2-44. Most  high-level  jet  operational problems are created by what type of  cirriform  clouds? 1. Cirrouncinus 2. Cirrocumulus 3. Cirrostratus 4. Cirrus (proper) 2-45. In the upper troposphere, what is the result of the slow ascent of air  that  has  insufficient  freezing nuclei in the higher levels? 1. The formation of cirrus haze 2. The  formation  of  cirrocumulus clouds 3. The  formation  of  cirrostratus clouds 4. The formation of “anvil” cirrus clouds 2-46. Assume that an aircraft is to fly through thin cirrus clouds in which the temperature is -35°C and the dewpoint is -37°C. What aircraft visibility  should  be  forecasted? 1. 1 mile 2. 2  miles 3. 3  miles 4. 7  miles 2-47. A ridge line is approaching your station. You  should  forecast extensive  cirrostratus  clouds  to occur at what period? 1. Before arrival of the 500-hPa ridge line 2. After passage of the 500-hPa ridge line 3. Before arrival of the surface ridge line 4. After passage of the surface ridge line 2-48. The mean height of the bases of cirriform clouds are greater at the equator than in the mid-latitudes. 1. True 2. False 2-49. Where are the densest and most extensive  cirrus  clouds  found relative to the jet stream? 2-50. The correct prediction of rain versus snow at a location depends mostly upon which of the following factors? 1. The height of the cloud bases 2. The temperature at the surface 3. The height of the freezing level 4. The temperature at the base of the cloud 2-51. In most precipitation situations, warming in the lower troposphere is generally  expected  to  accompany  the precipitation due to which of the following  movements? 1. Strong warm air advection and upward  vertical  motion 2. Strong  warm  air  advection  and downward  vertical  motion 3. Cold air advection and strong upward  vertical  motion 4. Cold air advection and strong downward  vertical  motion 2-52. What is the primary cause of the lowering of the “bright band” within the first 1 1/2 hours after the  onset  of  precipitation? 1. Vertical  motion 2. Horizontal   advection 3. Evaporational   cooling 4. Combined effects of all of the above 2-53. A rain-snow zone is most closely tied to which of the following factors? 1. The position of the warm front 2. The position of the polar front 3. The direction of the surface winds 4. The track of the surface disturbance 2-54. Which of the following local thermal parameters used in a snow versus rain forecast is the LEAST reliable when considered by itself? 1. Stratum  thickness 2. Surface  temperature 3. Upper  level  temperature 4. Freezing level height 1. Below the jet stream axis 2. Above the jet stream axis 3. Poleward of the jet stream axis 4. Equatorward of the jet stream axis 14