Department of Earth & Climate Sciences Name______San Francisco State University Spring 2020

ERTH 260 Quiz #5 400 pts Due by 11:59 PM Thursday May 21, 2020 Answer in spaces provided or on separate sheets if there is not enough space.

A. General Circulation Features. (50 pts)

Figure 1 shows the model of General Circulation of earth’s atmosphere we’ve been discussing in some of the Content Presentations.

Figure 1: Model of General Circulation of Earth’s Atmosphere.

1. Provide the names of the circulation cells encompassing the latitudes shown by the brackets at locations A, B, and C:

Location A (Two possible names, give either) ______(3 pts)

Location B ______(3 pts)

Location C ______(3 pts)

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2. Indicate which of the features shown in the box below (by number) are found at the locations in Fig. 1 given below the box. There can be more than one at any of the locations.

i. Subtropical Jet ii. Polar High iii. Intertropical Convergence Zone iv. Equatorial Low v. Horse Latitudes vi. Dry Line vii. Ozone Layer viii. Doldrums ix. Subtropical Highs x. Outflow Boundary xi. Polar Jet xii. Polar Front

Insert numbers of ALL of the choices above into the line next to the Location (below) in Fig. 1. There can be multiple features at the locations indicated and not all the choices above are conceivable at the locations shown. (3 pts each correct choice; total of 27 points)

Location D ______

Location E ______

Location F ______

Location G ______

Location H ______

Location I ______

3. At which location would the Rossby Number have the highest value. Explain. (14 pts)

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B. Waves in the Jet Stream (150 pts)

Figure 2 gives the 500 mb analysis for 12 UTC 5 May 2020. The axes of troughs at this level are shown at A, B, C, and D.

Fig. 2: 500 mb Analysis for 12 UTC 5 May 2020

1. Which of the trough axes shows the probable position of a Long Wave trough? Explain. (25 pts) 2. We have discussed how the Rossby Number expresses the relative strength of the Coriolis Acceleration in determining the nature of the flow. How does the information on this map indicate that the Rossby Number must be extremely small at the range of latitudes shown. (30 pts) 3. The Rossby Wave Speed Equation was discussed in one of the Content Presentations and is

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Where c is the phase speed of the wave (the speed of the trough, in this case), u is the jet stream speed along a line of latitude and the term to the far right is viewed as a correction factor that at a given latitude is directly proportional to wavelength. You can assume that the jet stream speed averages out to around 50 knots on this diagram.

Using the concept (no calculations) embodied in this equation, explain why Trough A shown in Fig. 2 will be moving faster than Trough B. (25 pts)

4. The horizontal divergence found east of upper air trough axes can be estimated by this expression, discussed in one of the Content Presentations.

Based on the concept (no calculations) of this equation, which of the troughs shown in Fig. 2 would have the least horizontal divergence associated with it. Explain. (You can assume that the amplitude of the troughs shown in Figure are roughly the same.) (25 pts)

5. Figures 3 and 4 are average 500 mb charts for one month. We have discussed the relationship of the strength of the jet stream and the number of waves that appear within it to seasonal considerations.

One of these figures shows the pattern for May. Discuss which one and the reasons you chose it based upon the strength of the jet stream and the number of waves. (45 pts)

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Figure 3: Average 500 mb chart for some month in the winter or the spring.

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Figure 4: Average 500 mb chart for some month in the winter or the spring.

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C. Sounding and Hodograph Interpretation (100 pts)

The sounding and hodograph for a location near Salina, KS on May 28, 2019 is given in Figure 5. Tornado picture was shot near Luray KS, about 60 miles west of Salina KS at around 6PM CDT.

Figure 5: Sounding and hodograph for a location near Salina KS at 7PM CDT 28 May 2019.

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Figure 6: Tornado near Luray KS (60 miles west of Salina) at approximately 6PM CDT 28 May 2019 (picture by John Monteverdi)

1. Examine the sounding and the following in the table below the sounding: CAPE/CIN for surface parcel lift (SFC), Convective Temperature, and Maximum Temperature. Discuss how these indicate that thunderstorms were likely to form or be in progress at the time of the sounding. (25 pts) 2. Examine the following in the table below the sounding/hodograph: STP, SRH for 0-1 km and 0-3 km layers, SFC-6km shear. a. STP and SRH are abbreviations. Expand them out. (15 pts) b. Describe which of these values indicates that the supercell cascade was likely to go to completion. Explain, making sure you mention what that last step is. (25 pts) c. Describe which of these values indicates that the updraft was likely to be long- lived. Explain. (25 pts) 3. Describe how the tornado form/shape shown in Fig. 6 would be characterized. (Presentation on Tornado Shapes) (10 pts)

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D. Climate Change. (50 pts)

The expectation of meteorologists and climate scientists is that the equator-pole temperature gradient will weaken during the 21st century due to the way this current anthropogenic warming is manifesting, namely, more warming in the polar regions than in the tropics.

1. Given what we have discussed about the pattern and movement of waves in the middle and upper troposphere, explain why this would mean that the midwinter flow at jet stream level would be characterized by more meanders than we typically experienced in the 20th century. (25 pts) 2. Discuss why the context established in question (1) just above is consistent that California is likely to experience swings from very wet years to very dry years during the 21st century. (25 pts)

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