DEPARTMENT OF GEOSCIENCES NAME ______
SAN FRANCISCO STATE UNIVERSITY November 29, 2012
Metr 356.01
Examination #2 Key
Fall 2012
200 pts
Part 1. Use and Interpretation of Weather maps
Figure 1 is the 300 mb chart for 12 UTC 9 November 2011. Note Lines A, B, C , D, and E and also note the Locations a, b, c, d, and e.
1. On Fig. 1, a ridge is at Line(s)
a. B and E (both)
b. A and C (both)
c. C
d. D
e. A
2. On Fig. 1, a trough is at Line(s)
a. A and E (both)
b. D and E (both)
c. C
d. D
e. B
3. On Fig. 1, divergence is probably occurring at Location
a. a
b. b
c. c
d. d
e. e
4. On the basis of your interpretation of Fig. 1, the divergence pattern that we would expect with such a pattern in the upper troposphere (as discussed in class) would predict that a surface dynamic low pressure area should be found under Location
a. a
b. b
c. c
d. d
e. e
Figure 2 is the surface chart for 12 UTC 9 November 2011. Note the pressure systems at A and B and the frontal lines at locations a, b and c.
5. On Fig. 2, the pressure system at A is
a. a warm core low
b. a dynamic low
c. a dynamic high
d. a wave cyclone
e. b. and d.
6. On Fig. 2, Line a is a(n)
a. Occluded Front
b. Stationary Front
c. Cold Front
d. Warm Front
e. Dry Line
7. On Fig. 2, Line b is probably a
a. Occluded Front
b. Stationary Front
c. Cold Front
d. Warm Front
e. Dry Line
8. On Fig. 2, Line c is probably a
a. Occluded Front
b. Stationary Front
c. Cold Front
d. Warm Front
e. Dry Line
9. On Fig. 2, the pressure system at B is a
a. a warm core low
b. a dynamic low
c. a dynamic high
d. a wave cyclone
e. b. and d.
10. On Fig. 2, the pressure at Salt Lake City, UT (just to the south of the pressure system labeled B) is
a. 933.8 mb
b. 33.8 C
c. 1333.8 mb
d. 1033.8 mb
e. 937.3 mb
Figure 3 is the Meteogram for Saint Louis, 2000 UTC 8 to 2000 UTC 9 November 2011.
11. The direct evidence (seen on the meteogram given in Fig. 3) of a frontal passage at Saint Louis is
a. the wind shift between 8 UTC and 9 UTC.
b. the lowest pressure that occurred around 8 to 9 UTC.
c. the rainfall that occurred between 9 UTC and 14 UTC
d. a., b., and c. above.
e. sharp temperature drop between 9 UTC and 14 UTC
12. The indirect evidence (seen on the meteogram given in Fig. 3) of a frontal passage at Saint Louis is
a. the wind shift between 8 UTC and 9 UTC.
b. the lowest pressure that occurred around 8 to 9 UTC.
c. the rainfall that occurred between 9 UTC and 14 UTC
d. a., b., and c. above.
e. sharp temperature drop between 9 UTC and 14 UTC
13. The evidence (seen on the meteogram given in Fig. 3) suggests that the front passing Saint Louis was
a. a cold front.
b. a warm front.
c. a stationary front.
d. an occluded front.
e. no front passed Saint Louis.
Part II. Statistical Measures Important in Characterizing the Climate of an Area
14. The term “normal” (in the context of “normal” rainfall or “normal” temperature) is
a. the usual rainfall or temperature expected in an area.
b. defined as the average rainfall or temperature for the whole period of record.
c. defined as the mean for the 30 yr period ending in the last year of the last decade
(currently1981-2010)
d. a measure of correlation.
e. the standard deviation expressed as a percentage.
