Atpl 6 .txt

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Atpl 6 .txt
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  1. 6-001. What layer of the Earth's atmosphere lies above the Tropopause?
    6-001 (Answer). The STRATOSPHERE lies above the Tropopause. [Ref: ATP GSC s. 6.01]
  2. 6-002. What is the ISA standard lapse rate to the height of the tropopause?
    6-002 (Answer). The ISA standard temperature lapse rate is 1.98º C per 1, 000 feet to the height of the tropopause. [Ref: ATP GSC s. 6.01]
  3. 6-003. What is the ISA standard temperature from the tropopause upwards into the stratosphere?
    6-003 (Answer). The ISA standard temperature upwards from the tropopause is -56.5º C without change to the top of the stratosphere (ISA standard lapse rate of 1.98º C/1,000 feet no longer applies!). [Ref: ATP GSC s. 6.01]
  4. 6-004. What is the ISA standard height of the tropopause?
    6-004 (Answer). The ISA standard height of the tropopause is 36,000 feet. [Ref: ATP GSC s. 6.01]
  5. 6-005. Define the term "MSL Pressure".
    6-005 (Answer). MSL PRESSURE is station pressure reduced to mean sea level based on the average temperature over the last 12 hours. [Ref: ATP GSC s. 6.02]
  6. 6-006. What is the standard spacing of isobars on surface weather charts?
    6-006 (Answer). The standard spacing of isobars on surface weather charts is at 4 mb intervals. [Ref: ATP GSC s. 6.01]
  7. 6-007. What is the standard spacing of pressure contours on upper level weather charts?
    6-007 (Answer). The standard spacing of pressure contours on upper level weather charts is at 60 m intervals. [Ref: ATP GSC s. 6.01]
  8. 6-008. Where isobars are spaced closely on a surface weather chart, what does this indicate about the pressure gradient?
    6-008 (Answer). Where isobars are spaced closely on a surface weather chart, this indicates that there is a steep pressure gradient. [Ref: ATP GSC s. 6.01]
  9. 6-009. An aircraft is on an eastbound flight from Vancouver BC to Lethbridge AB maintaining a constant pressure level. The flight is experiencing drift to the south. What does this indicate in terms of the pressure systems affecting the flight?
    6-009 (Answer). Where an eastbound flight based on maintaining a constant pressure level experiences drift to the south, this indicates airflow coming from the north, and in terms of pressure systems, the aircraft will be either leaving a high or entering a low. [Ref: ATP GSC s. 6.01]
  10. 6-010. An aircraft is on an eastbound flight from Vancouver, BC to Winnipeg, MB. The aircraft maintains a constant pressure level. While enroute, the upper level winds are initially from the North, but change near the end of the flight to be from the South. Based on this information, what can be stated about the aircraft's true altitude?
    6-010 (Answer). Where an aircraft maintains a constant pressure level on an eastbound flight, where the winds are initially from the North, but change to be from the South, this indicates that the aircraft has entered a low initially, but when the winds are from the South, this indicates that the aircraft has left the low. Thus it can be said that the aircraft true altitude will have initially decreased ("from high to low, look out below!") and then increased as the aircraft left the low. [Ref: ATP GSC s. 5.01]
  11. 6-011. What influence does temperature have on the height of pressure levels?
    6-011 (Answer). Where temperatures are colder, pressure levels will be at lower heights that when temperatures are warmer. [Ref: ATP GSC s. 6.01]
  12. 6-012. Will the vertical distance between pressure levels be greater in warm air, or in cold air?
    6-012 (Answer). The vertical distance between pressure levels will be greater in warm air. [Ref: ATP GSC s. 6.01]
  13. 6-013. A large area to the southeast of a station has higher temperatures than to the northwest. Based on this information, where is the wind from?
    6-013 (Answer). Winds will be from the southwest. If the area to the southeast has higher temperatures, it will indicate a high to the southeast. Since a high pressure area will have winds that circulate clockwise, putting a high to the southeast of the station will yield winds that come from the southwest. Similarly, putting a low to the northwest of the station will yield winds from the southwest. [Ref: ATP GSC s. 6.01]
  14. 6-014. In terms of atmospheric pressure, when will a pressure sensitive altimeter indicate high if the correct altimeter setting has not been applied?
    6-014 (Answer). In terms of atmospheric pressure, where pressures are low, the pressure sensitive altimeter will indicate high if the correct altimeter setting has not been applied. [Ref: ATP GSC s. 5.02]
  15. 6-015. A aircraft is in level flight with an indicated altitude of 10,000 feet ASL on the pressure sensitive altimeter. The altimeter has been set to 29.52" Hg, however, the correct current altimeter setting is 29.92" Hg. Accordingly, what is the actual true altitude of the aircraft?
    6-015 (Answer). True altitude is 10,400 feet. To solve this problem, first, take the difference between current altimeter setting and indicated altimeter setting = 0.40" Hg = 400 feet. Since the aircraft is entering an area of higher pressure, the actual altitude is 400 feet + 10,000 feet = 10,400 feet ASL. [Ref: ATP GSC s. 6.02]
  16. 6-016. Two aircraft are both in the same general area of each other in level flight with 10,000 feet indicated altitude on their respective pressure sensitive altimeters. Aircraft A has an altimeter setting of 29.92" Hg, while Aircraft B has an altimeter setting of 29.42" Hg. Which aircraft will be at the higher true altitude?
    6-016 (Answer). Aircraft B, with the lower altimeter setting, will be at a true altitude of 400 feet higher than Aircraft A. Think of it this way: if you increase the read-out of the altimeter setting, you will also increase the corresponding height. Thus, for a constant height, increasing the altimeter setting will increase the indicated altitude, and you would have to lower your altitude to maintain the new height corresponding to the increased altimeter setting. [Ref: ATP GSC s. 6.02]
  17. 6-017. An aircraft has been cleared to conduct an approach for landing from FL 200. The current altimeter setting at the airport is 29.42" Hg, however, the pilot forgets to set the current altimeter for the approach and conducts the approach with 29.92" Hg set on the altimeter setting subscale. If we assume a non-precision approach MDA of 800 feet ASL, what will be the actual altitude of the aircraft at MDA?
    6-017 (Answer). Actual altitude will be 300 feet ASL. First convert difference between 29.92" Hg and 29.42" Hg into feet = 500 feet. Since current altimeter is LOWER than 29.92" Hg, aircraft will be 500 feet lower i.e. actual altitude for MDA 800 feet indicated will be 300 feet ASL. Think of "from high to low, look out below!". [Ref: ATP GSC s. 6.02]
  18. 6-018. In terms of atmospheric temperature, when will a pressure sensitive altimeter indicate high?
    6-018 (Answer). In terms of atmospheric temperature, where temperatures are much lower than standard, a pressure sensitive altimeter will indicate high. [Ref: ATP GSC s. 6.02]
  19. 6-019. Define the term "Altimeter Setting".
    6-019 (Answer). ALTIMETER SETTING is station pressure reduced to MSL under standard conditions. [Ref: ATP GSC s. 6.02]
  20. 6-020. What is the difference between an "Isothermal Layer" and an "Inversion"?
    6-020 (Answer). An ISOTHERMAL LAYER is when the temperature remains constant with an increase in height, while an INVERSION is when the temperature increases with an increase in height. [Ref: ATP GSC s. 6.03]
  21. 6-021. Based on adiabatic lapse rates, determine the height of the cloud base given a surface temperature of 15º C and dewpoint temperature of 3º C.
