Private Pilot Weather Flashcards

An almond or lens-shaped cloud which appears stationary, but which may contain winds of 50 knots or more, is referred to as

Answer: a lenticular cloud.

An almond or lens-shaped cloud that appears stationary, often found near mountainous terrain, is characteristic of a lenticular cloud. These clouds form in stable air when strong winds blow across a mountain barrier, creating standing waves in the atmosphere. Despite their stationary appearance, the air within them can be moving at high speeds, posing a potential hazard to aircraft due to associated turbulence.

What is indicated when a current CONVECTIVE SIGMET forecasts thunderstorms?

Answer: Thunderstorms obscured by massive cloud layers.

A CONVECTIVE SIGMET is issued for significant weather phenomena associated with thunderstorms that are hazardous to all aircraft. One of the criteria for issuing a CONVECTIVE SIGMET is the presence of embedded thunderstorms. These are thunderstorms that are obscured by massive cloud layers, making them particularly dangerous as they are difficult for pilots to visually identify and avoid.

Crests of standing mountain waves may be marked by stationary, lens-shaped clouds known as

Answer: standing lenticular clouds.

When stable air flows over mountains, it can create standing waves in the atmosphere. The crests of these waves, where the air rises and cools, can lead to the formation of characteristic stationary, lens-shaped clouds. These are known as standing lenticular clouds, and they are a visual indicator of potential severe turbulence and strong winds associated with mountain wave activity.

The suffix "nimbus," used in naming clouds, means

Answer: a rain cloud.

In meteorology, the suffix "nimbus" (or prefix "nimbo-") is used in cloud names to indicate that the cloud is a rain-producing cloud. For example, nimbostratus clouds are layered rain clouds, and cumulonimbus clouds are towering thunderstorm clouds that produce heavy rain, lightning, and sometimes hail.

When may hazardous wind shear be expected?

Answer: In areas of low-level temperature inversion, frontal zones, and clear air turbulence.

Hazardous wind shear is a sudden change in wind speed or direction over a short distance, which can be extremely dangerous for aircraft, especially during takeoff and landing. It is commonly associated with several atmospheric conditions, including low-level temperature inversions, where a layer of warm air sits above colder air, frontal zones where two air masses meet, and clear air turbulence (CAT) often found near jet streams.

The amount of water vapor which air can hold depends on the

Answer: air temperature.

The amount of water vapor that air can hold is directly dependent on its temperature. Warmer air has a greater capacity to hold water vapor because the higher kinetic energy of the air molecules allows more water molecules to remain in a gaseous state. As air cools, its capacity to hold water vapor decreases, leading to condensation and the formation of clouds or precipitation if the dewpoint is reached.

What cloud types would indicate convective turbulence?

Answer: Towering cumulus clouds.

Convective turbulence is caused by vertical air currents resulting from uneven heating of the Earth's surface. Clouds with significant vertical development, such as towering cumulus clouds and cumulonimbus clouds, are strong indicators of active convection and therefore convective turbulence. These clouds are formed by rapidly rising warm air, which creates turbulent conditions within and around them.

When speaking to an AFSS weather briefer you should state

Answer: whether the flight is VFR or IFR.

When contacting an Automated Flight Service Station (AFSS) for a weather briefing, it is essential to provide specific information to ensure you receive the most relevant and accurate briefing. One crucial piece of information to state is whether the flight will be conducted under Visual Flight Rules (VFR) or Instrument Flight Rules (IFR). This allows the briefer to tailor the weather information to the specific requirements and regulations of your intended flight type.

(Refer to Figure 15.) What is the forecast wind for KMEM from 1600Z until the end of the forecast?

Answer: Variable in direction at 6 knots.

To determine the forecast wind for KMEM from 1600Z until the end of the forecast, locate the TAF for KMEM in Figure 15. Identify the forecast segment that begins at 1600Z and extends to the end of the forecast period. Within this segment, the wind information is typically presented as a direction and speed. Reading this portion of the TAF reveals a forecast of variable wind direction at 6 knots.

In which situation is advection fog most likely to form?

Answer: An air mass moving inland from the coast in winter.

Advection fog forms when warm, moist air moves horizontally over a cooler surface. As the warm, moist air passes over the colder ground or water, it cools to its dewpoint, causing the water vapor to condense into fog. This condition is most likely to occur when an air mass moves inland from the coast in winter, as the relatively warm and moist oceanic air encounters the colder land surface.

A weather briefing that is provided when the information requested is 6 or more hours in advance of the proposed departure time is

Answer: an outlook briefing.

