3-33. What determines frontal classification? 1. Density differences 2. Temperature differences 3. Frontal movement 4. Involved air masses 3-34. What  classification  is  given  to  the  front  that separates  a  warm  air  mass  from  a  retreating mass of cold air? 1. Warm 2. Cold 3. Quasi-stationary 4. Occluded 3-35. What   are   the   primary   frontal   zones   in   the Northern Hemisphere? 1. Polar and tropical 2. Polar and arctic 3. Arctic and tropical 4. Polar and equatorial 3-36. Cold air being heavier than warm air will either underrun the warm air or be overrun by warm air. 1. True 2. False 3-37. Which  of  the  following  statements  refer(s)  to frontal slope? 1. A front’s position along the Earth’s surface 2. The   zone   of   discontinuity   between   air masses 3. The ratio of a frontal surface’s elevation to horizontal extent 4. All of the above 3-38. Which of the following statements concerning the  relationship  between  fronts  and  cyclones (low-pressure centers) is correct? 1. All surface fronts develop a closed cyclonic circulation at the surface and aloft 2. Upper-level   cyclones   that   lower   to   the Earth’s surface always contain fronts 3. Every  front  is  associated  with  a  cyclone and travels with it 4. Fronts  can  occur  anywhere  but  cyclones cannot 3-39. What  is  the  average  speed  of  wave  cyclones along the polar front? 1. 10 - 15 knots 2. 15 - 20 knots 3. 20 - 25 knots 4. 25 - 30 knots 3-40. When is a frontal wave most intense? 1. When a cyclonic circulation develops 2. When  a  cyclonic  circulation  causes  the cold air to overtake the warm air and forms an occlusion 3. When  the  pressure  in  the  wave  cyclone begins to lower 4. When  the  pressure  in  the  wave  cyclone reaches its lowest point 3-41. When two air masses having different densities are  brought  together  by  the  prevailing  wind field, what takes place? 1. A front forms 2. There’s   a   decrease   in   the   temperature grient 3. The windflow parallels the isotherms 4. Each of the above 3-42. What is cross-isothermal flow? 1. The flow of wind across isobars 2. The flow of wind across isotherms 3. The flow of wind across fronts 4. A col. 3-43. Frontogenesis  is  most  likely  to  occur  where there  is  a  concentration  of  isotherms  and  a circulation that sustains the concentration. 1. True 2. False 3-44. Which of the following statements concerning frontolytical processes is correct? 1. They are most effective in the lower layers of the atmosphere 2. They are more common than frontogenetical processes 3. They bring about frontal dissipation 4. Each of the above 16