    6-021 (Answer). Cloud base will be at 4,000 feet AGL. Use Dry Adiabatic Lapse Rate of 3º C/1,000 feet. 15º - 3º = 12º drop in temperature at 3º/1,000 feet = 4,000 feet. [Ref: ATP GSC s. 6.04]
  22. 6-022. Assume a cloud is based at 3,000 feet AGL, where the temperature at this altitude is 3º C. Based on adiabatic lapse rates, at what height would the freezing level be found at?
    6-022 (Answer). The freezing level under these conditions would be found at 5,000 feet AGL. From the cloud base upwards, the air is saturated, therefore, we would use the Saturated Adiabatic Lapse Rate of 1.5º C/1,000 feet to find the height of the freezing level. Applying this lapse rate from the cloud base would require a drop in temperature of 3º to reach the freezing level, and 3º C/1.5º C per 1,000 feet = 2,000 feet. Adding 2,000 feet to 3,000 feet = 5,000 feet AGL freezing level. [Ref: ATP GSC s. 6.04]
  23. 6-023. Why does rising air cool less rapidly when it is saturated as compared to unsaturated air i.e. why is the Saturated Adiabatic Lapse Rate less than the Dry Adiabatic Lapse Rate?
    6-023 (Answer). Upon reaching saturation, condensation occurs, and there is a latent release of heat whenever water changes state from a vapour form to a liquid form. This latent heat release results in increasing corresponding lapse rate and thus the SALR will be less than the DALR. [Ref: ATP GSC s. 6.04]
  24. 6-024. Why does the air temperature drop when air is forced upwards?
    6-024 (Answer). When air is forced upwards, such as by terrain, orographic lift or movement of pressure systems and/or fronts, the air will expand and cool. This process is known as EXPANSIONAL COOLING. [Ref: ATP GSC s. 6.04]
  25. 6-025. What is the name of the lifting process that would produce cloud in mountainous areas?
    6-025 (Answer). OROGRAPHIC LIFT is the lifting process that would produce cloud in mountainous areas. [Ref: ATP GSC s. 6.04]
  26. 6-026. What happens to the relative humidity where air sinks, and what term is used to describe this sinking process?
    6-026 (Answer). SUBSIDENCE means sinking air, and where the air sinks, the pressure increases, the temperature increases, and the relative humidity decreases i.e. warmer air holds a greater amount of water vapour hence will have lower relative humidity. [Ref: ATP GSC s. 6.05]
  27. 6-027. What happens to the stability of air where there is heating from below?
    6-027 (Answer). Where there is heating from below, the air will become less stable. [Ref: ATP GSC s. 6.05]
  28. 6-028. What happens to the stability of air where there is cooling from below?
    6-028 (Answer). Where there is cooling from below, the air becomes more stable. [Ref: ATP GSC s. 6.05]
  29. 6-029. In general, in unstable air, are environmental lapse rates steeper or more shallow?
    6-029 (Answer). In general, environmental lapse rates will be steeper in unstable air. [Ref: ATP GSC s. 6.05]
  30. 6-030. In terms of stability, what is indicated by a parcel of air having an environmental lapse rate that is greater than both the DALR and SALR?
    6-030 (Answer). Air that has an environmental lapse rate that is greater than both the SALR and DALR will be unstable. [Ref: ATP GSC s. 6.04, 6.05]
  31. 6-031. What is the meaning of the term "Virga"?
    6-031 (Answer). VIRGA refers to precipitation that falls from below cumuloform type cloud that evaporates before it reaches the surface. [Ref: ATP GSC s. 6.06]
  32. 6-032. Mechanical turbulence, where present, is generally found at what range of heights?
    6-032 (Answer). Mechanical turbulence, where present, is generally found at heights of less than 3,000 feet AGL. [Ref: ATP GSC s. 6.07]
  33. 6-033. What classification of turbulence applies where there are large, abrupt changes in attitude or altitude, and the aircraft may be momentarily out of control?
    6-033 (Answer). Where turbulence causes large, abrupt changes in attitude or altitude, and the aircraft may be momentarily out of control, such turbulence will be classified as SEVERE TURBULENCE. [Ref: ATP GSC s. 6.07]
  34. 6-034. What is the name of the deflective force based on the Earth's rotation that causes highs to circulate clockwise in the northern hemisphere?
    6-034 (Answer). The CORIOLIS FORCE is the deflective force based on the Earth's rotation that causes highs to circulate clockwise in the northern hemisphere. [Ref: ATP GSC s. 6.08]
  35. 6-035. What is meant by the term "Diurnal Temperature Variation" and at what locations on the Earth will it be the greatest and least?
    6-035 (Answer). DIURNAL TEMPERATURE VARIATION refers to the variation of temperature between day and night. Diurnal temperature variation is greatest over the deserts and least over temperate oceans. [Ref: ATP GSC s. 6.08]
  36. 6-036. At approximately what height AGL will winds blow parallel to the isobars on a surface weather chart?
    6-036 (Answer). At approximately 3,000 feet AGL, winds will blow parallel to isobars depicted on a surface weather chart. [Ref: ATP GSC s. 6.08]
  37. 6-037. What will be the difference in direction and speed for winds at 3,000 feet AGL as compared to winds on the surface?
    6-037 (Answer). Due to the effects of surface friction, winds at the surface will tend to BACK (counter-clockwise change in direction) and DECREASE in speed as compared to winds at the 3,000 feet AGL level. [Ref: ATP GSC s. 6.08]
  38. 6-038. By what approximate angle will winds at the surface back as compared to the winds at 3,000 feet, assuming that the surface is rough land?
    6-038 (Answer). Winds over rough land will back about 30º as compared to winds at the 3,000 feet AGL level. [Ref: ATP GSC s. 6.08]
  39. 6-039. By what approximate angle will winds at the surface back as compared to the winds at 3,000 feet, assuming that the surface is water?
    6-039 (Answer). Winds over water will back much less than over water than land, generally from 0º - 15º as compared to winds at the 3,000 feet level. [Ref: ATP GSC s. 6.08]
  40. 6-040. What is the difference between a Sea Breeze and a Land Breeze?
    6-040 (Answer). A SEA BREEZE blows from the sea to the land by day, and is caused by the lower pressure area over the land as hot air moves up from the land, drawing in the air from the sea. A LAND BREEZE blows from the land to the sea by night, and is caused by the lower pressure area over the sea at night drawing in the colder air from the land. [Ref: ATP GSC s. 6.08]
  41. 6-041. What is the difference between a Katabatic wind and an Anabatic wind?
    6-041 (Answer). A KATABATIC WIND blows down valleys by night or ice-covered slopes, while an ANABATIC WIND blows up a slope or valley by day. [Ref: ATP GSC s. 6.08]
  42. 6-042. What atmospheric phenomenon is indicated by the presence of Lenticular or lens shaped cloud lying parallel to a mountain range?
    6-042 (Answer). LENTICULAR or lens shaped cloud lying parallel a mountain range is an indicator of MOUNTAIN WAVES and severe downdrafts. [Ref: ATP GSC s. 6.08]
  43. 6-043. Where mountain wave activity is present, what will be the effect on altimeter indications in the wave crests?
    6-043 (Answer). Where mountain wave activity is present, when in the wave crests, the altimeter will read high due to the low pressure created by the high winds. [Ref: ATP GSC s. 6.08]
  44. 6-044. During mountain wave activity, at what part of the mountain wave structure will the associated turbulence be greatest?
    6-044 (Answer). During mountain wave activity, associated turbulence will be greatest between the ground and the roll or rotor clouds. [Ref: ATP GSC s. 6.08]
  45. 6-045. What are the basic atmospheric properties for which air masses are classified?
