Meteorology 2

Question 1

Station Pressure

Answer 1

Weight of column of air lying above an airport

Question 2

Altimeter Setting

Answer 2

• Station pressure + weight of column of air between ground and sea level
• Weight of imaginary column of air calculated using ICAO standard atmosphere

Question 2

Mean Sea Level Pressure

Answer 2

• Station pressure + weight of column of air between ground and sea level
• Weight of imaginary column of air calculated using average temperature over previous 12 hours

Question 3

Low Pressure Systems

Answer 3

• Cyclones
• Surround by high pressure
• Air rotates counter clockwise in northern hemisphere due to Coriolis effect
• Air converges into a low

Question 4

High Pressure Systems

Answer 4

• Anti-cyclones
• Surround by low pressure
• Air rotates clockwise in northern hemisphere due to Coriolis effect
• Air diverges from a high

Question 5

Coriolis Effect

Answer 5

• Atmosphere does not rotate at the same speed as the surface
• Apparent when air attempts to flow in a north south direction.

Question 6

Friction Effect

Answer 6

• Topographical features reduce wind speed at low level
• Only occurs up to 2000-3000 AGL

Question 7

Sea Breeze

Answer 7

• Sea to land
• During the day, the temperature of the land rises more quickly than the water

Question 8

Land Breeze

Answer 8

• Land to sea
• During the night, the land cools more quickly than the water

Question 9

Anabatic Wind

Answer 9

• Valley Breeze
• Occurs during the day when the sun warms the mountain sides
• Air in contact warms by conduction
• This air is less dense and rises up the mountain

Question 10

Katabatic Wind

Answer 10

• Usually occurs during night
• Mountain sides cool quickly
• Air in contact becomes cold through conduction
• Cold air sinks to the valley below
• Can occur during the day due to snow covered slopes reflecting sunlight

Question 11

Causes of Wind Shear

Answer 11

• Nocturnal Inversions can produce shear zones usually at 1000 AGL
• Thunderstorms

Question 12

Low Level Jet Stream

Answer 12

• Sheet of strong winds
• Dissipates as daytime heating eliminates inversion

Question 13

Air Masses

Answer 13

• large section of troposphere with uniform properties of temperature and moisture
• takes properties from surface over what it is formed

Question 14

Cold Front Weather

Answer 14

Determined by the moisture content and stability of the warm air mass

Question 15

Signs of Cold Front Passage

Answer 15

• Decrease in temp
• Wind veer and increase speed
• Falling then rising

Question 16

Warm Front Weather

Answer 16

Determined by the moisture content and stability of the warm air mass

Question 17

Signs of Warm Front Passage

Answer 17

• Temperature will increase
• Wind will veer gradually
• Visibility generally poorer

Question 18

Frontal Depressions

Answer 18

• Two air masses flowing parallel to a front
• Quasi-stationary
• Cold air neither advancing nor retreating
• Wave is created due to atmospheric disturbance
• Cyclonic flow is created and low pressure system develops, along with cold and warm fronts
• Cold air moves faster and undercuts the warm air, forming an occluded front
• System weakens and then becomes a stationary front again

Question 19

Occlusions

Answer 19

Cold front catches warm front, forcing the warm air up, called a TROWAL

Question 20

Upper Fronts

Answer 20

• Narrow transition zone between two air masses where the temp difference does not exist at the the surface
• Sometimes a front doesn’t come right down to the surface

Question 21

Causes of Upper Fronts

Answer 21

• Very cold air is trapped below two warmer air masses, could have a warm or cold front above it
• A very shallow warm or cold front
• Daytime heating equalizes the temperature of two air masses at a front

Question 22

Aircraft Icing

Answer 22

Occurs when supercooled water droplets freeze on contact with a cold aircraft

Question 23

Requirements for Icing

Answer 23

• Visible moisture
• Below freezing temperatures
• must fly through cloud below the freezing level or through freezing precipitation

Question 24

Clear Ice

Answer 24

- Slow freezing - High temperature - Harder to remove - Smooth, not as diminishing

Question 25

Rime Ice

Answer 25

- Rapid freezing - Low Temperature - Easier to remove - Brittle, very diminishing

Question 26

Collection Efficiency

Answer 26

- Thin airfoil (horizontal stabilizer) - High aircraft speed - Large droplets

Question 27

Trace Icing

Answer 27

Not hazardous unless encountered for over 1 hour

Question 28

Light Icing

Answer 28

May be a problem if conditions persist (under 1 hour)

Question 29

Moderate Icing

Answer 29

Short encounters become potentially hazardous, anti-icing or diversion required

Question 30

Severe

Answer 30

Anti-icing doesn't work, diversion necessary

Question 31

Ice of a Medium Grit Sandpaper

Answer 31

- Lift decreases 30% - Drag increases 40%

Question 32

Tail-Plane Stall

Answer 32

- Tail stalls first due to high catch rate - Don't use flaps, increase speed

Question 33

Icing in Cloud - Layer Cloud

Answer 33

- Freezing level to -5ºC - Tend to have rime ice

Question 34

Icing in Cloud - Vertical Cloud

Answer 34

- Freezing level to -15ºC - Tend to have clear ice

Question 35

Icing in Cloud - TCU or CB

Answer 35

Freezing level may be up to -25ºC

Question 36

Frost

Answer 36

- Sublimation of water vapour directly onto the aircraft - Requires a cold, clear night, or a rapid descent in below freezing temperatures (hoar frost)

Question 37

Frozen Dew

Answer 37

- Water vapour condenses on the aircraft - Water freezes as the temperature drops

Question 38

Cold soaking

Answer 38

- Warm wings are filled with cold fuel - Air adjacent to underside of wing cools, condensation or sublimation occurs - May takeoff if POH procedures are followed

Question 39

Turbulence Causes

Answer 39

- Windshear - Frontal Air - Hot air - Surface Texture

Question 40

Turbulence Classification

Answer 40

- Occasional (<1/3) - Intermittent (1/3 to 2/3) - Continuous (>2/3)