Commercial Ground - Weather

Moisture is added to air by a. sublimation and condensation. b. evaporation and condensation. c. evaporation and sublimation.

evaporation and sublimation. Evaporation is the changing of liquid water to invisible water vapor. Sublimation is the changing of ice directly to water vapor. Answer (A) is incorrect because condensation removes moisture from the air. Answer (B) is incorrect because condensation removes moisture from the air.

Fog produced by frontal activity is a result of saturation due to a. nocturnal cooling. b. adiabatic cooling. c. evaporation of precipitation.

evaporation of precipitation. When relatively warm rain or drizzle falls through cool air, evaporation from the precipitation saturates the cool air and forms fog. Answer (A) is incorrect because nocturnal cooling produces radiation fog. Answer (B) is incorrect because adiabatic cooling produces upslope fog.

The greatest threats to an aircraft operating in the vicinity of thunderstorms are: a. thunder and heavy rain. b. hail and turbulence. c. precipitation static and low visibility.

hail and turbulence. Hazardous turbulence is present in all thunderstorms; in a severe thunderstorm, it can damage an airframe. Hail competes with turbulence as the greatest thunderstorm hazard to aircraft.

When flying into a low-pressure area in the Northern Hemisphere, the wind direction and velocity will be from the a. left and decreasing. b. left and increasing. c. right and decreasing.

left and increasing. In the Northern Hemisphere the wind around a low is counterclockwise. Thus, when flying to the center of a low, the wind will be from the left. When flying into a pressure system, spacing between isobars will decrease with increasing wind velocity.

The general circulation of air associated with a high-pressure area in the Northern Hemisphere is a. outward, downward, and clockwise. b. outward, upward, and clockwise. c. inward, downward, and clockwise.

outward, downward, and clockwise. As the air tries to blow outward from the high pressure, it is deflected to the right by the Coriolis force. Thus, the wind around a high blows clockwise. Air moving out of a high depletes the quantity of air. Highs and ridges are areas of descending air.

What prevents air from flowing directly from high-pressure areas to low-pressure areas? a. Coriolis force. b. Surface friction. c. Pressure gradient force.

Coriolis force. The pressure gradient force drives the wind and is perpendicular to isobars. When a pressure gradient force is first established, wind begins to blow from higher to lower pressure directly across the isobars. However, the instant air begins moving, Coriolis force deflects it to the right. Soon the wind is deflected a full 90° and is parallel to the isobars or contours. At this time, Coriolis force exactly balances pressure gradient force. With the forces in balance, wind will remain parallel to isobars or contours. Answer (B) is incorrect because surface friction moves air from highs to lows by decreasing wind speed, which decreases the effect of the Coriolis force. Answer (C) is incorrect because the pressure gradient force causes the initial movement from high-pressure areas to low-pressure areas.

What visible signs indicate extreme turbulence in thunderstorms? a. Base of the clouds near the surface, heavy rain, and hail. b. Low ceiling and visibility, hail, and precipitation static. c. Cumulonimbus clouds, very frequent lightning, and roll clouds.

Cumulonimbus clouds, very frequent lightning, and roll clouds. Cumulonimbus clouds represent an unstable air mass which indicates turbulent conditions. The more frequent the lightning, the more severe the thunderstorm. The roll cloud is most prevalent with cold frontal or squall line thunderstorms and signifies an extremely turbulent zone.

During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts? a. Mature. b. Developing. c. Dissipating.

Dissipating. Downdrafts characterize the dissipating stage of the thunderstorm cell. Answer (A) is incorrect because the mature stage has both updrafts and downdrafts. Answer (B) is incorrect because the developing stage primarily has updrafts.

What is indicated if ice pellets are encountered at 8,000 feet? a. Freezing rain at higher altitude. b. You are approaching an area of thunderstorms. c. You will encounter hail if you continue your flight.

Freezing rain at higher altitude. Rain falling from warm air above through colder air below may freeze during its descent, falling as ice pellets. This can happen any time a warmer layer of air exists above a colder layer (i.e., a warm front or a cold front). Answer (B) is incorrect because freezing rain can be encountered without thunderstorms. Answer (C) is incorrect because ice pellets are a form of hail.

Which statement is true concerning the hazards of hail? a. Hail damage in horizontal flight is minimal due to the vertical movement of hail in the clouds. b. Rain at the surface is a reliable indication of no hail aloft. c. Hailstones may be encountered in clear air several miles from a thunderstorm.

Hailstones may be encountered in clear air several miles from a thunderstorm. Hailstones can fall some distance from the storm core. Hail has been observed in clear air several miles from the parent thunderstorm. Answer (A) is incorrect because hail is one of the greatest hazards to aircraft. Answer (B) is incorrect because rain at the surface does not mean the absence of hail aloft.

With respect to advection fog, which statement is true? a. It is slow to develop, and dissipates quite rapidly. b. It forms almost exclusively at night or near daybreak. c. It can appear suddenly during day or night, and it is more persistent than radiation fog.

It can appear suddenly during day or night, and it is more persistent than radiation fog. Advection fog is more persistent than radiation fog and can move in rapidly regardless of the time of day or night. Answer (A) is incorrect because advection fog can move in rapidly regardless of the time of day or night and is persistent. Answer (B) is incorrect because this describes radiation fog.

What is an important characteristic of wind shear? a. It is present at only lower levels and exists in a horizontal direction. b. It is present at any level and exists in only a vertical direction. c. It can be present at any level and can exist in both a horizontal and vertical direction.

It can be present at any level and can exist in both a horizontal and vertical direction. Wind shear may be associated with either a wind shift or a wind speed gradient at any level in the atmosphere. It may be associated with a low-level temperature inversion, in a frontal zone, or clear air turbulence (CAT) at high levels associated with a jet stream or strong circulation. Answer (A) is incorrect because wind shear occurs both vertically and horizontally, and at all altitudes. Answer (B) is incorrect because wind shear occurs both vertically and horizontally, and at all altitudes.