    6-045 (Answer). Air masses are classified on the basis of their moisture and temperature in the horizontal. [Ref: ATP GSC s. 6.09]
  46. 6-046. What modification will take place to the Maritime Tropical air mass as it moves over the North Atlantic in summer?
    6-046 (Answer). As the Maritime Tropical air mass moves over the North Atlantic in summer, it is modified by passing over the cooler ocean surface to become Maritime Polar. [Ref: ATP GSC s. 6.09]
  47. 6-047. In winter, what are the three primary air masses that influence Canada's weather?
    6-047 (Answer). In winter, the three primary air masses that influence Canada's weather are the Maritime Polar, Maritime Arctic, and Continental Arctic air masses. [Ref: ATP GSC s. 6.09]
  48. 6-048. What is the order, from north to south, of the principal air masses that affect Canada's weather?
    6-048 (Answer). The order, from north to south, of the principal air masses that affect Canada's weather are the Continental Arctic, Maritime Arctic, Maritime Polar and Maritime Tropical air masses. [Ref: ATP GSC s. 6.09]
  49. 6-049. What is meant by the term "Polar Front"?
    6-049 (Answer). The term POLAR FRONT refers to the theoretical dividing line between the cold, polar dome of air over the upper part of the northern hemisphere at the point that this dome contacts the warmer, tropical air to the south. [Ref: ATP GSC s. 6.10]
  50. 6-050. Is frontal weather determined primarily by the moisture and stability of the warm air mass, or by the cold air mass in respect of a given front?
    6-050 (Answer). Frontal weather is determined primarily by the moisture content and stability of the warm air mass, in respect of a given frontal system, since it is the warm air mass that will be lifted. [Ref: ATP GSC s. 6.10]
  51. 6-051. Where a warm front yields showery precipitation, is the warm air mass in the front stable or unstable?
    6-051 (Answer). Where a warm front yields showery precipitation, this is an indication that the warm air mass in the front is unstable. [Ref: ATP GSC s. 6.10]
  52. 6-052. Where an aircraft encounters snow followed by ice pellets in winter, what form of precipitation can be expected to be encountered next?
    6-052 (Answer). Where an aircraft encounters snow followed by ice pellets in winter, freezing rain can be expected next, since ice pellets occur where there are warmer temperatures aloft while flying within colder air, and these conditions also produce freezing rain. [Ref: ATP GSC s. 6.10]
  53. 6-053. What is the direction of movement of a frontal wave?
    6-053 (Answer). A FRONTAL WAVE will move in a direction that is parallel to the isobars in the warm air sector. [Ref: ATP GSC . 6.10]
  54. 6-054. What is the direction of movement of winds at a stationary front?
    6-054 (Answer). Wind movement at a stationary front will be parallel to the front (not parallel to the isobars). [Ref: ATP GSC s. 6.10]
  55. 6-055. Describe the basic structure of an upper cold front.
    6-055 (Answer). An upper cold front involves a thin portion of the cold front being positioned far in advance of the main structure of the cold front. [Ref: ATP GSC s. 6.10]
  56. 6-056. With respect to an upper cold front, as the front approaches, will the frontal weather be experienced in advance of the temperature change, or before the temperature change?
    6-056 (Answer). Based on the fact that an upper cold front has a thin portion of the front that is advancing well ahead of the main body of the front, as the front arrives over a ground station, a temperature drop will be experienced first, followed later by weather as the main body of the upper front arrives above the station. [Ref: ATP GSC s. 6.10]
  57. 6-057. Describe the basic structure of an upper warm front.
    6-057 (Answer). An upper warm front is based on the main structure of the warm front being aloft, with an extended area of retreating cold air behind the frontal system. [Ref: ATP GSC s. 6.10]
  58. 6-058. With respect to an upper warm front, as the front approaches, will frontal weather be experienced in advance of the temperature change, or before the temperature change?
    6-058 (Answer). Based on the fact that an upper warm front has the main front ahead of the extended area of cold air, as the front arrives over a ground station, frontal weather will be encountered first followed later by a temperature drop when the end of the frontal system finally arrives. [Ref: ATP GSC s. 6.10]
  59. 6-059. What kind of cloud would be associated with a fast moving cold front where the warm air mass is moist and unstable?
    6-059 (Answer). A fast moving cold front that is uplifting a warm air mass that is moist and unstable will produce extensive unstable clouds of vertical development such as towering cumulus and cumulonimbus. [Ref: ATP GSC s. 6.10]
  60. 6-060. When passing through any frontal system, what change in wind direction can be expected?
    6-060 (Answer). When passing through any frontal system, a shift in winds to the right (clockwise change in direction) can be expected. [Ref: ATP GSC s. 6.10]
  61. 6-061. When flying in a cold air mass and then entering a TROWAL, what shift in temperature can be expected?
    6-061 (Answer). When flying in a cold air mass and entering a TROWAL (Trough of Warm Air Aloft), initially, the temperature will rise as the aircraft enters the warm air aloft, and, when leaving the warm air, the temperature will fall. [Ref: ATP GSC s. 6.10]
  62. 6-062. Refer to the complex low at Fig. 6-15. Based on the surface analysis chart, what air masses overlie YOW at 0600Z?
    6-062 (Answer). Based on the complex low at Fig. 6-15, there are two air masses that overlie YOW at 0600Z: the lower is mA, and above this in the TROWAL is mP. [Ref: ATP GSC s. 6.11]
  63. 6-063. Refer to the complex low illustration below. Make a sketch that would show a cross section of the air masses based on a line drawn from point A to B.
    6-063 (Answer). Below is a cross section that shows the air masses illustrated based on a cross section from point A to B. [Ref: ATP GSC s. 6.11]
  64. 6-064. Is the height of the tropopause higher over the equator, or over the poles?
    6-064 (Answer). The height of the tropopause is higher over the equator than over the poles. [Ref: ATP GSC s. 6.12]
  65. 6-065. Is the tropopause colder over the Equator or over the poles?
    6-065 (Answer). The tropopause is colder over the Equator (since it is higher). [Ref: ATP GSC s. 6.12]
  66. 6-066. In relation to a given frontal system, where will the associated jet stream lie?
    6-066 (Answer). In relation to a given frontal system, the associated jet stream will lie in the upper levels of the warm side of the frontal system at about the height of the cold air tropopause. [Ref: ATP GSC s. 6.12]
  67. 6-067. In relation to a jet stream core, where are the areas of greatest turbulence located?
    6-067 (Answer). In relation to a jet stream core, the areas of greatest turbulence are located A) above the core in the sloping tropopause; B) in the front below the core, and C) on the low pressure side of the core. [Ref: ATP GSC s. 6.12]
  68. 6-068. If CAT is encountered while crossing a jet stream, and the OAT is rising, what is the fastest way to depart the CAT?
    6-068 (Answer). If CAT is encountered while crossing a jet stream, and the OAT is rising, the aircraft should climb to leave the CAT fastest. [Ref: ATP GSC s. 6.12]
  69. 6-069. What spacing of isotachs on the 250 mb upper air charts will indicate that wind shear associated with CAT is likely?
    6-069 (Answer). Wind shear associated with CAT is more likely where 30 kt isotachs are spaced closer than 90 NM on 250 mb upper air charts. [Ref: ATP GSC s. 6.12]
  70. 6-070. If CAT is encountered while flying in a direct tailwind or headwind, is it generally best to turn to the north or to the south to leave the CAT?
