Weather (11-16% of test)

Question 1

Weather reports and forecasts can come from a FSS weather specialist. What is FSS?

Answer 1

Flight
Service
Station

Question 2

What is the relation of “density altitude” and how does it effect aircraft?

Answer 2

Density altitude is the pressure of the atmosphere. As air pressure decreases, “density altitude” increases. In other words, “density altitude” increases with higher altitude.
A higher “density altitude” has lower atmospheric pressure which:
- Increases takeoff and landing distances because more air speed is needed around the air foil of a wing
- Decreases climb rates due to higher speeds needed for lift

Question 3

What are the weather qualities of high pressure areas? (3)

Answer 3

• Dry air
• Descending air
• Good weather

Question 4

What are the weather qualities of low pressure areas? (4)

Answer 4

Low pressure generally means:

• “bad weather”
• cloudiness
• precipitation (wet air)
• ascending air

Question 5

What are “convective currents”, what makes them, and how do they effect flight?

Answer 5

1) Convective currents are local air patterns close to the earth that change the direction of air flow.
2) Convective currents are caused by uneven solar heating of the ground. Barren land absorbs solar energy quickly this gives off more heat. Vegetated land and areas of waters absorbs solar energy slowly. This uneven heating causes currents of air movement.
3) Convective currents cause bumpy flights, turbulent air, updrafts over barren land, and downdrafts over water and vegetation.

Question 6

Is air flow more turbulent on the Windward (side where wind is coming from)
or
Leeward side (backside of terrain relative to wind direction)?

Answer 6

Leeward

Question 7

1) What is wind shear?
2) Why is it bad for aircraft?
3) What weather is low level windshear commonly associated with?
4) What is the most severe type of low – level windshear and ?

Answer 7

1) Sudden drastic wind speed changes.
Windshear is a sudden, drastic change in wind speed and/or direction over a very small area.
2) Updrafts, Downdrafts, and quick changes wind direction
Windshear can subject an aircraft to violent updrafts and downdrafts, as well as abrupt changes to the horizontal movement of the aircraft. A tailwind can quickly change into a headwind or vice versa.
3) Fronts, Storms, High winds
Watch out for frontal systems, thunderstorms, temperature inversions, and strong upper-level winds greater than 25 kn.
4) A Microburst.
“Microburst”, is associated with convective precipitation into a dry air and cloudbase. 

Question 8

1) What is “dew point”?

2) Why is it important?

Answer 8

1) Temperature that air condenses moisture. Dew point, given in degrees, is the temperature at which the air can hold no more moisture and starts to condense.
2) Frost disrupts air flow over a wing and drastically reduced the production lift and increase drag. When air temps fall to the dew point fog, dew, frost, clouds, rain, or snow happens. If the temperature is below freezing = frost.
An aircraft must be thoroughly clean and free of frost prior to beginning the flight.

Question 9

What are the 4 typical classifications of LOW cloud types?

Answer 9

Stratus, stratocumulus, nimbostratus, & fog

Strat means low: strat…, strat…c, n…strat, & fog

Question 10

What type of clouds causes moderate icing?

Answer 10

Altostratus (mid-altitude long flat clouds)

Question 11

1) What do cumulonimbus clouds cause?

2) What are they known as to pilots?

Answer 11

1) Bag Weather
Cumulonimbus clouds contain large amounts of moisture unstable air and usually produce hazardous weather phenomena, Such as lightning, hale, tornadoes, gusty winds, and windshear.

2) Most dangerous
To pilots, the cumulonimbus cloud is perhaps the most dangerous cloud types.

Question 12

What are some conditions that define a stable air mass?

