May 23, 2010

Interactive Quiz #150:
Cumulonimbi

Whatever the time of year, thunderstorms can be a real showstopper for flight. Test your knowledge of CBs and TCUs before your passengers can scream, "OMG!"

INSTRUCTIONS: Answer the questions as best you can, then click on the "Score my quiz answers" button to see your score and read the explanations. If you don't like your score the first time around, you can change some of your answers and resubmit. To get the most out of this quiz, we suggest you keep trying until you get a perfect score.

NOTE: When more than one answer is true, only the most complete, correct answer will be scored as correct. The answers are assumed to apply within the United States unless otherwise noted.

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1. According to the AIM (7-1-14), "Thunderstorms are a form of convective activity that implies severe or greater turbulence." Cool, sounds evil ... so, what is convection?
a. Thunder-induced rain
b. Transfer of heat energy in a fluid
c. Static-discharged atmospherics (sferics)
d. Unstable air with a non-standard lapse rate

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2. What three ingredients are generally needed to produce a thunderstorm?
a. Moisture, lifting action, unstable atmosphere
b. Moisture, stable atmosphere, heat
c. Wind shear, convection, clouds
d. Cold front, heat, unstable atmosphere

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3. What are the three, classic, textbook, memorized-this-in-ground-school-but-forgot-it-later stages of a thunderstorm's life cycle?
a. Cumulo, nimbus, dissipation
b. Updraft, updraft/downdraft, downdraft
c. Lifting, lightning, anvil
d. Cumulus, mature, dissipating

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4. What is the name given to "small-scale intense downdrafts, which, on reaching the surface, spread outward in all directions from the downdraft center"?
a. Wind shear
b. Minibursts
c. Microbursts
d. Low-level wind shear (LLWS)

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5. What type of cloud is the only type of cloud forecast in a TAF (Terminal Area Forecast or Aerodrome Forecast)?
a. Towering cumulus (TCU)
b. Cumulonimbus (CB)
c. Funnel
d. Water spout

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6. Select the term for "a line of thunderstorms often located along or ahead of a vigorous cold front."
a. Occlusion
b. Graupel
c. Dryline
d. Squall

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7. Pilots form the bigger weather picture using, in part, in-flight aviation weather advisories. Which in-flight advisory warns of embedded thunderstorms?
a. SIGMET
b. AIRMET
c. Convective SIGMET
d. Convective AIRMET

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8. Scenario: You're on an IFR clearance and being radar-vectored to a final approach course. Thunderstorms have been in the area throughout the day. The radar approach controller (not Center) is required to vector your target around any areas of known thunderstorm activity.
a. True
b. False

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9. A thunderstorm might be reported in a METAR (Aviation Routine Weather Report), but that same METAR does not say if the storm is severe, which would be kind-of nice to know. Which conditions below would indicate that the thunderstorm is considered severe?
a. Wind gusts greater than 50 knots, 3/4-inch hail
b. Surface winds greater than 50 knots, 3/4-inch hail
c. Surface winds greater than 50 MPH, 3/4-inch hail
d. Surface winds greater than 50 knots, 1-inch hail

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10. What is the abbreviation for a tornado in a PIREP (pilot report)?
a. TDO
b. TNO
c. FC
d. FC+

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11. Bonus judgment question: Based on the cloud formation in the accompanying picture, what would you do if you were considering flight in an aircraft the size of a speck of dust to any thunderstorm?

a. Take off and fly toward the cloud for a better picture.
b. Take off and fly west of the cloud.
c. Take off and hope the line of CUs doesn't return.
d. Not take off.

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