    6-070 (Answer). If CAT is encountered while flying in a direct tailwind or headwind, it is generally best to turn to the south to leave the CAT. [Ref: ATP GSC s. 6.12]
  71. 6-071. The "Polar Jet Stream" is associated with which air mass?
    6-071 (Answer). The POLAR JET STREAM is associated with the Maritime Polar air mass.
  72. 6-072. In which direction will jet streams move in winter, to the south, or to the north?
    6-072 (Answer). Jet streams will move to the south in winter. [Ref: ATP GSC s. 6.12]
  73. 6-073. Are jet streams stronger in summer or in winter?
    6-073 (Answer). Jet streams are stronger in winter than in summer. [Ref: ATP GSC s. 6.12]
  74. 6-074. What conditions in respect of temperature, rate of catch and size of super-cooled water droplets can cause clear ice to form on an aerofoil?
    6-074 (Answer). Clear ice forms where there are large supercooled water droplets having a high rate of catch, at temperatures just below freezing. [Ref: ATP GSC s. 6.13]
  75. 6-075. What conditions in respect of temperature, rate of catch and size of super-cooled water droplets leads to the formation of rime ice on an aircraft?
    6-075 (Answer). Rime ice forms where there are small, super-cooled water droplets with a low rate of catch at temperatures well below freezing. [Ref: ATP GSC s. 6.13]
  76. 6-076. With respect to conditions leading to the formation of airframe ice, within what type of clouds will there be large, supercooled water droplets, stratus, or cumulus type cloud?
    6-076 (Answer). Cumulus type cloud is more likely to contain large, super-cooled water droplets that can lead to the formation of airframe icing. [Ref: ATP GSC s. 6.13]
  77. 6-077. At what range of temperatures will airframe icing be most severe?
    6-077 (Answer). Airframe icing will be the most severe in temperatures from 0º C to -15º C. [Ref: ATP GSC s. 6.13]
  78. 6-078. Where an aircraft in flight encounters visible ice crystals, is the formation of airframe ice likely?
    6-078 (Answer). Where ice crystals become visible in the air, airframe icing is less likely because of a lack of super-cooled water droplets in liquid form to attach to the aircraft. [Ref: ATP GSC s. 6.13]
  79. 6-079. What is the relationship between the geometry of an aerofoil and its collection efficiency of airframe ice?
    6-079 (Answer). Collection efficiencies of airframe icing vary inversely with the geometry of the collecting surface: i.e. thin leading edges, antennae masts etc. will have greater collection efficiencies than would canopies, thick wings or other rounded surfaces. [Ref: ATP GSC s. 6.13]
  80. 6-080. As rime ice accumulates on an aerofoil surface, does it tend to move forward, or rearward?
    6-080 (Answer). As rime ice accumulates on an aerofoil surface, it tends to move forward. [Ref: ATP GSC s. 6.13]
  81. 6-081. As clear ice accumulates on an aerofoil surface, does it tend to move forward, or rearward?
    6-081 (Answer). As clear ice accumulates on an aerofoil surface, it tends to move rearward. [Ref: ATP GSC s. 6.13]
  82. 6-082. Where icing intensity is indicated as "Moderate", what does this classification describe?
    6-082 (Answer). Where icing intensity has been classified as MODERATE, this indicates that the rate of accretion could be potentially hazardous and the use of de-icing/anti-icing equipment is necessary. [Ref: ATP GSC s. 6.13]
  83. 6-083. Due to the aerodynamic heating effects caused by compressibility of air at high speeds, above what speed will airframe ice never form?
    6-083 (Answer). Due to the effects of aerodynamic heating cause by compressibility of air, at speeds above about 500 kts airframe icing will not occur, regardless of weather conditions. [Ref: ATP GSC s. 6.13]
  84. 6-084. What happens to an aircraft's stall speed as airframe ice accumulates on an aerofoil?
    6-084 (Answer). As airframe ice accumulates on an aerofoil, the aircraft stall speed will increase. [Ref: ATP GSC s. 6.13]
  85. 6-085. What are the basic requirements for the development of a thunderstorm?
    6-085 (Answer). The basic requirements for the development of a thunderstorm are an adequate supply of moisture, an unstable air mass and a lifting agent. [Ref: ATP GSC s. 6.14]
  86. 6-086. What key event defines the onset of the Mature Stage of a thunderstorm?
    6-086 (Answer). The key event that defines the onset of the Mature Stage of a thunderstorm is the onset of precipitation. [Ref: ATP GSC s. 6.14]
  87. 6-087. What causes the formation of an "anvil" shape at the top of a thunderstorm in its mature stage?
    6-087 (Answer). The anvil formation that appears at the top of a thunderstorm in its mature stage is caused by the strong upper winds at the tropopause. [Ref: ATP GSC s. 6.14]
  88. 6-088. In the mature stage of a thunderstorm, what is the location of the "gust front"?
    6-088 (Answer). During the mature stage of a thunderstorm, as downdrafts hit the ground, a gust front is formed at the surface as this air drives forward. [Ref: ATP GSC s. 6.14]
  89. 6-089. In the mature stage of a thunderstorm, where may a "roll" cloud form?
    6-089 (Answer). During the mature stage of a thunderstorm, a ROLL cloud may form near the leading edge of the main cloud base in the shear area between the forward updraft and downdraft of the cell. [Ref: ATP GSC s. 6.14]
  90. 6-090. What is the dominant feature of the Dissipating Stage of a thunderstorm?
    6-090 (Answer). The dominant feature of the Dissipating Stage of a thunderstorm is a downdraft. [Ref: ATP GSC s. 6.14]
  91. 6-091. What is the name of a thunderstorm that has formed in a mountainous region?
    6-091 (Answer). A thunderstorm that has formed in a mountainous region is known as an Orographic thunderstorm. [Ref: ATP GSC s. 6.14]
  92. 6-092. At what range of temperatures are lightning strikes most likely in the mature stage of a thunderstorm?
    6-092 (Answer). Lightning strikes are most likely during the mature stage of a thunderstorm where temperatures are from -5º C to +5º C. [Ref: ATP GSC s. 6.14]
  93. 6-093. With respect to the rules for thunderstorm avoidance, one should avoid by at least what distance any thunderstorm identified as severe or giving an intense radar echo?
    6-093 (Answer). With respect to the rules for thunderstorm avoidance, one should avoid by at least 20 NM any thunderstorm identified as severe or giving an intense radar echo. [Ref: ATP GSC s. 6.14]
  94. 6-094. With respect to the rules for thunderstorm avoidance, a thunderstorm should be regarded as severe should it extend to what height?
    6-094 (Answer). According to the rules for thunderstorm avoidance, a thunderstorm should be regarded as severe should it extend to 35,000 feet or more. [Ref: ATP GSC s. 6.14]
  95. 6-095. With respect to the rules for penetration of a thunderstorm if unavoidable, at what penetration altitudes will critical icing areas be avoided?
    6-095 (Answer). With respect to the rules for penetration of a thunderstorm if unavoidable, to avoid the most critical icing, establish a penetration altitude below the freezing level or above the level of -25º C. [Ref: ATP GSC s. 6.14]
  96. 6-096. With respect to the rules for penetration of a thunderstorm, should the aircraft be flown at a constant altitude, or at a constant attitude?
    6-096 (Answer). With respect to the rules for penetration of a thunderstorm, the aircraft should be flown at a constant ATTITUDE so as to minimize the potential for structural damage, allowing the aircraft to "ride the waves". Flight at constant altitude will not be possible without causing the potential for structural damage. [Ref: ATP GSC s. 6.14]
  97. 6-097. With respect to the rules for penetration of a thunderstorm when unavoidable, what power settings should be used?