What are the characteristics of stable air? a. Good visibility; steady precipitation; stratus clouds. b. Poor visibility; steady precipitation; stratus clouds. c. Poor visibility; intermittent precipitation; cumulus clouds.

Poor visibility; steady precipitation; stratus clouds. Characteristics of stable air include stratiform clouds and fog, continuous precipitation, smooth air, and fair to poor visibility in haze and smoke. Answer (A) is incorrect because good visibility is characteristic of unstable air. Answer (C) is incorrect because intermittent precipitation and cumulus clouds are characteristic of unstable air.

Which in-flight hazard is most commonly associated with warm fronts? a. Advection fog. b. Radiation fog. c. Precipitation-induced fog.

Precipitation-induced fog. When relatively warm rain or drizzle falls through cool air, evaporation from the precipitation saturates the cool air and forms fog. Precipitation-induced fog can become quite dense and continue for an extended period of time. This fog may cover large areas, completely suspending air operations. It is most commonly associated with warm fronts, but can occur with slow moving cold fronts and with stationary fronts. Answer (A) is incorrect because advection fog forms from the movement of warm, humid air over a cold water surface. Answer (B) is incorrect because radiation fog forms from terrestrial cooling of the Earth's surface on clear, calm nights.

What causes wind? a. The Earth's rotation. b. Air mass modification. c. Pressure differences.

Pressure differences. Differences in temperature create differences in pressure. These pressure differences drive a complex system of winds in a never-ending attempt to reach equilibrium.

In what ways do advection fog, radiation fog, and steam fog differ in their formation or location? a. Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface. b. Advection fog deepens as windspeed increases up to 20 knots; steam fog requires calm or very light wind; radiation fog forms when the ground or water cools the air by radiation. c. Steam fog forms from moist air moving over a colder surface; advection fog requires cold air over a warmer surface; radiation fog is produced by radiational cooling of the ground.

Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface. Radiation fog is restricted to land areas because water surfaces cool little from nighttime radiation. Advection fog is most common along coastal areas but often develops deep in continental areas. Steam fog, also known as 'sea smoke,' forms in the winter when cold, dry air passes from land areas over comparatively warm ocean waters.

Which is a characteristic of stable air? a. Cumuliform clouds. b. Excellent visibility. c. Restricted visibility.

Restricted visibility. Characteristics typical of a stable air mass are: - Stratiform clouds and fog - Continuous precipitation - Smooth air - Fair to poor visibility in haze and smoke Answer (A) is incorrect because cumuliform clouds and excellent visibility are characteristic of an unstable air mass. Answer (B) is incorrect because cumuliform clouds and excellent visibility are characteristic of an unstable air mass.

When an air mass is stable, which of these conditions are most likely to exist? a. Numerous towering cumulus and cumulonimbus clouds. b. Moderate to severe turbulence at the lower levels. c. Smoke, dust, haze, etc., concentrated at the lower levels with resulting poor visibility.

Smoke, dust, haze, etc., concentrated at the lower levels with resulting poor visibility. Characteristics typical of a stable air mass are: - Stratiform clouds and fog - Continuous precipitation - Smooth air - Fair to poor visibility in haze and smoke Answer (A) is incorrect because towering cumulus, cumulonimbus clouds, and turbulence are characteristic of an unstable air mass. Answer (B) is incorrect because towering cumulus, cumulonimbus clouds, and turbulence are characteristic of an unstable air mass.

From which measurement of the atmosphere can stability be determined? a. Atmospheric pressure. b. The ambient lapse rate. c. The dry adiabatic lapse rate.

The ambient lapse rate. A change in ambient temperature lapse rate of an air mass will determine its stability. Surface heating or cooling aloft can make the air more unstable. On the other hand, surface cooling or warming aloft often tips the balance toward greater stability. Answer (A) is incorrect because atmospheric pressure affects temperature and air movements, but does not determine the stability of the atmosphere. Answer (C) is incorrect because the dry adiabatic lapse rate is a constant rate.

The conditions necessary for the formation of cumulonimbus clouds are a lifting action and a. unstable, dry air. b. stable, moist air. c. unstable, moist air.

unstable, moist air. For cumulonimbus clouds to form, the air must have sufficient water vapor, an unstable lapse rate, and an initial upward boost (lifting) to start the storm process in motion.

If airborne radar is indicating an extremely intense thunderstorm echo, this thunderstorm should be avoided by a distance of at least a. 20 miles. b. 10 miles. c. 5 miles.

20 miles. If the use of airborne radar indicates extremely intense echoes, they should be avoided by at least 20 miles.

What minimum distance should exist between intense radar echoes before any attempt is made to fly between these thunderstorms? a. 20 miles. b. 30 miles. c. 40 miles.

40 miles. A pilot should avoid flying between very intense echoes unless they are separated by at least 40 miles.

What is the approximate base of the cumulus clouds if the temperature at 2,000 feet MSL is 10°C and the dewpoint is 1°C? a. 3,000 feet MSL. b. 4,000 feet MSL. c. 6,000 feet MSL.

6,000 feet MSL. In a convection current, the temperature and dewpoint converge at about 2.5°C per 1,000 feet. An estimate of convective cloud bases can be found by dividing the convergence into the temperature spread. 1. (10 - 1) ÷ 2.5 = 3.6 x 1,000 = 3,600 feet base 2. 2,000 feet MSL + 3,600 feet AGL = 5,600 feet MSL.

Refer to the excerpt from the following METAR report:KTUS.....08004KT 4SM HZ .....26/04 A2995 RMK RAE36At approximately what altitude AGL should bases of convective-type cumuliform clouds be expected? a. 4,400 feet. b. 8,800 feet. c. 17,600 feet.

8,800 feet. The reported temperature is 26°C, and the dewpoint is 4°C. In a convection current, the temperature and dewpoint converge at about 4.4°F (2.5°C) per 1,000 feet. An estimate of convective cloud bases can be found by dividing the convergence into the temperature spread. (26 - 4) ÷ 2.5 = 8.8 x 1,000 = 8,800 feet base.

