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CTS - Aviation Weather Theory
Questions and Answers Graded A+
Standard Atmosphere was created by: ✔✔Averaging conditions to create an idealized atmosphere.
The standard temperature lapse rate in the lower layers of the atmosphere is: ✔✔A decrease of 2 ° C per 1,000'.
If the air temperature is +8°C at an elevation of 1,350 feet MSL and a standard (average) temperature lapse rate exists, what will be the approximate freezing level? ✔✔5,350 feet MSL.
Moving up in the atmosphere, unsaturated air gets cooler at approximately what rate (dry adiabatic lapse rate)? ✔✔3°C per 1,000 feet.
A common type of ground or surface based temperature inversion is that which is produced by: ✔✔Ground radiation on clear, cool nights when the wind is light.
A temperature inversion will normally form only: ✔✔In stable air.
Which weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high? ✔✔Smooth air and poor visibility due to fog, haze, or low clouds.
The earth's atmosphere is primarily composed of: ✔✔Nitrogen.
Which of the following layers of the atmosphere extends from the surface to an altitude of about 20,000' over the poles and 48,000' over the equatorial regions? ✔✔Troposphere.
In the lower layers of the atmosphere, pressure decreases with an increase in altitude at a rate of approximately: ✔✔1 inch per 1,000 feet.
An increase in temperature with altitude is known as an: ✔✔Inverted lapse rate.
Which condition would cause the true altitude of the aircraft to be lower than the indicated altitude, even if the altimeter is accurate? ✔✔Temperature colder than standard.
Which of the following terms describes the amount of water vapor present compared to the total water vapor possible at a given temperature and is given as a percentage? ✔✔Relative humidity.
The temperature to which the air must be cooled to become saturated by the water vapor already present in the air is known as the: ✔✔Dew point.
Which changes of state of moisture absorb heat energy? ✔✔Evaporation and melting.
Microscopic particles of salt, dust, and combustion byproducts are necessary for water vapor molecules to change state from gas to liquid or solid. These are called: ✔✔Condensation nuclei.
Supercooled water droplets are abundant in clouds at temperatures from: ✔✔0° to -15° C
Most clouds are formed because the air: ✔✔Is cooled.
Which of the following are forms of precipitation? ✔✔All of the answers are correct.
Which is most related to the intensity of precipitation? ✔✔Cloud thickness.
Which condition would most likely produce fog? ✔✔Temperature-dew point spread is 5 °F (2. °C) and decreasing.
When air is lifted it: ✔✔Cools due to decreasing pressure.
Compare the rate of cooling when saturated air is lifted to the rate of cooling when unsaturated air is lifted. ✔✔The rate of cooling in saturated air is slower.
Which condition would result in the air becoming unstable? The temperature of: ✔✔The air which was lifted is warmer than the surrounding air temperature.
Which type of clouds are most likely to form in moist stable air? ✔✔Stratiform.
Which type of clouds are most likely to form when there is a rapid decrease in temperature with an increase in altitude? ✔✔Cumuliform.
Which cloud belongs to the family of "vertically developed" clouds? ✔✔Towering cumulus.
Which type of clouds are associated with a mountain wave? ✔✔Rotor clouds and altocumulus standing lenticular clouds.
Clouds, fog, or dew will always form when: ✔✔Water vapor condenses.
What type of clouds will be formed if very stable moist air is forced up slope? ✔✔Stratified clouds with little vertical development.
What type clouds can be expected when an unstable air mass is forced to ascend a mountain slope? ✔✔Clouds with extensive vertical development.
What determines the structure or type of clouds which form as a result of air being forced to ascend? ✔✔The stability of the air before lifting occurs.
Which of the following combinations of weather producing variables would likely result in cumuliform-type clouds, good visibility, rain showers, and possible clear-type icing in clouds? ✔✔Unstable, moist air, and orographic lifting.
Which family of clouds is least likely to contribute to structural icing on an aircraft? ✔✔High clouds.
What are the four families of clouds? ✔✔High, middle, low, and those with extensive vertical development.
During a hot summer afternoon along coastal areas, which will most likely form along the shoreline? ✔✔Cumuliform clouds.
The zone between two air masses of different properties is called: ✔✔A front.
Which of the following properties always changes across a front? ✔✔Which of the following properties always changes across a front?
Which of these best describes a cold front? ✔✔The leading edge of an advancing cold air mass.
A front is defined as stationary if: ✔✔Neither air mass is replacing the other.
An air mass passing over a warmer surface results in the formation of what? ✔✔Convective currents.
An air mass that moves out of its source region will: ✔✔Become modified taking on characteristics of the surface below.
Wind shear may exist: ✔✔All of the answers are correct.
Wind shear associated with a low level temperature inversion can cause an aircraft to stall. How should you alleviate this danger? ✔✔Allow a margin of airspeed above normal approach speed.
What is a characteristic of low-level wind shear as it relates to frontal activity? ✔✔With a warm front, the most critical period is before the front passes the airport.
Standing lenticular clouds, in mountainous areas, typically indicate which of the following conditions? ✔✔Turbulence.
Wind shear associated with a thunderstorm is commonly found where? Choose the most complete answer. ✔✔On all sides of the thunderstorm cell and directly under the cell.