    6-097 (Answer). With respect to the rules for penetration of a thunderstorm when unavoidable, a power setting as appropriate for reduced turbulence penetration airspeed should be selected and maintained. [Ref: ATP GSC s. 6.14]
  98. 6-098. With respect to the rules for penetration of a thunderstorm, once a thunderstorm has been entered, should a straight course be maintained or should a 180º turn be executed to minimize the associated hazards?
    6-098 (Answer). According to the rules for penetration of a thunderstorm, once a thunderstorm has been entered, a straight course should be maintained (this will get the aircraft away from the hazards of the thunderstorm faster than by completing a 180º course reversal). [Ref: ATP GSC s. 6.14]
  99. 6-099. What is the approximate size of the horizontal extent of a microburst at the surface?
    6-099 (Answer). The approximate size of the horizontal extent of a microburst at the surface is from 2 - 2.5 NM. [Ref: ATP GSC s. 6.14]
  100. 6-100. What is the normal maximum time of duration of a typical microburst?
    6-100 (Answer). The normal maximum duration of a microburst life cycle is typically not more than 15 minutes. [Ref: ATP GSC s. 6.14]
  101. 6-101. Microbursts that contact the surface can yield horizontal winds gusting to what maximum speed?
    6-101 (Answer). Microbursts that contact the surface can yield horizontal winds that can gust to a maximum speed of 45 kts. [Ref: ATP GSC s. 6.14]
  102. 6-102. What are the basic requirements for the development of fog?
    6-102 (Answer). The basic requirements for the development of fog are a high relative humidity, a cooling process and condensation nuclei. [Ref: ATP GSC s. 6.16]
  103. 6-103. What are the requirements for radiation fog to occur?
    6-103 (Answer). Radiation fog typically occurs in high pressure systems where there is rapid cooling at night along with moist, humid air. A light breeze will also tend to increase the development and degree of radiation fog by creating a mixing action. [Ref: ATP GSC s. 6.16]
  104. 6-104. Will the presence of smoke or pollution increase or decrease the relative amount of radiation fog, all other factors being equal?
    6-104 (Answer). The presence of smoke or pollution will increase the amount of radiation fog, all other factors being equal, since there will be more condensation nuclei upon which water molecules can attach. [Ref: ATP GSC s. 6.16]
  105. 6-105. How is frontal fog produced?
    6-105 (Answer). Frontal fog is produced as precipitation from above in the warm air mass of the front saturates the cold air below. This saturation raises the dewpoint temperature, leading to fog at the frontal surface. [Ref: ATP GSC s. 6.16]
  106. 6-106. How is Arctic Sea Smoke produced?
    6-106 (Answer). Arctic Sea Smoke is a form of fog that is produced as cold arctic air moves over a large body of warm water. The colder arctic air will eventually raise the dewpoint temperature and wisps of fog resembling smoke in appearance will appear in the air above the water, hence the name "arctic sea smoke" used to describe this phenomenon. [Ref: ATP GSC s. 6.16]
  107. 6-107. By what process is "Ice Fog" produced?
    6-107 (Answer). Ice fog is produced via the process of SUBLIMATION, where water vapour in extremely cold air turns directly to ice crystals leading to ice fog. [Ref: ATP GSC s. 6.16]
  108. 6-108. What is the name of the service that provides in-flight weather information for long range flights enroute such as over the Atlantic ocean and high arctic over HF radio?
    6-108 (Answer). The VOLMET service is the name of the long distance aviation weather service provided over HF radio. [Ref: ATP GSC. 6.17]
  109. 6-109. Where can specific hours of operation and frequencies for VOLMET HF weather service be found?
    6-109 (Answer). Specific hours of operations and frequencies for VOLMET HF weather service can be found in the CFS. [Ref: ATP GSC s. 6.17]
  110. 6-110. What information is provided by a Graphic Area Forecast (GFA)?
    6-110 (Answer). The Graphic Area Forecast (GFA) provides, as a graphic display, the forecast weather under 24,000 feet ASL over a large geographical area. [Ref: ATP GSC s. 6.18]
  111. 6-111. What are the names of the 7 distinct GFA domains?
    6-111 (Answer). The names of the 7 distinct GFA Domains are as follows: PACIFIC, PRAIRIE, ONTARIO-QUEBEC, ATLANTIC, YUKON, NUNAVUT and ARCTIC. [Ref: ATP GSC s. 6.18]
  112. 6-112. How many times a day are GFA's issued?
    6-112 (Answer). GFA's are issued four times per day. [Ref: ATP GSC s. 6.18]
  113. 6-113. At what times are GFA's normally issued to be valid from?
    6-113 (Answer). GFA's are normally issued to be valid from 0000Z, 0600Z, 1200Z and 1800Z. [Ref: ATP GSC s. 6.18]
  114. 6-114. How are cloud heights indicated on a GFA, ASL or AGL?
    6-114 (Answer). Unless otherwise noted, cloud heights on a GFA are provided in feet ASL. [Ref: ATP GSC s. 6.18]
  115. 6-115. In the GFA, visibility is only provided when forecast to be less than how many miles?
    6-115 (Answer). In the GFA, visibility will only be displayed where it is forecast to be less than 6 SM. [Ref: ATP GSC s. 6.18]
  116. 6-116. On a GFA, what is the spacing between isobars?
    6-116 (Answer). On a GFA, isobars are spaced at 4 mb intervals. [Ref: ATP GSC s. 6.18]
  117. 6-117. In the GFA, are cloud heights provided for bases, for tops, or for both bases and tops?
    6-117 (Answer). In the GFA, cloud heights are provided for both cloud bases and for cloud tops. [Ref: ATP GSC s. 6.18]
  118. 6-118. In the GFA, in what colour are areas of precipitation indicated?
    6-118 (Answer). In the GFA, areas of precipitation are indicated in the colour GREEN. [Ref: ATP GSC s. 6.18]
  119. 6-119. In the GFA, how are areas of intermittent precipitation distinguished from areas of continuous precipitation?
    6-119 (Answer). In the GFA, areas of intermittent precipitation are indicated by green diagonal hatching, whereas areas of continuous precipitation are indicated by green shading. [Ref: ATP GSC s. 6.18]
  120. 6-120. How are areas of icing indicated on the GFA?
    6-120 (Answer). On the GFA, areas of forecast icing are indicated with BLUE DOTS. [Ref: ATP GSC s. 6.18]
  121. 6-121. How are areas of turbulence indicated on the GFA?
    6-121 (Answer). Areas of turbulence are indicated in RED on the GFA. [Ref: ATP GSC s. 6.18]
  122. 6-122. Where an outlook on a GFA is indicated as "VFR", what does this mean in terms of the forecast ceiling and visibility for the outlook period?
    6-122 (Answer). Where an outlook on a GFA is indicated as VFR, this indicates that the ceilings are forecast to be more than 3,000 feet, and visibilities are forecast to be greater than 5 SM during the outlook period. [Ref: ATP GSC s. 6.18]
  123. 6-123. Where an outlook on a GFA is indicated as "IFR", what does this mean in terms of the forecast ceiling and visibility during the outlook period?
    6-123 (Answer). Where an outlook on a GFA is indicated as IFR, this indicates that the ceilings are forecast to be less than 1,000 feet, and the visibilities are forecast to be less than 3 SM during the outlook period. [Ref: ATP GSC s. 6.18]
  124. 6-124. How are areas of cloud indicated on a GFA?