Which type of jetstream can be expected to cause the greater turbulence? a. A straight jetstream associated with a low-pressure trough. b. A curving jetstream associated with a deep low-pressure trough. c. A jetstream occurring during the summer at the lower latitudes.

A curving jetstream associated with a deep low-pressure trough. Curving jet streams, especially those which curve around a deep pressure trough, are more apt to have turbulent edges than straight jet streams. Answer (A) is incorrect because a curving jet stream is stronger than a straight jet stream. Answer (C) is incorrect because the jet stream is weaker in the summer.

You have delayed your flight to allow a fast moving cold front to clear your destination airport before your arrival. What type of flying conditions would you expect after the front has passed? a. A fast moving squall line with high winds and thunderstorms. b. Clear skies with gusty, turbulent winds and cooler temperatures. c. Low clouds, reduced visibility, and showery, misty conditions.

A fast moving squall line with high winds and thunderstorms. Thunderstorms and heavy rain are common although not always associated with cold fronts.

Which is true with respect to a high- or low-pressure system? a. A high-pressure area or ridge is an area of rising air. b. A low-pressure area or trough is an area of descending air. c. A high-pressure area or ridge is an area of descending air.

A high-pressure area or ridge is an area of descending air. Air moving out of a high or ridge depletes the quantity of air. Highs and ridges, therefore, are areas of descending air. Answer (A) is incorrect because high-pressure air descends. Answer (B) is incorrect because low-pressure air rises.

Which is true regarding high- or low-pressure systems? a. A high-pressure area or ridge is an area of rising air. b. A low-pressure area or trough is an area of rising air. c. Both high- and low-pressure areas are characterized by descending air.

A low-pressure area or trough is an area of rising air. At the surface when air converges into a low, it cannot go outward against the pressure gradient, nor can it go downward into the ground. It must go upward. Therefore, a low or trough is an area of rising air. Answer (A) is incorrect because high-pressure air descends and low-pressure air rises. Answer (C) is incorrect because high-pressure air descends and low-pressure air rises.

What are the characteristics of an unstable atmosphere? a. A cool, dry air mass. b. A warm, humid air mass. c. Descending air in the northern hemisphere.

A warm, humid air mass. Characteristics of unstable air include cumuliform clouds, showery precipitation, turbulence, and good visibility, except in blowing obstructions.

Which feature is associated with the tropopause? a. Constant height above the Earth. b. Abrupt change in temperature lapse rate. c. Absolute upper limit of cloud formation.

Abrupt change in temperature lapse rate. As the thin boundary layer between the troposphere and the stratosphere, the tropopause signals an abrupt change in temperature lapse rate. Answer (A) is incorrect because the tropopause is farther away from the Earth's surface at the equator than the poles. Answer (C) is incorrect because clouds may form above the tropopause.

Thunderstorms identified as severe or giving an intense radar echo should be avoided by what distance? a. 5 miles. b. At least 25 miles. c. At least 20 miles.

At least 20 miles. Avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus.

Which conditions are favorable for the formation of a surface based temperature inversion? a. Clear, cool nights with calm or light wind. b. Area of unstable air rapidly transferring heat from the surface. c. Broad areas of cumulus clouds with smooth, level bases at the same altitude.

Clear, cool nights with calm or light wind. An inversion often develops near the ground on clear, cool nights when the wind is light. Answer (B) is incorrect because the air near the surface must be stable to permit the cool ground to lower the temperature of the surrounding air. Answer (C) is incorrect because cumulus clouds are well above the surface.

Which is a characteristic typical of a stable air mass? a. Cumuliform clouds. b. Showery precipitation. c. Continuous precipitation.

Continuous precipitation. Characteristics typical of a stable air mass are: - Stratiform clouds and fog - Continuous precipitation - Smooth air - Fair to poor visibility in haze and smoke Answer (A) is incorrect because cumuliform clouds and showery precipitation are characteristic of an unstable air mass. Answer (B) is incorrect because cumuliform clouds and showery precipitation are characteristic of an unstable air mass.

What feature is normally associated with the cumulus stage of a thunderstorm? a. Roll cloud. b. Continuous updraft. c. Beginning of rain at the surface.

Continuous updraft. The key feature of the cumulus stage of a thunderstorm is a continuous updraft. Answer (A) is incorrect because the roll cloud and the beginning of rain at the surface are features of the mature stage. Answer (C) is incorrect because the roll cloud and the beginning of rain at the surface are features of the mature stage.

Which would increase the stability of an air mass? a. Warming from below. b. Cooling from below. c. Decrease in water vapor.

Cooling from below. A change in ambient temperature lapse rate of an air mass will determine its stability. Surface cooling or warming aloft often tips the balance toward greater stability. Answer (A) is incorrect because warming from below decreases stability. Answer (C) is incorrect because a decrease in water vapor lowers the dewpoint of the air, but does not affect stability.

Why does the wind have a tendency to flow parallel to the isobars above the friction level? a. Coriolis force tends to counterbalance the horizontal pressure gradient. b. Coriolis force acts perpendicular to a line connecting the highs and lows. c. Friction of the air with the Earth deflects the air perpendicular to the pressure gradient.

Coriolis force tends to counterbalance the horizontal pressure gradient. The pressure gradient force drives the wind and is perpendicular to isobars. When a pressure gradient force is first established, wind begins to blow from higher to lower pressure directly across the isobars. However, the instant air begins moving, Coriolis force deflects it to the right. Soon the wind is deflected a full 90° and is parallel to the isobars or contours. At this time, Coriolis force exactly balances pressure gradient force. With the forces in balance, wind will remain parallel to isobars or contours.

Which are characteristics of a cold air mass moving over a warm surface? a. Cumuliform clouds, turbulence, and poor visibility. b. Cumuliform clouds, turbulence, and good visibility. c. Stratiform clouds, smooth air, and poor visibility.

Cumuliform clouds, turbulence, and good visibility. Cool air moving over a warm surface is heated from below, generating instability and increasing the possibility of showers. Unstable air is characterized by cumuliform clouds, turbulence and good visibility.

