Geophysical Fluid Dynamics (Meteo 520)
Project Two: Vorticity Generation and Tornadogenesis
new The first discussion class is on Wednesday, 14 November 2001. Please bring your write-up to the start of class.

In this project we apply knowledge of the vorticity equation to the question of tornadogenesis. You will be given an article from the journal Nature that looks at long term variations in tornado numbers and poses a reason for the changes that depends on vorticity. This article elicited many interested responses. Based on your understanding of vorticity, you will be asked to assess both the original article and the published responses to this article.

The article this project centered on is:

Isaacs et al. (1975): "Effect of vorticity pollution by motor vehicles on tornadoes." Nature, 253, 254-255.

Another article by Morton (1984) covers many basic examples of vorticity generation and diffusion, from a classical fluid dynamics perspective. While this may not seem too much like "real meteorology", these examples form the building blocks of the types of flows we observe and forecast in the real atmosphere and so can be extremely useful tools. I recommend that you use this article as background for your thinking about the project:

Morton, B. R., 1984: "The generation and decay of vorticity". Geophys. Astrophys. Fluid Dyn., 28, 277-308.

PROJECT 2, Part A: Individual Written Critiques of Isaacs et al. (1975)

On the day of our first class discussion (scheduled for Wednesday, 14 November 2001), each person will arrive with a written evaluation of both the article and the responses completed. This only needs to be one to two pages, but must be completed on time. You will hand these to me as you enter the room.

PROJECT 2, Part B: Group Discussion and Consensus Paper

I will assign you each to a discussion group when you arrive in class on Wednesday, 14 November 2001. In your groups (of 3-5 people) you will discuss the article and responses. You will form a group position. Each member of the group will write a summary of the group position and any points on which they dissent from the group (with justification) by the next discussion class.

It is quite possible that your group won't come to full agreement on this topic in the single class period provided. In order to complete this project properly, you will probably want to schedule some more discussion time out of class.

PROJECT 2, Part C: Open Class Discussion

When you arrive at the second discussion class (scheduled for Monday, 26 November 2001), you will hand me your second piece of written work, describing your group's position and your own additional ideas. You must all be ready to defend these ideas. This will be a general class discussion, but I will call on individuals (hiding won't help!).

Recommended Approach to Project Two

Essentially, approach this as if you were going to be publically reviewed by an audience of your peers (or, at least, folks more scary than we can drum up here at Penn State). This means that you have to:

(1) Be very attentive to the facts. You should specifically cite literature (probably class notes or textbooks) to dispute the arguments presented in the paper and comments;
(2) Be constructively critical of the arguments presented. Resort to the equations (!), scaling arguments, etc.;
(3) Think carefully about what you have learned about vorticity and apply it!;
(4) Think carefully about what you know about cars and trucks and apply it;
(5) Evaluate the quality of the responding letters.
(6) Refrain from writing disparagingly about the authors. In a public debate it is not fair game to deride the authors. This is a battle of the minds and if the authors' arguments are weak, you should be able to highlight the intellectual weaknesses.

As professional meteorologists, you will be expected to communicate information about the weather and climate constantly, and to a wide variety of people. Therefore, I will give no allowance for sloppy writing. I expect professional efforts here.

Summary of Deadlines:

  • Paper A due and first group discussion for Project 2 Wednesday, 14 November 2001
  • Paper B due and second class discussion on Monday, 26 November 2001

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