    6-124 (Answer). On a GFA, areas of cloud are depicted with scalloped edges that surround these areas. [Ref: ATP GSC s. 6.18]
  125. 6-125. On a GFA, when are surface winds indicated?
    6-125 (Answer). On a GFA, surface winds are only provided if expected to be greater than 20 kts sustained or gusts of 30 kts or more. [Ref: ATP GSC s. 6.18]
  126. 6-126. Refer to the Clouds and Weather GFA at Fig. 6-21. What is the speed and direction of movement of the low pressure system?
    6-126 (Answer). The speed and direction of movement of the low pressure system is 35 kts east. [Ref: ATP GSC s. 6.18]
  127. 6-127. Refer to the Icing, Turbulence and Freezing Level GFA at Fig. 6-21. What type and degree of icing has been forecast in the region marked "1", and for what range of heights is this icing forecasted?
    6-127 (Answer). At the region marked "1", localized severe clear icing has been forecasted from the surface to 3,000 feet ASL. [Ref: ATP GSC s. 6.18]
  128. 6-128. Refer to the following:

    TAF AMD CYHZ 110810Z 110806 14015KT P6SM 0VC030 TEMPO 0811 5SM TSRA BR OVC015
    FM1100Z 13015G25KT P6SM OVC030 TEMPO 1113 5SM -SHRA BR SCT008 OVC020 PROB30 1113 1SM TSRA BR OVC010
    FM1300Z 13015G25KT 1SM -RA BR BKN006 OVC015 PROB30 1303 1SM TSRA BR OVC006 BECMG 2123 17015KT
    FM0300Z 27012KT P6SM OVC015 RMK NXT FCST BY 09Z=

    What is the lowest ceiling forecast for the period from 1100Z to 1300Z?
    6-128 (Answer). The lowest ceiling forecast for the period from 1100Z - 1300Z is overcast at 1,000 feet AGL. [Ref: ATP GSC s. 6.19]
  129. 6-129. Refer to the following:

    TAF AMD CYHZ 110810Z 110806 14015KT P6SM 0VC030 TEMPO 0811 5SM TSRA BR OVC015
    FM1100Z 13015G25KT P6SM OVC030 TEMPO 1113 5SM -SHRA BR SCT008 OVC020 PROB30 1113 1SM TSRA BR OVC010
    FM1300Z 13015G25KT 1SM -RA BR BKN006 OVC015 PROB30 1303 1SM TSRA BR OVC006 BECMG 2123 17015KT
    FM0300Z 27012KT P6SM OVC015 RMK NXT FCST BY 09Z=

    What visibility has been forecast between 1300Z and 0300Z?
    6-129 (Answer). Between 1300Z and 0300Z, visibility is forecast to be 1 SM. [Ref: ATP GSC s. 6.19]
  130. 6-130. Refer to the following:

    TAF AMD CYHZ 110810Z 110806 14015KT P6SM 0VC030 TEMPO 0811 5SM TSRA BR OVC015
    FM1100Z 13015G25KT P6SM OVC030 TEMPO 1113 5SM -SHRA BR SCT008 OVC020 PROB30 1113 1SM TSRA BR OVC010
    FM1300Z 13015G25KT 1SM -RA BR BKN006 OVC015 PROB30 1303 1SM TSRA BR OVC006 BECMG 2123 17015KT
    FM0300Z 27012KT P6SM OVC015 RMK NXT FCST BY 09Z=

    What is the probability of a thunderstorm occurring at this airport during the period from 1300Z to 0300Z?
    6-130 (Answer). The probability of a thunderstorm occurring at this airport during the period from 1300 - 0300Z is 30 percent. This can be confirmed by the words "PROB30 1303 1SM TSRA ...". [Ref: ATP GSC s. 6.19]
  131. 6-131. Refer to the following:

    TAF CYQY 110540Z 110618 VRB03KT P6SM SCT100 FM1000Z 13010KT P6SM SCT008 OVC040 TEMPO 1018 P6SM -SHRA RMK NXT FCST BY 12Z=

    At what time will the next TAF be issued for this airport?
    6-131 (Answer). The next TAF for this airport will be issued at 1200Z. [Ref: ATP GSC s. 6.19]
  132. 6-132. Are winds in an Upper Level Winds and Temperatures Forecast (FD) provided in feet ASL or AGL?
    6-132 (Answer). Winds in an FD are provided in feet ASL. [Ref: ATP GSC s. 6.20]
  133. 6-133. What code is used on an upper level winds and temperatures forecast to indicate that winds are forecast to be "light and variable"?
    6-133 (Answer). The code 9900 is used to indicate forecast winds will be light and variable on an upper level winds and temperatures forecast. [Ref: ATP GSC s. 6.20]
  134. 6-134. Assume that the FD provides a code of "820742" for 39,000 feet. Based on this code, what is the forecast wind speed, wind direction and temperature?
    6-134 (Answer). Based on the code 820742, this indicates winds are from 320º True at 107 kts, temperature -42º C. For winds above 100 kts, 50 is added to the direction code, and the winds are assumed to be 100 kts plus the 2-digit winds indicated. [Ref: ATP GSC s. 6.20]
  135. 6-135. What kind of weather is described by a METAR?
    6-135 (Answer). METAR is the acronym for "Aviation Routine Weather Report" and it describes actual weather that was reported at a certain time for a given aerodrome. The weather described by a METAR includes basic observed weather, sky condition, visibility, temperature, dewpoint, altimeter setting and remarks. [Ref: ATP GSC s. 6.21]
  136. 6-136. What is the purpose of a "Special METAR", and when is it issued?
    6-136 (Answer). A SPECIAL METAR is issued when there has been a significant change to a previous regular METAR. Special METARs are issued whenever warranted. [Ref: ATP GSC s. 6.21]
  137. 6-137. In what fractional units are cloud layers reported in a METAR, and what is the name used to describe these fractional units?
    6-137 (Answer). In a METAR, cloud layers are reported in OKTAS, which are fractional units based on the number of EIGHTHS that the sky is covered by a particular cloud layer. [Ref: ATP GSC s. 6.21]
  138. 6-138. For the purposes of a METAR, what is a "ceiling"?
    6-138 (Answer). A CEILING, for the purposes of a METAR, is any time that there is a layer of cloud reported to be BROKEN (from 5 to less than 8 eighths cover) or OVERCAST (8 eighths cover). [Ref: ATP GSC s. 6.21]
  139. 6-139. In respect of a METAR, how would a ceiling made up of an obscuring condition on the surface such as fog be indicated?
    6-139 (Answer). In respect of a METAR, a ceiling made up of an obscuring condition on the surface such as fog would be indicated by the abbreviation "VV" followed by a three-digit number indicating the vertical visibility that can be seen when looking upwards into the layer. [Ref: ATP GSC s. 6.21]
  140. 6-140. Refer to the following:

    METAR CYQY 110700Z 17003KT 15SM BKN120 BKN160 01/M02 A3009 RMK AC5AC2 SLP191

    Of the two cloud layers that have been reported above CYQY, of what cloud type is each of these layers, and how much of each of these layers is visible from the ground?
    6-140 (Answer). The cloud layer at 12,000 feet is Altocumulus, and 5/8 of this layer is visible from the surface. The cloud layer at 16,000 feet is also Altocumulus, and 2/8 of this layer is visible from the surface. The amounts of each layer can be found at the end of the METAR by the code "AC5AC2", which indicates the amount and type of each successive layer as indicated in the sky condition of the METAR. [Ref: ATP GSC s. 6.21]
  141. 6-141. What is the purpose of a SIGMET?