Of the following, which is accurate regarding turbulence associated with thunderstorms? a. Outside the cloud, shear turbulence can be encountered 50 miles laterally from a severe storm. b. Shear turbulence is encountered only inside cumulonimbus clouds or within a 5-mile radius of them. c. Outside the cloud, shear turbulence can be encountered 20 miles laterally from a severe storm.

Outside the cloud, shear turbulence can be encountered 20 miles laterally from a severe storm. Hazardous turbulence is present in all thunderstorms, and a severe thunderstorm can damage an airframe. Strongest turbulence within the clouds occurs with shear between updrafts and downdrafts. Outside the cloud, shear turbulence has been encountered several thousand feet above and 20 miles laterally from a severe storm.

What is a characteristic of stable air? a. Stratiform clouds. b. Fair weather cumulus clouds. c. Temperature decreases rapidly with altitude.

Stratiform clouds. Characteristics of stable air include stratiform clouds and fog, continuous precipitation, smooth air, and fair to poor visibility in haze and smoke. Answer (B) is incorrect because cumulus clouds are characteristic of unstable air. Answer (C) is incorrect because a rapid temperature decrease with altitude indicates a high lapse rate and is characteristic of unstable air.

What type weather can one expect from moist, unstable air, and very warm surface temperatures? a. Fog and low stratus clouds. b. Continuous heavy precipitation. c. Strong updrafts and cumulonimbus clouds.

Strong updrafts and cumulonimbus clouds. Characteristics of unstable air include cumuliform clouds, showery precipitation, turbulence, and good visibility, except in blowing obstructions. Answer (A) is incorrect because fog and stratus clouds are characteristics of stable air. Answer (B) is incorrect because continuous precipitation is characteristic of stable air.

When conditionally unstable air with high-moisture content and very warm surface temperature is forecast, one can expect what type of weather? a. Strong updrafts and stratonimbus clouds. b. Restricted visibility near the surface over a large area. c. Strong updrafts and cumulonimbus clouds.

Strong updrafts and cumulonimbus clouds. Characteristics of unstable air include cumuliform clouds, showery precipitation, turbulence, and good visibility, except in blowing obstructions. Answer (A) is incorrect because stratonimbus clouds are characteristic of stable air. Answer (B) is incorrect because restricted visibility is characteristic of stable air.

What lifts advection fog into low stratus clouds? a. Nighttime cooling. b. Dryness of the underlying land mass. c. Surface winds of approximately 15 knots or stronger.

Surface winds of approximately 15 knots or stronger. Advection fog deepens as wind speed increases up to about 15 knots. Winds much stronger than 15 knots lift the fog into a layer of low stratus clouds or stratocumulus. Answer (A) is incorrect because nighttime cooling and dryness of the underlying land mass lead to radiation fog. Answer (B) is incorrect because nighttime cooling and dryness of the underlying land mass lead to radiation fog.

During departure, under conditions of suspected low-level wind shear, a sudden decrease in headwind will cause a. a loss in airspeed equal to the decrease in wind velocity. b. a gain in airspeed equal to the decrease in wind velocity. c. no change in airspeed, but groundspeed will decrease.

a loss in airspeed equal to the decrease in wind velocity. The worst situation on departure occurs when the aircraft encounters a rapidly increasing tailwind, decreasing headwind, and/or downdraft. Taking off under these circumstances would lead to a decreased performance condition. An increasing tailwind or decreasing headwind, when encountered, will cause a decrease in indicated airspeed. The aircraft will initially pitch down due to the decreased lift in proportion to the airspeed loss. After encountering the shear, if the wind remains constant, aircraft ground speed will gradually increase and indicated airspeed will return to its original value. Answer (B) is incorrect because a sudden decrease in headwind will cause a loss in airspeed. Answer (C) is incorrect because there is an initial loss of airspeed, followed by an increase in ground speed.

Ice pellets encountered during flight normally are evidence that a. a warm front has passed. b. a warm front is about to pass. c. there are thunderstorms in the area.

a warm front is about to pass. Rain falling from warm air above through colder air below may freeze during its descent, falling as ice pellets. This can happen any time a warmer layer of air exists above a colder layer (i.e., a warm front or a cold front). Answer (A) is incorrect because after the warm front has passed there will no longer be a layer of warm air above a layer of cold air, which is required for the formation of ice pellets. Answer (C) is incorrect because ice pellets do not necessarily come from thunderstorms, but from rain freezing at a higher altitude.

A situation most conducive to the formation of advection fog is a. a light breeze moving colder air over a water surface. b. an air mass moving inland from the coastline during the winter. c. a warm, moist air mass settling over a cool surface under no-wind conditions.

an air mass moving inland from the coastline during the winter. Advection fog forms when warm, moist air moves over colder ground or water. The fog forms offshore and is then carried inland by the wind. It is most common along coastal areas but often develops deep in continental areas. Answer (A) is incorrect because this describes steam fog. Answer (C) is incorrect because this describes radiation fog.

While flying cross-country, in the Northern Hemisphere, you experience a continuous left crosswind which is associated with a major wind system. This indicates that you a. are flying toward an area of generally unfavorable weather conditions. b. have flown from an area of unfavorable weather conditions. c. cannot determine weather conditions without knowing pressure changes.

are flying toward an area of generally unfavorable weather conditions. When flying in the Northern Hemisphere experiencing a continuous left crosswind indicates that you are entering a low-pressure system. Wind blows counterclockwise around a low which accounts for the left crosswind. In general, a low-pressure system is associated with bad weather. Answer (B) is incorrect because if you have flown from an area of unfavorable weather conditions, you are flying out of the low, which means you would have a right crosswind. Answer (C) is incorrect because the wind can provide an indication of pressure changes and weather.

One of the most dangerous features of mountain waves is the turbulent areas in and a. below rotor clouds. b. above rotor clouds. c. below lenticular clouds.

below rotor clouds. 'Rotor clouds' appear to remain stationary, parallel the range, and stand a few miles leeward of the mountains. Turbulence is most frequent and most severe in and below the standing rotors just beneath the wave crests at or below mountain-top levels.

