12 practice questions from the 259 in this chapter of StudyWren Aviation. Pick an answer and check it to see the explanation and its FAA source.
Atmospheric StabilityPAR-08-240
The surface temperature is 30°C, and a sounding shows 20°C at 5,000 feet AGL. If a parcel is lifted from the surface to 5,000 feet and remains unsaturated, how will it behave?
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The answer is B: It will be about 15°C, colder than its surroundings, so it is stable
An unsaturated parcel cools at 3°C per 1,000 feet: 30 - (3 x 5) = 15°C. The environment at 5,000 feet is 20°C, so the parcel is colder and denser and tends to sink back: stable for unsaturated air. The environmental lapse rate here is only 2°C per 1,000 feet.
The answer is B: It will be about 15°C, colder than its surroundings, so it is stable
An unsaturated parcel cools at 3°C per 1,000 feet: 30 - (3 x 5) = 15°C. The environment at 5,000 feet is 20°C, so the parcel is colder and denser and tends to sink back: stable for unsaturated air. The environmental lapse rate here is only 2°C per 1,000 feet.
A large high-pressure area is centered directly south of your route in the Northern Hemisphere. You are flying westbound at 6,000 feet along its northern side. What wind should you generally expect?
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The answer is C: A headwind from the west
Air circulates clockwise around a Northern Hemisphere high, so along its northern side the flow is from west to east. That westerly wind is a headwind for a westbound flight; eastbound pilots look for the northern side of a high (or the southern side of a low) to get a tailwind.
Air circulates clockwise around a Northern Hemisphere high, so along its northern side the flow is from west to east. That westerly wind is a headwind for a westbound flight; eastbound pilots look for the northern side of a high (or the southern side of a low) to get a tailwind.
Approaching to land near a thunderstorm, you fly into heavy rain but notice no increase in airspeed. Why should you not conclude that there is no microburst ahead?
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The answer is A: In an asymmetric microburst the initial headwind gain can be small or absent
Microburst outflow can be asymmetric, so a significant airspeed increase may not occur on entering the outflow or may be much smaller than the airspeed loss that follows. Headwind shears should not be relied upon to give early warning of the tailwind shear.
The answer is A: In an asymmetric microburst the initial headwind gain can be small or absent
Microburst outflow can be asymmetric, so a significant airspeed increase may not occur on entering the outflow or may be much smaller than the airspeed loss that follows. Headwind shears should not be relied upon to give early warning of the tailwind shear.
According to the AIM, lightning strikes to aircraft are most likely at altitudes where the outside air temperature is between
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The answer is C: -5°C and +5°C
The AIM states that the probability of lightning strikes is greatest when operating at altitudes where temperatures are between -5°C and +5°C, and that lightning can strike aircraft flying in clear air near a thunderstorm.
The AIM states that the probability of lightning strikes is greatest when operating at altitudes where temperatures are between -5°C and +5°C, and that lightning can strike aircraft flying in clear air near a thunderstorm.
From a distance, one thunderstorm looks smaller and less threatening than a darker storm nearby. What can you conclude about the turbulence inside the smaller storm?
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The answer is A: Nothing reliable, since appearance does not indicate internal turbulence
FAA guidance is not to trust the visual appearance of a thunderstorm as a reliable indicator of the turbulence inside it; there is no useful correlation between external appearance and the severity of turbulence or hail. Every thunderstorm should be treated as hazardous.
The answer is A: Nothing reliable, since appearance does not indicate internal turbulence
FAA guidance is not to trust the visual appearance of a thunderstorm as a reliable indicator of the turbulence inside it; there is no useful correlation between external appearance and the severity of turbulence or hail. Every thunderstorm should be treated as hazardous.
Two thunderstorms producing intense radar echoes are about 25 miles apart, with clear air visible between them. What does FAA guidance say about flying between them?
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The answer is B: Avoid the gap; intense echoes should be at least 40 miles apart
Guidance is to avoid severe or intense echoes by at least 20 miles, which means such echoes should be separated by at least 40 miles before flying between them. The AIM adds that no path between strong echoes separated by 20 to 30 miles or less can be considered free of severe turbulence.