15. Correlation measures the degree to which
a. the given relationship between the events is not due to chance alone and there is a systematic
reason for the relationship.
b. the average rainfall or temperature for the whole period of record does not change.
c. the mean for the 30 yr period ending in the last year of the last decade (currently 1981-
2010) reflects the long term mean.
d. the occurrence of one event is linked, by statistical test to the occurrence of another event.
e. the standard deviation is expressed as a percentage.
16. Which of the following measures the range (either as a number or a ratio) of precipitation values
relative to the average that can be expected 67% of “the time” (meaning, 67% of the years in the long term record will have rainfall values within the range)
a. standard deviation
b. correlation coefficient.
c. coefficient of variation
d. extreme values.
e. (a) and (c) above.
17. The 22 year drought cycle is a dominant feature evident in the precipitation record (five year running means) of Los Angeles.
a. T
b. F
18. In the context of correlation, the given relationship between the events is not due to chance alone and there is a systematic reason for the relationship is the definition for
a. average or mean value.
b. correlation coefficient.
c. coefficient of variation
d. statistical significance
e. standard deviation
Part III. California Rainfall Variability
Refer to Figure 4, a diagram that shows the seasonal rainfall for the period for the period of record for Downtown San Francisco. Questions 19-24 refer to this chart.
19. The present location for the rain observation for Downtown San Francisco is
a. San Francisco State University
b. Old US Mint off of Duboce
c. City Hall
d. Ferry Building
e. Coit Tower
20. The mean seasonal rainfall for Downtown San Francisco is approximately
a. 44 inches
b. 34 inches
c. 24 inches
d. 14 inches
e. 154 inches
21. The term seasonal rainfall implies
a. that the rainfall shown is only for the winter season.
b. that the rainfall shown is only for the summer season.
c. that the rainfall shown comes seasonally.
d. that the rainfall shown is calculated for the period July 1 of one year to June 30 of the next.
e. that the rainfall shown is calculated only for the winter season.
22. The dashed red lines shown on the chart encompass approximately
a. 67% of the seasonal rainfall totals.
b. the extreme values.
c. the wettest year.
d. the driest year.
e. the correlation coefficient.
23. The coefficient of variation shown on the chart was obtained by
a. subtracting the standard deviation from 100.
b. dividing the temperature by the dew point temperature.
c. comparing San Francisco’s rainfall with that of New York
d. multiplying the correlation coefficient with the rainfall.
e. dividing the standard deviation by the mean seasonal rainfall.
24. Two stations report the same average annual rainfall. One station reports a coefficient of variation
of 50% and the other a coefficient of variation of 20%. The station with the higher coefficient of
variation
a. has more than 67% of its yearly rainfall totals either greater or lesser than one standard deviation
and,therefore has higher rainfall variability.
b. has annual rainfall totals that depart more greatly from the average value and, therefore
has higher rainfall variability.
c. has lower rainfall variability.
d. has higher areal variabilty of rainfall.
e. has a lower standard deviation of rainfall.
Fig. 5a shows the 30 year running mean of seasonal rainfall for downtown San Francisco. Questions 25 to 27 refer to this chart.
25. The 30 year running mean smooths out the season-to-season rainfall variations so that longer term shifts in climate can be deduced.
a. T
b. F
26. The information shown on Fig. 5a suggests that
a. rainfall variability was great in the mid 20th century.
b. the standard deviation of rainfall was great in the 20th century.
c. the late 19th century was relatively dry.
d. the 20th century was relatively dry.
e. the climate is getting drier currently.
27. One way of interpreting the graph given in Fig. 5a is that it shows the variation in the “normal” rainfall over the period shown.
a. T
b. F
Fig. 5b is a chart that shows the coefficient of variation for the 30 year running means given in the previous figure. Questions 28 and 29 refer to this chart.
28. The first value plotted on Fig. 5b for the 30 years ending in 1878-79 is 0.38. This means that
a. 67% of the seasonal values during that 30 year period varied plus or minus 38% from the long term average.
b. 33% of the seasonal values during that 30 year period varied plus or minus 38% from the long term average.
c. the standard deviation was 0.38”
d. the long term average was accurate only 38% of the time.
e. the seasonal rainfall was highly reliable 38% of the time.