The low-level wind shear Alert System (LLWAS) provides wind data and software process to detect the presence of a a. rotating column of air extending from a cumulonimbus cloud. b. change in wind direction and/or speed within a very short distance above the airport. c. downward motion of the air associated with continuous winds blowing with an easterly component due to the rotation of the Earth.

change in wind direction and/or speed within a very short distance above the airport. Wind shear may be associated with either a wind shift or a wind speed gradient at any level in the atmosphere. It may be associated with a low-level temperature inversion, in a frontal zone, or clear air turbulence (CAT) at high levels associated with a jet stream or strong circulation. Answer (A) is incorrect because this describes a tornado. Answer (C) is incorrect because LLWAS detects wind changes close to the airport.

With regard to windflow patterns shown on surface analysis charts; when the isobars are a. close together, the pressure gradient force is slight and wind velocities are weaker. b. not close together, the pressure gradient force is greater and wind velocities are stronger. c. close together, the pressure gradient force is greater and wind velocities are stronger.

close together, the pressure gradient force is greater and wind velocities are stronger. The closer the spacing of isobars, the stronger is the pressure gradient force. The stronger the pressure gradient force, the stronger is the wind. Thus, closely spaced isobars mean strong winds; widely spaced isobars mean lighter wind.

A moist, unstable air mass is characterized by a. poor visibility and smooth air. b. cumuliform clouds and showery precipitation. c. stratiform clouds and continuous precipitation.

cumuliform clouds and showery precipitation. Characteristics of unstable air include cumuliform clouds, showery precipitation, turbulence, and good visibility, except in blowing obstructions. Answer (A) is incorrect because poor visibility and smooth air are characteristic of stable air. Answer (C) is incorrect because stratiform clouds and continuous precipitation are characteristic of stable air.

Hail is most likely to be associated with a. cumulus clouds. b. cumulonimbus clouds. c. stratocumulus clouds.

cumulonimbus clouds. You should anticipate possible hail with any thunderstorm, especially beneath the anvil of a large cumulonimbus.

Which is true regarding actual air temperature and dewpoint temperature spread? The temperature spread a. decreases as the relative humidity decreases. b. decreases as the relative humidity increases. c. increases as the relative humidity increases.

decreases as the relative humidity increases. The difference between air temperature and dewpoint temperature is called the 'spread.' As the spread becomes less, relative humidity increases.

Ice pellets encountered during flight are normally evidence that a. a cold front has passed. b. there are thunderstorms in the area. c. freezing rain exists at higher altitudes.

freezing rain exists at higher altitudes. Rain falling from warm air above through colder air below may freeze during its decent, falling as ice pellets. This can happen any time a warmer layer of air exists above a colder layer (i.e., a warm front or a cold front).

A common location of clear air turbulence is a. in an upper trough on the polar side of a jet stream. b. near a ridge aloft on the equatorial side of a high-pressure flow. c. south of an east/west oriented high-pressure ridge in its dissipating stage.

in an upper trough on the polar side of a jet stream. Clear air turbulence (CAT) is greatest near the wind speed maxima, usually on the polar sides where there is a combination of strong wind shear, curvature in the flow, and cold air advection associated with sharply curved contours of strong lows, troughs and ridges aloft. A frequent location of CAT is in an upper trough on the cold, or polar side of the jet stream.

Hazardous wind shear is commonly encountered a. near warm or stationary frontal activity. b. when the wind velocity is stronger than 35 knots. c. in areas of temperature inversion and near thunderstorms.

in areas of temperature inversion and near thunderstorms. Often there is a strong wind just above the top of an inversion layer. Flying into or out of this wind induces a shear situation. The most prominent meteorological phenomena that cause significant low-level wind shear problems are thunderstorms and certain frontal systems at or near the airport. Answer (A) is incorrect because hazardous wind shear is more commonly found near inversions and thunderstorms. Answer (B) is incorrect because strong wind does not mean that there will always be wind shear; the wind must be in different directions.

GIVEN:Winds at 3,000 feet AGL 30 kts Surface winds CalmWhile on approach for landing under clear skies with convective turbulence a few hours after sunrise, one should a. increase approach airspeed slightly above normal to avoid stalling. b. keep the approach airspeed at or slightly below normal to compensate for floating. c. not alter the approach airspeed, these conditions are nearly ideal.

increase approach airspeed slightly above normal to avoid stalling. When taking off or landing in calm wind under clear skies within a few hours before or after sunrise, be prepared for a temperature inversion near the ground. You can be relatively certain of a shear zone in the inversion if you know the wind at 2,000 to 4,000 feet is 25 knots or more. Increase airspeed slightly above normal climb or approach speed to alleviate the danger of a stall in event of turbulence or sudden change in wind velocity. Answer (B) is incorrect because the hazard is wind shear. Answer (C) is incorrect because these conditions are not ideal - wind shear may be present.

Which is true regarding a cold front occlusion? The air ahead of the warm front a. is colder than the air behind the overtaking cold front. b. is warmer than the air behind the overtaking cold front. c. has the same temperature as the air behind the overtaking cold front.

is warmer than the air behind the overtaking cold front. In the cold front occlusion, the coldest air is under the cold front. When it overtakes the warm front, it lifts the warm front aloft and cold air replaces cool air at the surface.

When flying low over hilly terrain, ridges, or mountain ranges, the greatest potential danger from turbulent air currents will usually be encountered on the a. leeward side when flying with a tailwind. b. leeward side when flying into the wind. c. windward side when flying into the wind.

leeward side when flying into the wind. Dangerous downdrafts may be encountered on the lee side. Answer (A) is incorrect because with a tailwind you would be flying away from the mountain with the wind. Answer (C) is incorrect because you would be flying in air that is rising up on the windward side.

Convective currents are most active on warm summer afternoons when winds are a. light. b. moderate. c. strong.

light. Convective currents are most active on warm summer afternoons when winds are light. Heated air at the surface creates a shallow, unstable layer and the warm air is forced upward. Convection increases in strength and to greater heights as surface heating increases. Answer (B) is incorrect because moderate and strong winds disrupt the vertical movement of convective currents. Answer (C) is incorrect because moderate and strong winds disrupt the vertical movement of convective currents.