Where does wind shear occur? ✔✔With either a wind shift or a wind speed gradient at any level in the atmosphere.
A jet stream is defined as wind of: ✔✔50 knots or greater.
Clear air turbulence is strongest on what side of a jet stream? ✔✔The cold side
If, while in flight, an area of severe turbulence is encountered, which flight condition should you attempt to maintain? ✔✔A level flight attitude.
A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as: ✔✔Light turbulence.
What is the expected duration of an individual microburst? ✔✔Seldom longer than 15 minutes from the time the burst strikes the ground until dissipation.
On a warm day when flying at a lower altitude, a pilot might experience turbulence associated with ____________ as they transition from flight over a field with a crop growing to flight over a plowed field. ✔✔Convective currents.
What are the two conditions necessary for structural icing to form in flight? ✔✔Temperatures freezing or below and visible liquid moisture.
Which type of icing is hard, heavy, tenacious, and most difficult to break off with deicing equipment? ✔✔Clear.
Which condition would be most likely for the formation of rime ice? ✔✔Light drizzle or stratus clouds.
Ice forming on the static ports would cause which of the following instruments to be unreliable? ✔✔Airspeed indicator, altimeter, and VSI.
Which of the following determines the severity of icing? ✔✔Size of the water droplets and temperature.
Around what temperatures would the heaviest icing most probably be found in a thick nimbostratus cloud? ✔✔Temperatures at or slightly below freezing.
Which condition is most favorable for rapid accumulation of clear ice? ✔✔Freezing rain below a frontal surface.
If flying in IFR conditions and you encounter freezing rain beneath the frontal slope, what is the best procedure to avoid icing? ✔✔Climb to an altitude above the frontal slope where you will encounter above freezing temperatures.
An accumulation of frost on the airfoil surface could cause which of the following? ✔✔A 5% to 10% increase in stall speed for airplanes and a loss of lift for helicopters.
If you must climb through a layer of icing, which is the best procedure? ✔✔Use an airspeed a little faster than normal climb speed.
At which temperature range would you expect to encounter the heaviest icing in cumuliform clouds? ✔✔0° to -15° C.
Which is the most likely time for on-shore and off-shore thunderstorms to form? ✔✔Off-shore at night and on-shore during the afternoon.
Which type of thunderstorm tends to form with frontal weather systems? ✔✔Steady state thunderstorms.
A thunderstorm cloud which displays rounded, irregular pockets or festoons from its base is called "cumulonimbus mammatus". This type of cloud is a signpost of: ✔✔Violent turbulence.
A non-frontal narrow band of active thunderstorms which presents the single most intense weather hazard to aircraft is known as a: ✔✔Squall line.
One of the greatest hazards of thunderstorms is hail, which is a hazard: ✔✔Even miles away from the storm cloud.
Which is prevalent with cold frontal or squall line thunderstorms and signifies an extremely turbulent zone? ✔✔Roll cloud.
Which is the best indication as to the intensity of a thunderstorm? ✔✔The more frequent the lightning, the more intense the storm.
You should avoid any thunderstorm identified as severe by at least: ✔✔20 nautical miles.
If using airborne radar and flying in the vicinity of thunderstorms, what is a good procedure? ✔✔Tilt the antenna up and down occasionally.
Which is a good procedure if you are flying near a thunderstorm at night? ✔✔Turn the instrument lights to high intensity.
True or false? If you encounter a cumulonimbus cloud that doesn't appear to be producing rain, hail, or lightning, it is safe to pass nearby. ✔✔False.
The rapid and drastic changes in ___________ associated with a passing thunderstorm can cause the altimeter to be more than 100 feet in error. ✔✔Pressure.
Which areas would be most conducive to the formation of fog? ✔✔Coastal areas and industrial areas.
What is the primary difference between a ceiling caused by an obstruction to vision and one caused by clouds? ✔✔Obstructions to vision are based on the surface whereas clouds are based aloft.
Which of these conditions might produce fog? ✔✔All of the answers are correct.
What type of fog tends to form when air is blowing from a cold surface over warmer water? ✔✔Steam fog.
When a high pressure stagnates over an industrial area, during which time of the day would you expect the lowest visibility? ✔✔Early morning.
How long does it normally take radiation or ground fog to burn off? ✔✔1 to 3 hours.
Which two types of fog could form even though the skies are cloudy? ✔✔Advection and upslope fog.
When is the temperature at one of the forecast altitudes omitted at a specific location or station in the Winds and Temperatures Aloft Forecast (FD)? ✔✔For the 3,000-foot altitude (level) or when the level is within 2,500 feet of station elevation.
What conclusion(s) can be drawn from a Constant Pressure Chart? ✔✔Observed temperature, wind, and temperature/dewpoint spread along the proposed route can be approximated.
On which chart(s) would you find information on lines and cells of hazardous thunderstorms? ✔✔Radar Summary Chart.
SIGMETs are issued as a warning of weather conditions that are potentially hazardous: ✔✔To all aircraft.
A pilot planning to depart at 1100Z on an IFR flight is particularly concerned about the hazard of icing. What sources reflect the most accurate information on icing conditions (current and forecast) at the time of departure? ✔✔Pilot weather reports (PIREPs), AIRMETs, and SIGMETs.
When are severe weather watch bulletins (WW) issued? ✔✔Unscheduled and issued as required.