29. An examination of Figs. 5a and 5b together suggests that in recent years (compared to the mi 20th
century)
a. the seasonal rainfall has increased and that the average value of rainfall has become a more reliable indicator of the rainfall that might occur in any given year.
b. precipitation has decreased and so too has the rainfall variability.
c. the rainfall variability has increased but that the mean seasonal rainfall has decreased.
d. the seasonal rainfall has increased, but that the average value of rainfall has become a less reliable indicator of the rainfall that might occur in any given year.
e. the tendency for extreme values to occur has decreased.
Part IV. Summer and Fall Patterns
Figure 6 shows the mean July surface (1000 mb) temperature for the period 1971-2000. Questions 30 to 33 refer to this chart.
30. If there were no other factors that would influence pressure patterns, Fig. 6 suggests that, at the
SURFACE
a. there would be a low pressure area at A and B.
b. there would be a low pressure area at A.
c. there would be a high pressure area at B.
d. there would be a low pressure area at B.
e. there would be a high pressure area at A and B.
31. If there were no other factors that would influence pressure patterns, Fig. 6 suggests that ALOFT
a. there would be a low pressure area at A and B.
b. there would be a high pressure area at A.
c. there would be a high pressure area at B.
d. there would be a low pressure area at B.
e. there would be a high pressure area at A and B.
32. The area of maximum surface heating seen in Figure 6 is not in the geometric center of the North
American continent because
a. of the influence of the mountains isolating the Great Basin/Southwest US from the moderating influences of the oceans.
b. of upwelling.
c. of the Gulf Stream.
d. of the California Current.
e. b. and d. above are correct.
33. The colder temperatures (relative to those on the continent at a given latitude) are more extreme
along the West Coast because
a. of the influence of the mountains isolating the Great Basin/Southwest US from the moderating influences of the oceans.
b. of upwelling.
c. of the Gulf Stream.
d. of the California Current.
e. b. and d. above are correct.
Figure 7a and 7b give the 500 mb and surface weather charts, respectively, for 12UTC 22 October 2000. Questions 34 to 41 relate to these figures.
34. Fig. 7a and 7b could be used to illustrate
a. the weather pattern associated with advection fog.
b. the weather pattern associated with summer thunderstorms.
c. the weather pattern associated with tule fog.
d. the weather pattern associated with snow.
e. the weather pattern associated with Diablo winds.
35. What is your best estimate for surface wind direction at San Francisco on this day (from Fig. 7b)?
a. southwest wind.
b. northeast wind.
c. northwest wind.
d. southeast wind.
e. south wind.
36. What is your best estimate for wind direction at 18000 feet over San Francisco on this day (from Fig. 7a)?
a. southwest wind.
b. northeast wind.
c. northwest wind.
d. southeast wind.
e. south wind.
37. The high pressure area on Fig. 7b over the Pacific Northwest and northern Great Basin is
a. a thermal high.
b. a dynamic low.
c. a wave cyclone.
d. a dynamic high.
e. North American Thermal Low.
38. Diablo Winds are examples of a general class of winds called
a. foehn winds.
b. chinook winds.
c. Santa Ana winds.
d. gust front winds.
a. upslope winds.
39. Diablo winds are hot because they sink from high elevation to low elevation, warming compressionally, and because
a. they are hot to begin with, originating over the Great Basin in the warm season.
b. they come from the warm tropics.
c. they are associated with a warm front.
d. they are associated with low dew point temperatures.
e. they come from the Gulf of Mexico.
40. Diablo winds are associated with low relative humidity because they are associated with high
temperatures and low dew point temperatures to begin with and because, as they sink to sealevel, the difference between the temperature and dew point gets even larger.