The jet stream and associated clear air turbulence can sometimes be visually identified in flight by a. dust or haze at flight level. b. long streaks of cirrus clouds. c. a constant outside air temperature.

long streaks of cirrus clouds. Long streaks of cirrus clouds can sometimes help the pilot to visually identify the jet stream and associated clear air turbulence (CAT). Answer (A) is incorrect because dust or haze indicates there is not enough wind or air movement to dissipate the particles. Answer (C) is incorrect because CAT is caused by mixing different air temperatures at different pressure levels.

Which situation would most likely result in freezing precipitation? Rain falling from air which has a temperature of a. 32°F or less into air having a temperature of more than 32°F. b. 0°C or less into air having a temperature of 0°C or more. c. more than 32°F into air having a temperature of 32°F or less.

more than 32°F into air having a temperature of 32°F or less. Rain falling through colder air may become supercooled, freezing on impact as freezing rain, or it may freeze during its descent, falling as ice pellets. Water can freeze at 0°C or 32°F.

A strong wind shear can be expected a. in the jetstream front above a core having a speed of 60 to 90 knots. b. if the 5°C isotherms are spaced between 7° to 10° of latitude. c. on the low-pressure side of a jetstream core where the speed at the core is stronger than 110 knots.

on the low-pressure side of a jetstream core where the speed at the core is stronger than 110 knots. Jet streams stronger than 110 knots (at the core) are apt to have areas of significant turbulence near them in the sloping tropopause above the core, in the jet stream front below the core and on the low-pressure side of the core. In these areas there are frequently strong wind shears. Answer (A) is incorrect because 60 to 90 knots is common for the jet stream and if turbulence were to be found it would be to the sides and bottom of the core. Answer (B) is incorrect because these conditions do not exclusively create wind shear.

There is a high pressure system that is located south of your planned route in the Northern Hemisphere on a west to east cross-country flight. To take advantage of favorable winds, you would plan your route a. on the north side of the high pressure area. b. on the south side of the high pressure area. c. through the middle of the high pressure area.

on the north side of the high pressure area. High pressure flows outward in a clockwise direction so pilot will gain tailwinds by flying on the north side of the high pressure system.

During an approach, the most important and most easily recognized means of being alerted to possible wind shear is monitoring the a. amount of trim required to relieve control pressures. b. heading changes necessary to remain on the runway centerline. c. power and vertical velocity required to remain on the proper glidepath.

power and vertical velocity required to remain on the proper glidepath. Since rate of descent on the glide slope is directly related to ground speed, a high descent rate would indicate a strong tailwind. Conversely, a low descent rate indicates a strong headwind. The power needed to hold the glide slope also will be different from typical, no-shear conditions. Less power than normal will be needed to maintain the glide slope when a tailwind is present and more power is needed for strong headwind. Answer (A) is incorrect because trim adjustments are a function of power settings, airspeeds, and aircraft configuration. Answer (B) is incorrect because heading changes are due to the crosswind component.

In the Northern Hemisphere, the wind is deflected to the a. right by Coriolis force. b. right by surface friction. c. left by Coriolis force.

right by Coriolis force. The Coriolis force deflects air to the right in the Northern Hemisphere.

During the winter months in the middle latitudes, the jet stream shifts toward the a. north and speed decreases. b. south and speed increases. c. north and speed increases.

south and speed increases. In middle latitudes, the wind speed of the jet stream averages considerably higher in the winter months as it shifts farther south.

The most severe weather conditions, such as destructive winds, heavy hail, and tornadoes, are generally associated with a. slow-moving warm fronts which slope above the tropopause. b. squall lines. c. fast-moving occluded fronts.

squall lines. A squall line is a non-frontal, narrow band of active thunderstorms. It often contains severe steady-state thunderstorms and presents the single most intense weather hazard to aircraft. Answer (A) is incorrect because warm fronts do not usually produce severe weather. Answer (C) is incorrect because the weather produced by occluded fronts is not as severe as a squall line.

The formation of either predominantly stratiform or predominantly cumuliform clouds is dependent upon the a. source of lift. b. stability of the air being lifted. c. temperature of the air being lifted.

stability of the air being lifted. When stable air is forced upward, the air tends to retain horizontal flow. Any cloudiness is flat and stratified. When unstable air is forced upward, the disturbance grows, and any resulting cloudiness shows extensive vertical development. Answer (A) is incorrect because the stability of the air determines the type of clouds that form. Answer (C) is incorrect because the temperature of the air determines the altitude of clouds that form.

The conditions most favorable to wave formation over mountainous areas are a layer of a. stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge. b. unstable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge. c. moist, unstable air at mountaintop altitude and a wind of less than 5 knots blowing across the ridge.

stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge. A strong mountain wave requires: 1. Marked stability in the airstream disturbed by the mountains; 2. Wind speed at the level of the summit should exceed a minimum which varies from 15 to 25 knots, depending on the height of the range; and 3. Wind direction within 30° to the range. Lift diminishes as winds more closely parallel the range.

The conditions necessary for the formation of stratiform clouds are a lifting action and a. unstable, dry air. b. stable, moist air. c. unstable, moist air.

stable, moist air. Stable, moist air and adiabatic cooling is necessary to form stratiform clouds.

If clouds form as a result of very stable, moist air being forced to ascend a mountain slope, the clouds will be a. cirrus type with no vertical development or turbulence. b. cumulus type with considerable vertical development and turbulence. c. stratus type with little vertical development and little or no turbulence.

stratus type with little vertical development and little or no turbulence. Stable air resists upward movement; therefore, stratified clouds are produced. Answer (A) is incorrect because cirrus clouds are high and composed of ice crystals. Answer (B) is incorrect because unstable air causes vertical development.