An outlook briefing is a type of weather briefing provided by an AFSS when the proposed departure time is 6 or more hours in the future. This briefing provides a general overview of the weather conditions expected for the planned flight, allowing the pilot to make preliminary go/no-go decisions or to anticipate potential weather challenges well in advance. It is less detailed than a standard or abbreviated briefing.

(Refer to Figure 260, area D.) Immediately to the left of the letter D in western New York, what are the surface winds?

Answer: Wind 20 gusting to 30 kts.

To determine the surface winds immediately to the left of the letter D in western New York, locate Figure 260 and find the designated area D. On a surface analysis chart, wind information is typically depicted using wind barbs or symbols. These symbols indicate both wind direction and speed, including gusts. By interpreting the wind barb in that specific location, you can determine that the surface winds are 20 knots gusting to 30 knots.

If the temperature/dewpoint spread is small and decreasing, and the temperature is 62 °F, what type weather is most likely to develop?

Answer: Fog or low clouds.

The temperature/dewpoint spread is the difference between the ambient air temperature and the dewpoint temperature. When this spread is small and decreasing, it indicates that the air is approaching saturation. If the temperature continues to drop and reaches the dewpoint, the air will become saturated, leading to condensation and the formation of visible moisture in the form of fog or low clouds.

One of the most easily recognized discontinuities across a front is

Answer: a change in temperature.

A front is a boundary between two different air masses, each with distinct characteristics. One of the most easily recognized and significant discontinuities across a front is a change in temperature. As an air mass with different temperature characteristics replaces another, there is a noticeable shift in temperature across the frontal boundary, often accompanied by changes in wind direction, pressure, and moisture content.

A pilot can expect a wind-shear zone in a temperature inversion whenever the windspeed at 2,000 to 4,000 feet above the surface is at least

Answer: 25 knots.

FAA guidelines indicate that a wind shear zone can be expected in a temperature inversion when the wind speed at 2,000 to 4,000 feet above the surface is at least 25 knots. This significant difference in wind speed across the stable inversion layer creates strong shear forces. Such conditions pose a hazard to aircraft due to abrupt changes in airspeed and attitude.

At approximately what altitude above the surface would the pilot expect the base of cumuliform clouds if the surface air temperature is 82 °F and the dewpoint is 38 °F?

Answer: 10,000 feet AGL.

The base of cumuliform clouds can be estimated using the formula: (Surface Temperature - Surface Dewpoint) / 4.4 * 1000 feet AGL. With a surface temperature of 82°F and a dewpoint of 38°F, the difference is 44°F. Dividing 44 by 4.4 gives 10, and multiplying by 1,000 yields a cloud base of 10,000 feet AGL.

(Refer to Figure 17.) Determine the wind and temperature aloft forecast for DEN at 9,000 feet.

Answer: 230° true at 21 knots, temperature -4 °C.

Winds and Temperatures Aloft Forecasts (FDs) are decoded using a specific format. For DEN at 9,000 feet, the forecast group typically shows the first two digits as wind direction in tens of degrees true (e.g., 23 = 230°), the next two digits as wind speed in knots (e.g., 21 = 21 knots), and the last two digits as temperature in Celsius (e.g., -04 = -4°C). Therefore, 230° true at 21 knots, temperature -4°C is the correct interpretation.

What is meant by the term "dewpoint"?

Answer: The temperature to which air must be cooled to become saturated.

The dewpoint is defined as the temperature to which a parcel of air must be cooled, at constant pressure and moisture content, for it to become saturated. At this point, the air can no longer hold all of its water vapor, and condensation begins to form dew, fog, or clouds. It is a direct measure of the actual amount of water vapor in the air.

(Refer to Figure 19.) What weather is forecast for the Florida area just ahead of the stationary front during the first 12 hours?

Answer: Ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 miles with continuous precipitation.

Weather charts like Figure 19 use standard symbols to depict forecast conditions. For the area just ahead of a stationary front, the chart would indicate specific ceiling and visibility ranges along with the type and continuity of precipitation. The correct answer reflects the interpretation of these symbols, indicating Marginal VFR (MVFR) conditions with continuous precipitation, which is common in areas of persistent lifting ahead of a stationary front.

A temperature inversion would most likely result in which weather condition?

Answer: An increase in temperature as altitude is increased.

A temperature inversion is an atmospheric condition where the temperature of the air increases with altitude, rather than decreasing as is typical. This reversal of the normal temperature lapse rate creates a stable layer of air. While inversions can lead to poor visibility or fog, their defining characteristic is the increase in temperature as altitude is gained.