First, an important reminder: I think that a lot of people have forgotten that the outlines for the lectures are posted online and also on the course CD. For each lecture, you can click on "Calendar/Outlines" and get a set of figures and a basic outline of the material. These aren't "the notes", but they will be very helpful when you study.
Key terms
lapse rate, Dry Adiabatic Lapse Rate, Wet Adiabatic Lapse Rate, Environmental Lapse Rate, stability, absolutely stable, conditionally unstable, absolutely unstable, temperature inversion
air-mass thunderstorm, squall-line thunderstorm, supercell thunderstorm, mesoscale convective complex (MCC), moist tongue, cumulus stage, mature stage, dissipating stage, anvil, updraft, downdraft, overshooting top, mammatus clouds, capping inversion, gust front, entrainment
tornado, funnel cloud, wall cloud, hook echo, Fujita scale, tornado watch, tornado warning
hurricane, tropical cyclone, tropical storm, stadium effect, eye, eyewall, rainband, Saffir-Simpson scale, storm surge
lightning, thunder, Flash-to-Bang method, hail, microbursts, headwind, tailwind, step leader, streamer, charge separation, lightning rod
El Nino, La Nina, thermocline, trade winds, equatorial current, warm pool, cold tongue, Southern Oscillation Index
Key concepts
Stability is important on this exam, since the storms described in this section all require the air to be either conditionally unstable or absolutely unstable. The questions on the test are quite similar to the "extra questions" that I added to the homework--if you weren't able to answer those questions, get help now! To this end, know the following:
- Given the temperature at two levels of the atmosphere, be able to compute the Environmental Lapse Rate. Remember, the ELR is positive if temperature decreases as you go up in the atmosphere.
- Given an Environmental Lapse Rate, be able to state whether that layer of the atmosphere is absolutely stable, conditionally unstable, or absolutely unstable. Therefore, you are going to need to know those rules that compare the ELR to the MALR and the DALR in order to determine stability (for example, ELR < MALR means that the air is absolutely stable).
- Know what "absolutely stable", "conditionally unstable", and "absolutely unstable" mean with regard to whether or not an air parcel will rise. In particular, understand what the "conditional" in "conditionally unstable" is all about.
- Know when and where you are likely to find layers of the atmosphere that are absolutely unstable or absolutely stable.
In general, you need to know why thunderstorms happen when and where they do. For example, why are there so many thunderstorms in Florida? In Colorado? Where do thunderstorms happen with respect to midlatitude cyclones? (In the warm sector, but why?) Know about good things that support thunderstorm development, like moist tongues. Know about bad things that hinder thunderstorm development, like entrainment. Know why entrainment is bad for thunderstorm growth.
Know the life cycle of a typical air-mass thunderstorm: cumulus stage, mature stage, dissipating stage. Be able to describe the vertical motions and the precipitation associated with each of these stages. How long do thunderstorms like this last?
Know the basic structure of a thunderstorm: anvil, overshooting top, mammatus clouds, updraft, downdraft, gust front, etc. Figure 10-6 in your book would be a good place to start.
Know the differences between the four main types of thunderstorms: air-mass thunderstorms, squall-line thunderstorms, supercell thunderstorms, MCCs.
What are the differences between a "tornado watch" and a "tornado warning"? Know the basic statistics for tornadoes: how common are they, how big are they, how fast are their winds, what is the typical direction in which they move, etc. Know the "trends" for tornadoes: are more or fewer people dying of tornadoes now than in the past, are more or fewer tornadoes reported now than in the past, etc. Understand how we assess the strength of tornadoes using the Fujita scale.
Know the basics of hurricane structure. Understand that "typhoon" and "hurricane" are both just terms for "tropical cyclone"--the only difference is where they are occurring. Understand the naming system for tropical storms and hurricanes. Know the basic ingredients of the "hurricane cookbook"--in other words, what things do you need in order to form a hurricane?
Know the basic statistics for hurricanes: how many form per year in the Atlantic, which area of the world gets the most hurricanes, what time of year hurricanes form, etc. Understand how we assess the strength of hurricanes using the Saffir-Simpson scale. Know what "storm surge" is and why it is so destructive. Know the typical tracks of hurricanes in the Atlantic Ocean. Know why hurricanes die when they move over land.
Know the basics of the "weather hazards" we discussed in class: lightning, thunder, hail, and microbursts. Know which parts of a thunderstorm and its surrounding areas are positively and negatively charged. Understand how lightning causes thunder. Know the basic features of a cloud-to-ground lightning strike. Understand what determines the size of hailstones that reach the ground. Microbursts are an important topic because of their threat to aviation--understand what they are and how they affect aircraft that are approaching runways.
There are several questions on the exam about safety. Know about what to do when a tornado is in your area. Or a hurricane. Know how to protect yourself from being struck by lightning. Understand the Flash-to-Bang technique.
Know the basic statistics about El Nino. Understand the basic features of the General Circulation of the atmosphere and ocean during a NORMAL year, an EL NINO year, and a LA NINA year. Know some of the unusual weather features we find during an El Nino or a La Nina event.