Virga is best described as a. streamers of precipitation trailing beneath clouds which evaporates before reaching the ground. b. wall cloud torrents trailing beneath cumulonimbus clouds which dissipate before reaching the ground. c. turbulent areas beneath cumulonimbus clouds.

streamers of precipitation trailing beneath clouds which evaporates before reaching the ground. 'Virga' refers to the streamers of precipitation trailing beneath clouds that evaporate before reaching the ground. Answer (B) is incorrect because virga is usually thin and wispy. Answer (C) is incorrect because virga is a form of precipitation.

Frost covering the upper surface of an airplane wing usually will cause a. the airplane to stall at an angle of attack that is higher than normal. b. the airplane to stall at an angle of attack that is lower than normal. c. drag factors so large that sufficient speed cannot be obtained for takeoff.

the airplane to stall at an angle of attack that is lower than normal. The frost on the wing causes airflow disturbances. This will cause airflow separation (stall) at a lower angle of attack, resulting in a tendency to stall during takeoff. Answer (A) is incorrect because frost on the wing surface will usually cause the airplane to stall at a lower angle of attack. Answer (C) is incorrect because the drag will usually not be enough to prevent the aircraft from obtaining takeoff speed.

Low-level wind shear may occur when a. surface winds are light and variable. b. there is a low-level temperature inversion with strong winds above the inversion. c. surface winds are above 15 knots and there is no change in wind direction and windspeed with height.

there is a low-level temperature inversion with strong winds above the inversion. When taking off or landing in calm wind under clear skies within a few hours before or after sunrise, be prepared for a temperature inversion near the ground. You can be relatively certain of a shear zone in the inversion if you know the wind at 2,000 to 4,000 feet is 25 knots or more. Allow a margin of airspeed above normal climb or approach speed to alleviate the danger of a stall in event of turbulence or sudden change in wind velocity. Answer (A) is incorrect because light surface winds alone would not cause wind shear. Answer (C) is incorrect because wind shear refers to an abrupt change in wind speed and/or direction.

Select the true statement pertaining to the life cycle of a thunderstorm. a. Updrafts continue to develop throughout the dissipating stage of a thunderstorm. b. The beginning of rain at the Earth's surface indicates the mature stage of the thunderstorm. c. The beginning of rain at the Earth's surface indicates the dissipating stage of the thunderstorm.

The beginning of rain at the Earth's surface indicates the mature stage of the thunderstorm. The mature stage of a thunderstorm starts when precipitation begins to fall from the cloud base. The downdrafts reach speeds that may exceed 2,500 feet per minute. Meanwhile, updrafts reach a maximum with speeds possibly exceeding 6,000 feet per minute. Updrafts and downdrafts in close proximity create strong vertical shear and a very turbulent environment. Answer (A) is incorrect because updrafts do not continue through the dissipating stage of a thunderstorm. Answer (C) is incorrect because this indicates the beginning of the mature stage.

Which is true regarding the use of airborne weather-avoidance radar for the recognition of certain weather conditions? a. The radarscope provides no assurance of avoiding instrument weather conditions. b. The avoidance of hail is assured when flying between and just clear of the most intense echoes. c. The clear area between intense echoes indicates that visual sighting of storms can be maintained when flying between the echoes.

The radarscope provides no assurance of avoiding instrument weather conditions. Weather radar detects only precipitation drops. It does not detect minute cloud droplets. Therefore, the radar scope provides no assurance of avoiding instrument weather in clouds and fog. Answer (B) is incorrect because hail can be thrown several miles from the intense echoes. Answer (C) is incorrect because clouds without precipitation may exist between the echoes.

What determines the structure or type of clouds which will form as a result of air being forced to ascend? a. The method by which the air is lifted. b. The stability of the air before lifting occurs. c. The relative humidity of the air after lifting occurs.

The stability of the air before lifting occurs. Whether the air is stable or unstable within a layer largely determines cloud structure. When stable air is forced upward the air tends to retain horizontal flow and any cloudiness is flat and stratified. When unstable air is forced upward, the disturbance grows and any resulting cloudiness shows extensive vertical development. Answer (A) is incorrect because the stability determines the type of clouds that form. Answer (C) is incorrect because the relative humidity determines the amount of clouds that form.

Which weather phenomenon signals the beginning of the mature stage of a thunderstorm? a. The start of rain. b. The appearance of an anvil top. c. Growth rate of cloud is maximum.

The start of rain. The mature stage of a thunderstorm starts when precipitation begins to fall from the cloud base. The downdrafts reach speeds that may exceed 2,500 feet per minute. Meanwhile, updrafts reach a maximum with speeds possibly exceeding 6,000 feet per minute. Answer (B) is incorrect because the anvil top appears during the mature stage, but not necessarily at the beginning. Answer (C) is incorrect because maximum cloud growth rate occurs in the middle to the end of the mature stage.

Which statement is true regarding squall lines? a. They are always associated with cold fronts. b. They are slow in forming, but rapid in movement. c. They are nonfrontal and often contain severe, steady-state thunderstorms.

They are nonfrontal and often contain severe, steady-state thunderstorms. A squall line is a non-frontal, narrow band of active thunderstorms. It often contains severe steady-state thunderstorms and presents the single most intense weather hazard to aircraft. Answer (A) is incorrect because squall lines can form in any area of unstable air, but usually are found ahead of cold fronts. Answer (B) is incorrect because squall lines usually form quickly.

Which statement is true concerning squall lines? a. They form slowly, but move rapidly. b. They are associated with frontal systems only. c. They offer the most intense weather hazards to aircraft.

They offer the most intense weather hazards to aircraft. A squall line is a non-frontal, narrow band of active thunderstorms. It often contains severe steady-state thunderstorms and presents the single most intense weather hazard to aircraft. Answer (A) is incorrect because squall lines usually form rapidly. Answer (B) is incorrect because squall lines can form in any area of unstable air, but usually are found ahead of cold fronts.

Which cloud types would indicate convective turbulence? a. Cirrus clouds. b. Nimbostratus clouds. c. Towering cumulus clouds.