    6-141 (Answer). A SIGMET is a serious weather condition that is reported as a warning to aircraft in flight. [Ref: ATP GSC s. 6.22]
  142. 6-142. Provide some examples of weather phenomena that would qualify for SIGMET warnings.
    6-142 (Answer). Examples of weather phenomena that would qualify for SIGMET warnings include active thunderstorms, squall lines, heavy hail, severe turbulence, heavy icing, mountain waves, hurricanes, volcanic activity and wind shear. [Ref: ATP GSC s. 6.22]
  143. 6-143. Refer to the following:

    UA/OV CYDC/TM 2330/FL085/TP C182/SK CLR/TA 28/WV 27020/TB MDT/RM IN CLR

    At what time, altitude and location does this PIREP relate to?
    6-143 (Answer). This PIREP relates to a time of 2330Z at FL 085 over Princeton, BC (CYDC). [Ref: ATP GSC s. 6.23]
  144. 6-144. What is the purpose of an AIRMET?
    6-144 (Answer). The purpose of an AIRMET is to provide pilots with a short term weather advisory to aircraft in flight so as to notify of potential hazardous weather not in current GFAs and not severe enough to require a SIGMET. [Ref: ATP GSC s. 6.24]
  145. 6-145. Provide examples of un-anticipated weather that would lead to the issuance of an AIRMET.
    6-145 (Answer). Examples of un-anticipated weather that would lead to the issuing of an AIRMET include freezing precipitation, moderate icing, moderate turbulence, isolated thunderstorms, surface winds over an area increase to 20 kts or more, and when the difference in observed and forecast wind direction is greater than 60 degrees. [Ref: ATP GSC s. 6.24]
  146. 6-146. Where the term CAVOK is used in an ATIS broadcast, this indicates that the visibility will be at least how many miles?
    6-146 (Answer). Where the term CAVOK has been used in an ATIS broadcast, this indicates that the surface visibility is at least 6 SM. [Ref: ATP GSC s. 6.26]
  147. 6-147. What is the name of the surface weather chart that provides a forecast of anticipated weather at some specified time in the future?
    6-147 (Answer). A PROGNOSTIC SURFACE WEATHER CHART provides a forecast of anticipated weather at some specified time in the future. [Ref: ATP GSC s. 6.27]
  148. 6-148. What is the name of the surface weather chart that provides actual reported weather?
    6-148 (Answer). A SURFACE ANALYSIS WEATHER CHART provides actual reported weather. [Ref: ATP GSC s. 6.27]
  149. 6-149. Surface analysis charts represent weather up to what height above the surface?
    6-149 (Answer). Surface analysis charts indicate weather from the surface to 3,000 feet, and include weather visible from the surface at any level. [Ref: ATP GSC s. 6.27]
  150. 6-150. What information is presented based on the Station Model in respect of a given station on a surface analysis chart?
    6-150 (Answer). The weather information that is presented based on the Station Model for a given station on a surface analysis chart includes the station's sky and cloud cover, temperature, dewpoint, surface wind, present visibility and weather, sea level pressure and remarks. [Ref: ATP GSC s. 6.27]
  151. 6-151. Where an area of a surface prognostic chart has been coloured in yellow shading, what does this indicate in terms of the expected weather for the area?
    6-151 (Answer). Where an area of a surface prognostic chart has been shaded in yellow, this indicates that fog is expected for the area. [Ref: ATP GSC s. 6.27]
  152. 6-152. With respect to the symbols used on a surface weather chart, which symbol below represents frontogenesis of a cold front?
    6-152 (Answer). On a surface weather chart, Illustration "I" represents frontogenesis of a cold front. [Ref: ATP GSC s. 6.27]
  153. 6-153. With respect to the symbols used on a surface weather chart, which symbol represents a stationary front?
    6-153 (Answer). With respect to the symbols used on a surface weather chart, symbol "L" represents a stationary front. [Ref: ATP GSC s. 6.27]
  154. 6-154. What is indicated by symbol "D" where used on a surface weather chart?
    6-154 (Answer). Symbol "D" where used on a surface weather chart represents a rain shower. [Ref: ATP GSC s. 6.27]
  155. 6-155. Does a Surface Analysis chart present weather based on existing reported weather, or is it a forecast for weather in the future?
    6-155 (Answer). A surface analysis chart presents weather based on existing reported weather. [Ref: ATP GSC s. 6.27]
  156. 6-156. Where a surface analysis weather chart has been issued, at the time of issue, it will be approximately how old based on the data used?
    6-156 (Answer). Where a surface analysis chart has been issued, at its time of issue, it will already be about 3 hours old i.e. the data used to construct the chart will have been based on observations taken about 3 hours in the past. [Ref: ATP GSC s. 6.27]
  157. 6-157. What is the difference between an upper level prognostic chart as compared to an upper level analysis chart?
    6-157 (Answer). An upper level prognostic chart is a forecast of predicted weather for some time in the future, while an upper level analysis chart presents actual reported weather for a given time. [Ref: ATP GSC s. 6.28]
  158. 6-158. How often and at what times per day are upper level analysis charts issued?
    6-158 (Answer). Upper level analysis charts are issued for the 850 mb, 700 mb, 500 mb and 250 mb pressure levels twice daily at 00Z and at 12Z. [Ref: ATP GSC s. 6.28]
  159. 6-159. What is the approximate altitude for the 850 mb pressure level?
    6-159 (Answer). The approximate altitude for the 850 mb pressure level is 5,000 feet ASL. [Ref: ATP GSC s. 6.28]
  160. 6-160. What is the approximate altitude for the 700 mb pressure level?
    6-160 (Answer). The approximate altitude for the 700 mb pressure level is 10,000 feet. [Ref: ATP GSC s. 6.28]
  161. 6-161. What is the approximate altitude for the 500 mb pressure level?
    6-161 (Answer). The approximate altitude for the 500 mb pressure level is 18,000 feet ASL. [Ref: ATP GSC s. 6.28]
  162. 6-162. What is the approximate altitude for the 250 mb pressure level?
    6-162 (Answer). The approximate altitude for the 250 mb pressure level is 34,000 feet. [Ref: ATP GSC s. 6.28]
  163. 6-163. What is the approximate altitude for the 150 mb pressure level?
    6-163 (Answer). The approximate altitude for the 150 mb pressure level is 45,000 feet. [Ref: ATP GSC s. 6.28]
  164. 6-164. What is a "Contour Line" in respect of an upper level chart?
    6-164 (Answer). The term CONTOUR LINE refers to a line that joins all points of equal height of a specific pressure level on an upper level chart. For example, on the 500 mb Analysis chart, contour lines would show the height pattern of the 500 mb pressure level. [Ref: ATP GSC s. 6.28]
  165. 6-165. Refer to the 500 mb analysis chart at Fig. 6-30. What is the height of the 500 mb pressure level at the centre of the Low?
    6-165 (Answer). The height of the 500 mb pressure level is 5340 metres. This can be determined from the number "534" which represents the height of the low in decameters (tens of metres). [Ref: ATP GSC s. 6.28]
  166. 6-166. What is meant by the term "Isotherm" in respect of upper level charts?
    6-166 (Answer). An ISOTHERM is a dashed, red line that joins all points of equal temperature on an upper level chart. [Ref: ATP GSC s. 6.28]
  167. 6-167. What is meant by the term "Isotach" in respect of an upper level chart?
    6-167 (Answer). An ISOTACH is an area of shading or clear area within boundaries to show ranges of wind speed. [Ref: ATP GSC s. 6.28]
  168. 6-168. Refer to the 250 mb analysis chart at Fig. 6-31. What is the wind direction, wind speed and temperature for the 250 mb pressure level at the southern tip of Hudson's Bay/Jame's Bay?
