature is less than or equal to the sensible temperature, but the opposite is in fact true. On the same page, I found his attempt to discuss perfect differentials confused and confusing. There is both a mathematical and a physical point involved here. The (thermodynamically interesting) perfect differentials are the total differentials of state variables. dQ is not such an exact differential, and that is why it is meaningless to talk about conservation of heat.

Another unfortunate line is "Internal forces are required to account for the dissipation of momentum by molecular motions." (page 16). This is misleading. Momentum is conserved - absolutely - and unlike energy is not usually converted ("dissipated") to a more inconspicuous form, like internal energy. The atmosphere can transfer momentum to other parts of itself, by pressure or friction, to the ocean or the solid Earth (again by friction) or even (in microscopic amounts, by tidal forces) to the sun and moon, but these should be considered external forces. I infer from the succeeding sentences that conversion of energy from one form to another was the point.

I could quibble about the fact that he confuses centripetal and centrifugal acceleration (page 14) or the fact that he for some obscure reason refers to conservation of momentum as "Conservation of Motion," but that might be excessively picky.

Despite this type of flaw, I think the book is potentially useful. Perhaps one should just skip the thermodynamics (and read about it some good elementary physics book, like Sears) and just read the part he apparently cares about - the modeling. Apparently this is as good as it gets on the subject of mesoscale modeling. In any case, I don't begrudge the money I spent on it - I learned some useful things about modeling coordinates in Chapter 6.

Rating:
Summary: Yes, but . . .
Review: (Revised after reviewer took course in etiquette). "Mesoscale Meteorological Modeling" is the new second edition of the flagship text in the field. It is reasonably priced and seems to be well organized, addressing a lot of important problems. Aside from the discussion of thermodynamics, Professor Pielke's book is lucid and coherent.

To make a more specific criticism, consider section 2.2,entitled "Conservation of Heat." For a start I might complain that heat is not something conserved in atmospheric processes. In the usual thermodynamic usage, heat means energy transferred through thermal processes, is not an exact differential, and is not conserved. I think he means conservation of energy, but why not say so? It gets worse before it gets better. To quote from the first paragraph: "The first law of thermodynamics for the atmosphere states that differential changes in heat content, dQ, are equal to the sum of the work performed by an object, dW, and differential changes in internal energy, dI."

The first law of thermodynamics is universal - applying equally to steam engines (in which context it was first identified) and black holes. The phrase "differential changes in heat content" is nonsensical, since heat is energy transferred, not "contained" energy. The word differential is not only vague but also unnecessary. It would have been more accurate to say that the heat transferred into a system is equal to the sum of the work performed by the system and the increase in the internal energy of the system.

On page 8, he says that the virtual temperature is less than or equal to the sensible temperature, but the opposite is in fact true. On the same page, I found his attempt to discuss perfect differentials confused and confusing. There is both a mathematical and a physical point involved here. The (thermodynamically interesting) perfect differentials are the total differentials of state variables. dQ is not such an exact differential, and that is why it is meaningless to talk about conservation of heat.

Another unfortunate line is "Internal forces are required to account for the dissipation of momentum by molecular motions." (page 16). This is misleading. Momentum is conserved - absolutely - and unlike energy is not usually converted ("dissipated") to a more inconspicuous form, like internal energy. The atmosphere can transfer momentum to other parts of itself, by pressure or friction, to the ocean or the solid Earth (again by friction) or even (in microscopic amounts, by tidal forces) to the sun and moon, but these should be considered external forces. I infer from the succeeding sentences that conversion of energy from one form to another was the point.

I could quibble about the fact that he confuses centripetal and centrifugal acceleration (page 14) or the fact that he for some obscure reason refers to conservation of momentum as "Conservation of Motion," but that might be excessively picky.

Despite this type of flaw, I think the book is potentially useful. Perhaps one should just skip the thermodynamics (and read about it some good elementary physics book, like Sears) and just read the part he apparently cares about - the modeling. Apparently this is as good as it gets on the subject of mesoscale modeling. In any case, I don't begrudge the money I spent on it - I learned some useful things about modeling coordinates in Chapter 6.

Rating:
Summary: Author Discussion
Review: I read the Reviewer's comments and appreciate his overall positive review. However, I feel it is necessary to clarify misconceptions regarding the basic physics material which is presented in the review.
The conservation equations that are presented do not mean a quantity such as heat is always conserved. As discussed in the text, there are sources and sinks of heat in the conservation of equation of heat that is presented. A conservation equation for motion is also just as appropriate as writing a conservation equation for momentum. We can write a conservation equation for any quantity, such as a trace gas (e.g. CO2). Source/sink terms can be accounted for in this mathematical framework.
The equations in the book are specifically written for the atmosphere, which is treated as an ideal gas. This is why the qualification is added in the text that the equations are for the atmosphere (and specifically the earth's atmosphere). The equations developed in the book from the first principle of thermodynamics are only appropriate for the earth's atmosphere, since the ideal gas equation for air is used.
The basic phyics text in Chapters 2 and 3 have been extensively reviewed by numerous students and others and has been found to be solidly based in fundamental concepts. The Reviewer did correctly find a typo in that the virtual temperature is greater than the actual temperature whenever water vapor is present. The inequality on page 8 was reversed but the text and the explanation in that paragraph are correct and should be clear to a reader.
Finally, I thank the reviewer for taking the time to complete the review. If there is a third Edition, I certainly will acknowledge that review.