The exam will include true false, multiple choice, fill-in-the-blank, and short answer sections, just like exam 1 but without the cloud identification. The following is a list of what I want you to get out of the chapters. Disclaimer: There is likely to be some material on the exam that we discussed or that was part of your homework that is not explicitly in this list, although in my mind the list covers that information. I believe that if you understand the material below, you should be in very good shape, but if you think there is a question on the exam that was not part of the study guide, that will not be sufficient to make me feel it was an unfair question. I consider the following to be fair game: anything I explained in a lecture, anything that was on the homework, anything that is on any of the active learning exercises that we did, and anything below. Plus you should know and understand one "weather proverb" that I used to start a lecture.
There is no single explanation of global circulation in the text, but we spent a fair amount of time on it in class. Understand how the sun and Coriolis Force combine to produce this circulation, prevailing winds, and so on. Terms to know: Hadley Cell, Ferrel Cell, Polar Cell, Polar front, prevailing easterlies, prevailing westerlies.
Chapter 6: Forces and Force Balances. You should know and understand the basic forces that affect weather: pressure gradient, Coriolis, friction, and gravity. PG: how does a change in pressure lead to wind? Coriolis: why do things in the Northern Hemisphere deviate to the right, how does Coriolis vary with latitude (you have to know that 0 degrees latitude is at the equator and 90 degrees is at either pole), and understand the four points on p. 107 that you had to list in your homework. Friction: how does friction affect geostrophic winds, where is it strongest, how does it change as we rise through the atmosphere, what affects friction. Gravity: gravity allows for hydrostatic balance (p. 108) in the atmosphere. How do these interact? Understand the idea of balance between forces. How do Coriolis and PG combine to produce geostrophic or near geostrophic winds? How does the Polar Front and geostrophic balance combine to produce the Jet Stream? For this, you will need to understand geostrophic winds, and the idea that warm air takes up more volume than cold air, so in the upper atmosphere you will find dramatic pressure differences if temperatures at the surface and up are dramatically different. Terms to know: Pressure-gradient force, Coriolis "force", hydrostatic balance, geostrophic balance, geostrophic wind, jetstream.
Chapter 7: The Development of High- and Low-Pressure Systems. You need to understand convergence and divergence. What gives rise to convergence or divergence aloft (changes in wind speed, curvature, jetstreaks) or at the surface (uneven surface heating, changes in friction, pressure differences). For this, you need to be aware that surface pressure is only a function of the amount of air in the column above a given point. More air above means more pressure because there is more weight above you; less air means lower pressure. How is wind speed affected by whether air is moving counter-clockwise or clockwise, and how does this affect surface pressure system formation in the vicinity of curved flow (such as a trough over the Rocky Mountain area)? In a typical trough, be able to pinpoint where you would expect convergence and divergence aloft, and High and Low pressure at the surface, based upon the curvature effect. We won't worry so much about the jetstreak effect, but you should be aware that it exists. Understand heating and cooling effects: heating of an air column makes it take up more room, which leads to higher pressure aloft (because there is a "hill" of air above the warm air region), which leads the air to kind of "spill" over into surrounding regions (until it reaches geostrophic balance), which leads to low pressure at the surface. This also leads to rising air in a low and sinking air in a high (understand figure 7.8), and you need to know how this affects weather (cloudy in low pressure systems, clear in highs). Latent heating can drive this type of change--understand how cloud formation in Low Pressure systems can feed into the strengthening of the low. Similarly, understand how high pressure systems build on themselves in the winter through radiant cooling. Where do you expect to see strong Highs in the summer and winter? Be able to reason through why air rotates clockwise around a high and counterclockwise around a low. Terms to know: Convergence, divergence, pressure ridge, pressure trough, jetstreaks, friction layer.
Chapter 8: Air Masses and Fronts. Understand airmasses, why they form, where they come from, and how do they affect weather in the US? What is a cold, warm, and occluded front? How is it shaped, why is it shaped this way, and how does that affect the expected weather and cloud type? How quickly do warm and cold fronts move (mostly with respect to each other)? What is a dryline? Why do they tend to produce strong thunderstorms, and why would the moist air rise up over the dry air (as opposed to vice-versa)? What is the symbol for a cold front, warm front, occluded front, stationary front, and dryline? Be able to look at a map of station data (temps, winds, and so on) and figure out where the low pressure system is, and where cold and warm fronts are. Terms to know: Extra-tropical cyclone, cold front, warm front, dryline, occluded front, stationary front, cold occlusion, warm occlusion, maritime polar, maritime tropical, continental polar, continental tropical, continental arctic.
Chapter 9: Extratropical Cyclones Forming East of the Rocky Mountains. These are the weather systems that generally affect us here in Iowa. You will definitely need to have a conceptual model of a "typical" extra-tropical cyclone. This model should include: where and why do you expect to see warm fronts, cold fronts, and drylines or occluded fronts if they occur; how do these systems develop. How does air move around a typical cyclone (see figure 9.4). How do we expect winds to change when a front moves through? Precipitation? Temps? Humidity? What causes storms to intensify and then weaken? Terms to know: None.
Chapter 10: Extratropical Cyclones Forming Along the East and Gulf Coasts. This chapter is really about nor'easters. Understand how they move from the Gulf to the East Coast, and what causes them to intensify. Understand why they tend to be more intense than Rocky Mountain cyclones (see the list on pages 172-173). How does the passage of a previous cyclone lead to conditions which allow these systems to form? How does the air/land boundary drive the intensification of these systems? Understand how cold air damming and cold air trapping influence the type of weather coming from these storms and their intensity. Why do the two jetstreams often merge in the vicinity of such a storm? You should be aware of the two major storm tracks, but don't need to be able to differentiate them in detail. Terms to know: Polar jetstream, subtropical jetstream, cold air damming, cold air trapping,
Chapter 11: Freezing Precipitation and Ice Storms. Understand the concept of supercooling, and how this relates to freezing precipitation. What type of vertical structure in the atmosphere gives rise to different types of precipitation. You must understand and be able to reproduce the major concepts in Figure 11.1. Where does freezing rain usually fall with respect to a typical front. What is freezing drizzle, and how does it differ from freezing rain? How does cold air damming influence freezing rain? Very roughly, how is freezing precipitation distributed around the US? Understanding this will probably help you to understand freezing precipitation. What are the major dangers from freezing precip? Terms to know: Supercooling, freezing rain, sleet (ice pellets), freezing drizzle.