Geography 1700 Supplement to Quiz #3 Extra-tropical and/or mid-latitude storms such as the November 2013 typhoon Haiyan This PowerPoint is not a substitute for reading the textbook and taking good notes in class.

For Quiz #3 I have seen a creative variety of responses to the essay option. The version I used most often in class is simplified compared to the book, and compared to the version shown here. Some students choose the book version; other students choose the version I put on the dry erase board. Both work very well. Compare the version in this PowerPoint to the brief version I will put in the “Quiz #3 Answers” document to be posted on on Wednesday, November 13.

Jet Streams Meridional vs Zonal Flow When the jet stream provokes storms by mixing cool/dry with warm/wet storminess can occur. Mid-latitude storms often begin with mixing of cool/dry air and warm/wet air as the jet stream(s) undulates more north/south, helping to mix differing air masses. High Low

Notice that is eastward-moving storm is typical - counter-clockwise air in the mid-latitudes

Frontal Weather This one is a cold front. A warm front would have similar features, but more gradual. In any case, consider the steps of storm development I list in the “Quiz #3 Answers” I will post on Nov 13.

Notice that the cold- front side is more vigorous than the warm front side (right side).

Life of a Midlatitude Cyclone Notice that the cold front side shows more severe radar returns – more vigorous lifting and more likely severe weather. Relatively Cold Air Relatively Warm Air

Notice that in a mid- latitude cyclone, cold and warm air don’t mix at first. As Coriolis force helps turn the air, mixing begins as warm, humid air lifts over cooler, drier air that is more heavy. Rising air provokes condensation, precipitation and strong winds. At the end, warm air is temporarily stable above cold air below Westerly winds

Warm, wet air rises above cool/dry air classic “frontal” storm. Here we see how the jet stream (with storm track) helps pull low and high pressure cells toward each other. The difference between warm/wet and cool/dry helps produce rising air, high wind, precipitation, hail, lightning.

If you click quickly on the next six slides you can see how a mid-latitude cyclone can develop.

Figure 9.18a

Figure 9.18b

Figure 9.18c

Figure 9.18d

Figure 9.18e

Figure 9.18f