The answer is B: Avoid the gap; intense echoes should be at least 40 miles apart
Guidance is to avoid severe or intense echoes by at least 20 miles, which means such echoes should be separated by at least 40 miles before flying between them. The AIM adds that no path between strong echoes separated by 20 to 30 miles or less can be considered free of severe turbulence.
A funnel-shaped cloud extends down from a cumulonimbus base but does not reach the ground. What is it called?
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The answer is A: A funnel cloud
If the vortex cloud does not reach the surface it is a funnel cloud; if it touches land it is a tornado, and if it touches water it is a waterspout. Any of them indicates an extremely dangerous circulation that may extend unseen into the cloud.
If the vortex cloud does not reach the surface it is a funnel cloud; if it touches land it is a tornado, and if it touches water it is a waterspout. Any of them indicates an extremely dangerous circulation that may extend unseen into the cloud.
Heavy rain, but no hail, is reported at the surface beneath a large thunderstorm near your route. What should you assume about hail?
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The answer is C: Hail may exist aloft even though only rain reaches the ground
Hailstones melt as they fall through above-freezing air, so precipitation may reach the ground as rain. Rain at the surface does not mean hail is absent aloft; anticipate hail with any thunderstorm, especially beneath the anvil.
The answer is C: Hail may exist aloft even though only rain reaches the ground
Hailstones melt as they fall through above-freezing air, so precipitation may reach the ground as rain. Rain at the surface does not mean hail is absent aloft; anticipate hail with any thunderstorm, especially beneath the anvil.
Significant precipitation usually requires clouds that are at least how thick?
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The answer is B: About 4,000 feet
The FAA notes that significant precipitation usually requires clouds at least 4,000 feet thick, and the heavier the precipitation, the thicker the clouds are likely to be. When an airport reports light or greater precipitation, expect clouds more than 4,000 feet thick.
The FAA notes that significant precipitation usually requires clouds at least 4,000 feet thick, and the heavier the precipitation, the thicker the clouds are likely to be. When an airport reports light or greater precipitation, expect clouds more than 4,000 feet thick.
Almost all structural icing occurs within which outside air temperature range?
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The answer is A: 0°C to -20°C
Icing requires temperatures below 0°C, and as clouds get colder their supercooled water content decreases until only ice crystals remain. Almost all icing occurs between 0°C and -20°C, with about half of reports between -8°C and -12°C; -40°C is the physical cold limit.
Icing requires temperatures below 0°C, and as clouds get colder their supercooled water content decreases until only ice crystals remain. Almost all icing occurs between 0°C and -20°C, with about half of reports between -8°C and -12°C; -40°C is the physical cold limit.
In winter, very cold, dry arctic air flows off a continent and over a relatively warm ocean for several days, picking up warmth and moisture. How is the modified air mass best classified?
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The answer is A: Maritime polar (mP)
Cold, dry arctic air moving over warmer water picks up moisture and some warmth but remains fairly cold, so after several days it is a maritime polar (mP) air mass. It started as continental arctic (cA), but the ocean moisture source makes it maritime.
Cold, dry arctic air moving over warmer water picks up moisture and some warmth but remains fairly cold, so after several days it is a maritime polar (mP) air mass. It started as continental arctic (cA), but the ocean moisture source makes it maritime.
A dryline passes your airport on the southern Plains during the afternoon. Which changes are typical?
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The answer is C: Humidity drops sharply, skies clear, and the wind shifts to west or southwest
A dryline passage brings a sharp drop in humidity, clearing skies, and a wind shift from south or southeast to west or southwest, sometimes with blowing dust and rising temperatures. The reverse occurs when it retreats westward at night.
The answer is C: Humidity drops sharply, skies clear, and the wind shifts to west or southwest
A dryline passage brings a sharp drop in humidity, clearing skies, and a wind shift from south or southeast to west or southwest, sometimes with blowing dust and rising temperatures. The reverse occurs when it retreats westward at night.