    6-168 (Answer). At the southern tip of Hudson's Bay/Jame's Bay, for the 250 mb pressure level, the winds are from 200º T at 90 kts, and the temperature is -55º C. [Ref: ATP GSC s. 6.28]
  169. 6-169. What symbol below is used on upper level significant weather prognostic charts to indicate areas of severe icing?
    6-169 (Answer). Symbol G is used to indicate severe icing on upper level significant weather prognostic charts. [Ref: ATP GSC s. 6.28]
  170. 6-170. For what range of heights does the CMC 700 mb - 400 mb significant weather prognostic chart cover?
    6-170 (Answer). The CMC 700 - 400 mb Significant Weather Prognostic Chart covers altitudes between FL 100 to FL 240. [Ref: ATP GSC s. 6.28]
  171. 6-171. Where fronts have been indicated on upper level significant weather prognostic charts, are the fronts depicted on the basis of surface position, or on the basis of their upper level position?
    6-171 (Answer). On upper level significant weather prognostic charts, fronts are depicted on the basis of surface position. [Ref: ATP GSC s. 6.28]
  172. 6-172. Refer to Fig. 6-36. What is the forecast freezing level height over the eastern Great Lakes area?
    6-172 (Answer). The freezing level for the eastern Great Lakes area is at 10,000 feet ASL. [Ref: ATP GSC s. 6.28]
  173. 6-173. Refer to Fig. 6-36. For the eastern Great Lakes area, over what range of heights has icing been forecasted, and what degree of icing has been forecasted?
    6-173 (Answer). Over the eastern Great Lakes area, moderate icing has been forecasted from below the level of the chart upwards to 16,000 feet ASL. [Ref: ATP GSC s. 6.28]
  174. 6-174. Refer to Fig. 6-36. Over the eastern Great Lakes area, to what maximum height has cloud been forecast, and what will be the horizontal coverage of this cloud?
    6-174 (Answer). Over the eastern Great Lakes area, cloud layers have been forecasted to reach 16,000 feet in layers, and the amount of coverage is forecasted to be 8/8. [Ref: ATP GSC s. 6.28]
  175. 6-175. Refer to Fig. 6-37. What is the role of this aviation chart?
    6-175 (Answer). This aviation chart is an upper level prognostic significant weather chart, and it is designed to show forecast significant weather from FL 250 to FL 600. [Ref: ATP GSC s. 6.28]
  176. 6-176. Refer to Fig. 6-37. What is the forecast lowest height of the tropopause over central Saskatchewan?
    6-176 (Answer). The forecast lowest height of the tropopause over central Saskatchewan is at 28,000 feet. [Ref: ATP GSC s. 6.28]
  177. 6-177. Where CB cells are indicated as "ISOL" on upper level significant weather prognostic charts, what area will the isolated CB's cover?
    6-177 (Answer). CB's indicated as ISOL on upper level significant weather prognostic charts will cover less than 1/8 of the area indicated. [Ref: ATP GSC s. 6.28]
  178. 6-178. Where CB's are indicated as OCNL on an upper level significant weather prognostic chart, what area will the CB's cover?
    6-178 (Answer). Where CB's are described as OCNL on upper level significant weather prognostic charts, this indicates that the CB's are well separated and will cover from 1/8 to 4/8's of the area indicated. [Ref: ATP GSC s. 6.28]
  179. 6-179. Where CB's are indicated as "FRQ" on an upper level significant weather prognostic chart, what area will the CB's cover?
    6-179 (Answer). Where CB's are described as FRQ on upper level significant weather prognostic charts, this indicates that the CB's have little or no separation and cover from 5/8 - 8/8 of the area indicated. [Ref: ATP GSC s. 6.28]
  180. 6-180. What is automatically implied by the use of the symbol "CB" on uppler level prognostic charts in terms of turbulence, hail and icing?
    6-180 (Answer). The use of the symbol "CB" on upper level significant weather prognostic charts automatically implies moderate or greater turbulence, hail and icing. [Ref: ATP GSC s. 6.28]
  181. 6-181. Refer to Fig. 6-37. What is the height of the tropopause at the Saskatchewan/USA international border?
    6-181 (Answer). The height of the tropopause at the Saskatchewan/USA border is 30,000 feet ASL. [Ref: ATP GSC s. 6.28]
  182. 6-182. Refer to Fig. 6-37. What is indicated where a double hatched line crosses a jet stream on an upper level significant weather prognostic chart?
    6-182 (Answer). Where a double hatched line crosses a jet stream depicted on an upper level significant weather prognostic chart, this indicates a change in the speed of the jet of 20 kts at 100 kts, 120 kts and 140 kts or higher. [Ref: ATP GSC s. 6.28]
  183. 6-183. Refer to Fig. 6-37. There is a jet stream depicted just to the west of Greenland and east of Baffin Island. What is the peak speed of this jet stream?
    6-183 (Answer). The peak speed of the jet stream to the west of Greenland and east of Baffin Island is 120 kts, as can be confirmed by two darkened triangles (50 kts each) with two pennants (10 kts each). [Ref: ATP GSC s. 6.28]
  184. 6-184. Refer to Fig. 6-37. In relation to the jet stream off the coast of Greenland, as this jet stream reaches the southern tip of Greenland and turns eastward, where the double hatched line cross the jet stream (at the approximate southern end of Greenland), what is the speed of the jet stream at this point?
    6-184 (Answer). The speed of the jet stream off the west of Greenland where the double hatched line crosses (at about the southern end of Greenland) is 100 kts. This hatched line represents a drop in speed from the maximum of 120 kts indicated further north. Note how if we continue to follow this jet stream into the mid-Atlantic, it increases to 110 kts. [Ref: ATP GSC s. 6.28]
  185. 6-185. Refer to Fig. 6-34. What is the reported upper wind speed, direction and temperature for FL 450 at the Bay of Fundy/Nova Scotia area?
    6-185 (Answer). At FL 450 for the Bay of Fundy/Nova Scotia area, upper level winds are from 240º T at 40 kts, with an upper temperature of -62º C. [Ref: ATP GSC s. 6.28]
  186. 6-186. Jet streams are depicted on upper level significant weather prognostic charts where the core speed of the jet stream will be at least how fast?
    6-186 (Answer). Jet streams are depicted on upper level significant weather prognostic charts where the core speed of the jet stream will be at least 80 kts. [Ref: ATP GSC s. 6.28]
  187. 6-187. At what times of day are high level (FL 250 FL 600) significant weather prognostic charts issued for?
    6-187 (Answer). High level significant weather prognostic charts are issued for forecast times 00Z, 06Z, 12Z and 18Z. Remember, these are prognostic charts so they tell us the forecast weather for the time indicated at a given time in the future. [Ref: ATP GSC s. 6.28]
  188. 6-188. What is the meaning of the term "Macro Wave Trough"?
    6-188 (Answer). On upper air charts, the pattern provided by the pressure contours forms curved lines, and where this pattern is characterized by low pressures, this is termed a MACRO WAVE TROUGH. [Ref: ATP GSC s. 6.28]
  189. 6-189. Is a Macro Wave Trough as indicated by the pressure contours on an upper level chart an indication of good weather or of poor weather?
    6-189 (Answer). A Macro Wave Trough as indicated by the pressure contours on an upper level chart is an indicator of poor weather i.e. low pressure type weather patterns. [Ref: ATP GSC s. 6.28]

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