Towering cumulus clouds. Billowy fair weather cumulus clouds, usually seen on sunny afternoons, are signposts in the sky indicating convective turbulence. Vertical heights range from the shallow fair weather cumulus to the giant thunderstorm cumulonimbus. Answer (A) is incorrect because cirrus clouds are high clouds made of ice crystals, and are not generated by any convective activity. Answer (B) is incorrect because nimbostratus clouds are flat rain clouds, formed in stable air and do not produce convective activity or turbulence.

Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility, and showery rain? a. Stable, moist air and orographic lifting. b. Unstable, moist air and orographic lifting. c. Unstable, moist air and no lifting mechanism.

Unstable, moist air and orographic lifting. Characteristics of unstable, moist air include cumuliform clouds, showery precipitation, turbulence, and good visibility, except in blowing obstructions. 'Orographic lifting' is the lifting action produced by a physical object, such as a mountain slope, forcing air upward. Answer (A) is incorrect because if the air is stable, steady precipitation and stratiform clouds will form. Answer (C) is incorrect because a lifting mechanism must exist to form cumuliform clouds and showery rain.

Which would decrease the stability of an air mass? a. Warming from below. b. Cooling from below. c. Decrease in water vapor.

Warming from below. A change in ambient temperature lapse rate of an air mass will determine its stability. Surface heating or cooling aloft can make the air more unstable. Answer (B) is incorrect because cooling from below increases stability. Answer (C) is incorrect because a decrease in water vapor lowers the dewpoint of the air, but does not affect stability.

Advection fog has drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into low stratus clouds? a. Nighttime cooling. b. Surface radiation. c. Wind 15 knots or stronger.

Wind 15 knots or stronger. Advection fog deepens as wind speed increases up to about 15 knots. Winds much stronger than 15 knots lift the fog into a layer of low stratus clouds or stratocumulus. Answer (A) is incorrect because nighttime cooling and surface radiation form radiation fog. Answer (B) is incorrect because nighttime cooling and surface radiation form radiation fog.

You are avoiding a thunderstorm that is in your flightpath. You are over 20 miles from the cell however, you are under the anvil of the cell. Is this a hazard? a. No, you are at a safe distance from the cell. b. Yes, hail can be discharged from the anvil. c. Yes, this is still in the area of dissipation.

Yes, hail can be discharged from the anvil. Avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus where hail can be discharged.

The wind system associated with a low-pressure area in the Northern Hemisphere is a. an anticyclone and is caused by descending cold air. b. a cyclone and is caused by Coriolis force. c. an anticyclone and is caused by Coriolis force.

a cyclone and is caused by Coriolis force. The storms that develop between high-pressure systems are characterized by low pressure. As winds try to blow inward toward the center of low pressure, they are also deflected to the right. Thus, the wind around a low moves in a counterclockwise direction. The low pressure and its wind system is a cyclone. Answer (A) is incorrect because they describe a high-pressure system. Answer (C) is incorrect because they describe a high-pressure system.

Density altitude is the vertical distance above mean sea level in the standard atmosphere at which a. pressure altitude is corrected for standard temperature. b. a given atmospheric density is to be found. c. temperature, pressure, altitude, and humidity are considered.

a given atmospheric density is to be found. Density altitude is the vertical distance above sea level in the standard atmosphere at which a given density is to be found. The density of air has significant effects on the aircraft's performance.

Every physical process of weather is accompanied by or is the result of a. a heat exchange. b. the movement of air. c. a pressure differential.

a heat exchange. The amount of solar energy received by any region varies with time of day, with seasons and with latitude. These differences in solar energy create temperature variation. Temperatures also vary with differences in topographical surface and with altitude. This temperature variation, or heat exchange, creates forces that drive the atmosphere in its endless motion. Answer (B) is incorrect because the movement of air and pressure differentials are caused by heat exchanges. Answer (C) is incorrect because the movement of air and pressure differentials are caused by heat exchanges.

During an IFR cross-country flight you picked up rime icing which you estimate is 1/2" thick on the leading edge of the wings. You are now below the clouds at 2000 feet AGL and are approaching your destination airport under VFR. Visibility under the clouds is more than 10 miles, winds at the destination airport are 8 knots right down the runway, and the surface temperature is 3 degrees Celsius. You decide to a. use a faster than normal approach and landing speed. b. approach and land at your normal speed since the ice is not thick enough to have any noticeable effect. c. fly your approach slower than normal to lessen the 'wind chill' effect and break up the ice.

use a faster than normal approach and landing speed. Ice will accumulate unevenly on the airplane. It will add weight and drag, and decrease thrust and lift. With ice accumulations, landing approaches should be made with a minimum wing flap setting and with an added margin of airspeed. Sudden and large configuration and airspeed changes should be avoided. Answer (B) is incorrect because ice having a thickness similar to sandpaper on the leading edge and upper surface of a wing can reduce wing lift by as much as 30% and increase drag by 40%. Answer (C) is incorrect because ice will increase drag, requiring additional lift (airspeed); 'wind chill' effect cannot be relied upon to melt/remove the ice that has already accumulated; flying slower than normal increases the possibility of a stall due to the decreased lift.

The presence of standing lenticular altocumulus clouds is a good indication of a. lenticular ice formation in calm air. b. very strong turbulence. c. heavy icing conditions.

very strong turbulence. Standing lenticular and/or rotor clouds suggest a mountain wave; expect turbulence many miles to the lee of mountains.

The strength and location of the jet stream is normally a. weaker and farther north in the summer. b. stronger and farther north in the winter. c. stronger and farther north in the summer.

weaker and farther north in the summer. The jet stream is considerably weaker in the middle latitudes during the summer months, and is further north than in the winter.

If a temperature inversion is encountered immediately after takeoff or during an approach to a landing, a potential hazard exists due to a. wind shear. b. strong surface winds. c. strong convective currents.

wind shear. You can be relatively certain of a shear zone in the inversion if you know the wind at 2,000 to 4,000 feet is 25 knots or more. Allow a margin of airspeed above normal climb or approach speed to alleviate the danger of a stall in event of turbulence or sudden change in wind velocity. Answer (B) is incorrect because strong surface winds do not present as great a danger as wind shear. Answer (C) is incorrect because a temperature inversion does not generate strong convective currents.