Air, Clouds, Precip., Visibility

Answer 12

• Smooth air (not rough turbulence)
• Stratiform thin clouds (not cumuliform) with no vertical development
• CONTINUOUS precipitation (not showery)
• Poor (to moderate) visibility (not good)

Question 13

What are some of the conditions that define an UNstable air mass? (4)

(Air, Clouds, Precip., Visibility)

Answer 13

• Rough turbulence (not Smooth air) or varying conditions
• Cumuliform (Cumulus) clouds (not Stratiform) that build vertically is size
• Showery precipitation (not Continuous) not consistent
• Good visibility (not poor to moderate) caused by varying wind direction

Question 14

1) What are the visual rules the remote PIC must adhere to before flight? (3)
2) What is the best way is to obtain local aviation report on visibility?

Answer 14

• 3 statute miles (SM) visibility between sUAS and control station
• 500 feet below clouds
• 2,000 feet horizontally from all clouds
• METAR (or TAF (if in controlled airspace)

Question 15

Per the FAA what is the official FAA forecast of aviation activity for U.S. airports?

Answer 15

Terminal Area Forecast (TAF)

• Cover the area 5 statue miles surrounding the airport
• Only updated 4 times a day

Question 16

What are the 5 parts of a Terminal aerodrome forecast (TAF) in order?

Answer 16

1) Type of Report
2) Station Identifier
3) Date & Time of Origin
4) Valid Period Start Date Time and End Date and Time
5) Forecast Condition: Wind, Visibility, Weather, Clouds. The repeating with each from = “FM”(2 digit date)(4 digit time)

Question 17

When should standard, abbreviated, or outlook briefings be requested (looked up)?

Answer 17

Standard - Prior to flight
Abbreviated - If flight is delayed
Outlook - Departure is 6 hours away

Question 18

What is sublimation?

Answer 18

Sublimation is the process that occurs when ice, is turned into water vapor.

Question 19

Describe “Radiation Fog”

Answer 19

Ground warm (radiating), Air cool and Wind calm. 
When sun heats ground all day, air is calm, then cool evening air come in. 
Radiation fog is a very common type of fog throughout the United States. It is most prevalent during the fall and winter. It forms overnight as the air near the ground cools and stabilizes. When this cooling causes the air to reach saturation, fog will form. Fog will first form at or near the surface, thickening as the air continues to cool. The layer of fog will also deepen overnight as the air above the initial fog layer also cools. As this air cools, the fog will extend upward.

Question 20

Describe “Advection Fog”.

Answer 20

Ground (water) cold, Air warm and moist, Wind do not have to be calm. (Beaches)
“Advection fog” forms as warmer, moist air moves over a cold ground.
The air is cooled to saturation by the cold from the ground below cooling the air above. Unlike radiation fog, advection fog may form under cloudy skies and with moderate to strong winds. Initial stability is relatively unimportant since low level cooling makes the air stable near the ground, allowing the fog to form. Once formed, it may move across the landscape, pushed by low level winds. Advection fog can last for several days and is most common in the U.S. on the West Coast.

Question 21

Describe “Upslope Fog”.

Answer 21

Upslope fog is formed when air flows upwards over rising terrain and is cooled to its saturation temperature.

Question 22

Describe “Steam Fog” or precipitation induced fog

Answer 22

Hot ground evaporated precipitation.
This typically happens during summertime in the ground has been heated by the sun all day and there is a slight shower precipitation that when it hits the hot ground immediately turns into steam.

Question 23

Describe cumulus low level clouds.

Answer 23

“Heap”

1) Cumulus: thick, white fluffy clouds that are scattered throughout the sky, building vertically.
2) Cumulonimbus: the Latin suffix “nimbus” means rain

Question 24

Describe stratus clouds.

Answer 24

Stratus = layer

Stratus clouds are typically dismal clouds that fill the sky with a layer of dark cover. 

Question 25

Describe cirrus clouds. 

Answer 25

• High level
• Classified as 20,000 feet and above. 
• Wispy and thin
• Indicate change in weather

Question 26

What is the 2nd most intense stage of a thunderstorm?

Answer 26

Mature Stage