Saturday, August 13, 2011


There have been quite a few heatbursts in Oklahoma this year, and one occurred last night here in Norman. What is so fascinating about these heatbursts are the variety of signatures they produce ranging from 10 to 180 minutes of strong temperature rises and dew point falls, to weak temperature rises and strong dew point falls, gusty winds, and strong pressure falls.
Note the two heat bursts from Norman between 4 and 5 am having increased the temperature by 10F from 70 to 80 over that 45 minute span. Notice how long the episode is but how sharp those peak temperatures are. I also found it interesting that the pressure drop was 4 hPa with wind gusts to 30 mph just preceding the first burst, but a lack of gusty winds on the higher temperature heatburst with a pressure rise.

I was curious if the NSSL-WRF had a similar feature but I could not zoom into the old forecast graphic to see anything so sharp in the temperature field, but there were strong dew point drops for a similar area. This suggests that this event had some predictability. Further analysis awaits.

Much credit is due to the Oklahoma Mesonet for collecting this data, and the citizens of Oklahoma for supporting such science activities.

Friday, August 12, 2011


The last few days have seen what I hope to be the start of a drought buster the drought get busted here in Central OK and it started off with the transition to Northwesterly flow aloft. Convection developed up in Kansas and produced outflow which propagated south and resulted in the production of a bore which transitioned to a series of solitons. The latter are atmospheric gravity waves (amplitude ordered) which propagate on the interface of the inversion aloft. You can see the waves on radar (below).
What I find interesting is that these waves passed over the Oklahoma mesonet and were well resolved with the 5 minute interval data collection. As the waves approached Norman there were 3 or 4, and passing through Norman there were 5, and afterward possibly a sixth wave.

The following day we had two waves which may be another set of bores. These waves contributed to the development of convection in eastern OK which gave the area some much needed rainfall and kept temperatures down for the whole day.

On the 10th, the radar depiction above, the NSSL WRF model did a good job depicting the convection and outflow, but I doubt there was a bore as it might not be well resolved spatially on a 4km grid. One thing I know that will be beneficial in model development is to output time series so we can see what kind of waves (density currents, gravity waves, bores, solitons, etc) emanate from model generated convection. In this way we can test whether the models are capable of simulating these features. This will probably be more valuable at finer resolution as has been shown in research grade real-data simulations down into the sub 1km grid spacing range.

These waves can be implicated in all kinds of processes, from pre-conditioning the environment to being the cause of convection initiation, to doing nothing. Exploring these fine scale features and quantifying their impacts on the model simulations (through physics sensitivity) is just another way to help understand the fine resolution models (and maybe contribute to our understanding of the real world).

Tuesday, August 9, 2011

Skipping class

There was an interesting blog entry over at Freakonomics concerning "how professors should incentivize classroom attendance". There is a good example which I won't repeat because it only fit economics classes. I do want to address the questions they posed.

1. Is the student a consumer?
Yes, the student is a consumer of knowledge. The basic assumption is that the professor serves as both a translator of the textbook from a set of facts into useable knowledge and someone who applies that knowledge. Now not all classes allow themselves to be taught like this. In almost all classes there is some foundation upon which all subsequent learning is built. An Intro class though probably has more foundation than students care to master.

The student is not a consumer of grades. Grades are not something to be mastered, the material is. Oftentimes the true meaning of what you have learned takes additional perspective, additional time, and application to find its use and/or value. At the time it may seem like a neat trick. Later it may become something you use often and becomes second nature. The pythagorean theorem comes to mind.

Making class about reaching some set number of points becomes more about the points than actually achieving learning. I have seen it before in a class I TA'ed. A student did all the extra credit. He did well on his tests. He did most of the homework. He filled in "A" for all 50 questions on the last exam, saying he needed only 20 points to get an A. It was difficult to know if this student had learned anything or just did the work he was supposed to do. It was at this point that extra credit was not on my good side as a reward system.

2. Does classroom attendance equate to learning?
I used to think that Yes was the correct answer. The number of learning styles in the classroom has increased dramatically. So to reach larger audiences with different learning styles with one professor is difficult. It is not impossible, unless the student views him/herself as a consumer. But lets assume (in my ideal fantasy) that this is not the case. The best professor's can bring the material to life if it is bland. They can also add perspective, nuance, and practicality that can make the material more interesting. They can also be lively, interesting, humorous, engaging, and approachable. In this way the classroom experience can be mined by each student for that which captures their imagination.

But nothing a professor can do will ever change the motivation, attitude, and expectations of the student. These are simply not in the professors agenda for lecture everyday. But they go a log way to make learning possible or at least make the knowledge accessible.

So I think that classroom attendance is a necessary first step in achieving motivation and allowing an interaction to develop between the professor and students. The interplay that develops is thus a function (nonlinear) of the student and professor relationship inside the classroom. If that relationship goes stagnant for whatever reason it is the students responsibility to improve it. There is time available for this type of activity: Office Hours.

I once begged my students that were struggling to show up. They did and we worked on learning. It may not be classroom time but it served the same purpose: face to face contact. Did it work for everyone? No of course not. See the student responsibilities I listed above.

3. Are students a fair market to judge professors?
Once the class is over and they have perspective on the material and the relevance to their life or career, then yes. Immediately after they took the class? Not so much. See student responsibilities. It isn't a one way process, this learning thing. It is two ways. If you go in expecting me to to feed your brain, and your brain simply remembers it, then you missed the point and need to click "Next Blog" at the top of the page.  I even demonstrated this in class once.

I got a silver platter. I gave a student all my knowledge (which easily fit on this platter). I asked if the mere act of giving them knowledge worked at helping them learn. It was rhetorical. I can stand there and talk. for. ever. and. ever. Will they just suddenly get it by showing up?

I found out that students in that class didn't like to read the book.

4. Do bonus/penalty systems work?
No. See the extra credit assignment I discussed above. But when I started taking them to task on the book they at least opened it, flipped through it. Which I wanted. I incentivized the book and thus learning. I asked what the chapter was about. It wasn't a hard question, but how many missed it the first time? Quite a few. I kept them on their toes with simplicity. Note that I did not incentivize the grades. I got them to commit to act. Or not.

Really in the end a bonus or penalty system only works if they CARE. You cannot make a student care about learning if they walk in not CARING. The best professors care about learning. They don't care about grades, or points, or even exam scores. They use exams as a metric to monitor learning. If you cheat, the professor gets the sense that you are learning. How can we help you learn if we already think you are learning. That is the students penalty and the rationale for the honor system.

The only system that works for getting students to learn are the burden of responsibilities that students place on themselves. We talk alot about personal responsibility. But when you start buying stuff and want your money's worth, logic goes out the window, and it is about someone else's responsibility to fulfill a deal. Bonus and penalty systems make the system seem leveraged (in your favor ... a discount) when they are not. By that I mean bonus points are a plus for you in the absolute sense. Penalties are a bonus for you if you bet your classmates will be penalized more than you and thus are relative. Both can be advantages to your grade but not your learning.