An interview with Prof. Roland Stull, the author of

Practical Meteorology: An Algebra-based Survey of Atmospheric Science

20 February 2018.  Updated Nov 2019.  Vancouver, Canada.

Roland Stull

Q. Why provide the book for free?

Stull:  Many reasons.  Primarily, I wanted to share my passion for meteorology with as many readers as possible.

Q. Why do you use pressure units of kPa and not hPa?
Stull:  I did it for the students.  We instructors should teach to the students' future, not to our past.  I learned millibars (mb) when I was a student.  Millibars were in my past.  It seems to me that hPa is a deception to make mb look as if it is a SI unit.

Q. But Thompson & Taylor's 2008 "Guide for the Use of the International System of Units (SI)" NIST p811 lists hecto and deka as acceptable prefixes in their section 4.3.  And WMO also allows hPa.
Stull:  True.  And in that same NIST publication, section 7.9 on Choosing SI prefixes: the authors state that "It is often recommended ... that only prefix symbols that represent the number 10 raised to a power that is a multiple of 3 should be used".  (e.g., ... nano, micro, milli, kilo, mega, giga, ...)
Q.  You must have been convinced of using kPa early in your career, because your 1988 "Intro to Boundary-Layer Meteorology" book also uses kPa.
Stull:  True.  SI recommendations were adopted by physicists and engineers many decades ago - - we in atmospheric science are still catching up.  In my books, I am trying to help new students get started on a good path. 

Q. Why do you use M for wind speed, instead of V ?
Stull: Because U and V already denote the x- and y-components of wind.  Although experts can usually figure out how to interpret V from the context, it is not as obvious to novices.  Think of M as Magnitude of the wind.  (Or in kinematic units, it represents a Mass flux.)

Q. Why limit the book to algebra and trig?
Stull:  To make quantitative aspects of meteorology accessible to more students, during earlier years in their university experience.

Q. But don't you miss a lot by not showing the derivations?
Stull:  True.  But the vast majority of meteorologists never use differential equations or do calculus derivations in their career.  The exception is grad students.  See my 3-slide presentation for pros and cons of an algebra-based university curriculum. 

Q. What university level did you write the book for?
Stull:  All university levels, including grad school.  I cover the basics, and I cover fairly advanced concepts in some of the chapters. But the advanced concepts are accessible to all students having a background in algebra and trig.

Q. Why cover so many topics in in the book?
Stull:  Curiosity.  It gave me an opportunity to learn new stuff.  Plus I have a bad memory.  So by writing it after I learned it, I could always access it later after I forgot it.

Q. Aren't you worried that the book is too long?
Stull:  In electronic form, the length is irrelevant.  Teachers and students can pick whichever subset of chapters is useful for their course, and can ignore the rest.

Q. How do you accommodate readers with color blindness?
Stull:  Over 98% of the color textbook figures are identical to black & white figures in Meteorology for Scientists and Engineers, 3rd Edition (MSE3), 2011.  For MSE3, I had manually changed the colors to grey shading in a sensible way (e.g., stronger was darker grey, weaker was lighter grey).  All readers can access the black & white figures from MSE3 online at .

Q. Why is your Atmospheric Boundary Layer chapter so short?
Stull:  Because more details are in my other book "An Introduction to Boundary Layer Meteorology".

Q. Why do you call it Atmospheric Boundary Layer (ABL) instead of Planetary Boundary Layer (PBL)?
Stull:  Because my boundary-layer (BL) chapter covers only the atmospheric BL, not other planetary BLs such as ocean BLs or the magnetospheric BL.

Q. In the surface heat budget section of the boundary layer chapter, your signs for the upward and downward heat and radiation fluxes seem different than what is in most of the literature. 
Stull:  True.  I had initially followed the sign convention used by most surface-budget experts.  But when I tried to merge that section with the rest of the book, the signs disagreed.  Namely, everywhere else in the book (and in meteorology in general) upward fluxes are defined as positive and downward fluxes are negative. 

Q. For atmospheric soundings, you plot 3 points to represent a single air-parcel state, while most people use only 2 points.  Why? 
Stull:  People who plot 2 points are actually implicitly plotting 3 points.  Experienced meteorologists can find the "hidden" 3rd point from context (total water is hidden under Td for unsaturated air, but Td is hidden under T for saturated air).  Novices can learn the concepts more quickly if they explicitly see all 3 points.

Q. I've never seen the "apex" method for determining parcel static stability.  Why do you make it so complicated?  Isn't it easier just to use the lapse rate?
Stull:  Lapse rate is inadequate to determine if the air will become turbulent.  The reason is that buoyant air parcels can move finite vertical distances and can cross into regions of subadiabatic lapse rate.  If you make the mistake of assuming a well-mixed layer is neutrally stratified, then you will conclude the wrong turbulence characteristics that cause you to compute incorrect smoke-plume dispersion -- a mistake that could be expensive to your clients.  The "apex" method is a quick way to determine nonlocal static stability from plotted soundings.

Q. You take an unusual approach in the General Circulation chapter.  Why?

Stull: I struggled with this chapter, because most of the general circulation books that I found were out of date. They didn't agree with modern global NWP re-analysis data.  I relied heavily on the re-analysis data, which showed large differences in Hadley-cell magnitude and jet-stream characteristics between winter and summer hemispheres.  The net result is sketched in Fig. 11.58.

Q. There are so many symbols for variables in this book that it is confusing.  Also, some symbols are re-used to represent different things.
Stull:  A new "Appendix C • Notation" was created in summer 2018. You can access it now from the home page. It will be added to the "whole book" pdf and to printed copies of the book in a future edition.

Q. Will you provide an answer key or solution manual to the homework exercises?
Stull:  No. Sorry.  Once the answers escape into the wild (i.e., internet), then the questions they answered lose their value.  But almost every "Apply" exercise has a corresponding Sample Application in the body of the chapter.

Q. Why is the index so long?
Stull:  One purpose of the book is as a reference, for which an index is important.  While you don't need an index to electronically search the book pdf file for key words, you do need an index to find concepts associated with words that are NOT in the book.  Example: twister.  It took me a month to create the index by hand.

Q. Why do you identify the book with a "version" number rather than an "edition" number?
Stull:  Versions 1.00 through 1.02b are all slight variations of the "first edition".  By "slight", I mean that almost any topic can be found on the same page number of all versions.  The index points to the same pages in all versions.  But each version has its own isbn, as was requested by librarians and bookstores.

Q. I found concepts and equations in the book that I hadn't seen before.
Stull:  True. I am a research scientist who enjoys creating new theories.  In many sections of the book there were concepts that could be well illustrated with simple theories or toy models. I had fun trying to devise these models.

Q. Can you give some examples?
See the list of new theories and models.

Q. But some of those examples are similar to ones already published by others.
Stull:  True.  But then I would have missed the challenge of trying to devise them myself.  I learn stuff better when I try to explain things myself.

Q. How often will you revise the book?
Stull:  About every two or three years. Inbetween those revisions, please use the errata.  I am still an active full professor at UBC (see my CV), so I have many other duties (teaching, research, service) in addition to textbook writing.

Q. How much money do you earn for the various versions of this book?
Stull:  Zero income.  No royalties from all forms of this book, including printed versions.  No advertising revenue.

Q. Do you know how many people use the book?
Stull:  I use a web analytics program to monitor downloads from this web site. Between 5 March 2016 and 15 Nov 2019, there were 29,225 users from 160 countries (4,033 cities) worldwide who did 108,292 downloads of pdf files of individual chapters or of the whole book.  I thank all of you for telling your friends about this book.
Last updated Nov 2019 by R. Stull