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CPL Met > Met Lesson 3 > Flashcards

Met Lesson 3 Flashcards

(69 cards)

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1
Q

Air Mass Source Region Types

A

Sea/land: maritime/continental

By latitude: tropical/polar

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2
Q

4 Air Mass Source Regions

A 
Tropical maritime (Tm)
Tropical continental (Tc)
Polar maritime (Pm)
Polar continental (Pc)
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3
Q

Source Regions Affecting the Characteristics of Air Masses

A

Air takes on the characteristics of the surface its over
Continental air masses lose moisture due to contact with the land
Air within Polar cell = polar air
All other air cells are comprised of tropical air

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4
Q

A Front

A

The boundary between two different temperature air masses

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5
Q

Cold Fronts

A

Warm air forced to rise over heavier cold air
Cold, dense air will wedge in under the warmer air
Very little mixing due to the different densities

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6
Q

Weather in an Approaching Cold Front

A 
Reducing pressure (rising air particles)
Northwest winds
Cumulus clouds and showers
Cb if the warm air is conditionally unstable
Altocumulus and altostratus cloud
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7
Q

Ahead of the Cold Front

A

Gusts and squalls
Fast moving low cloud
Turbulence
Possible squall line

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8
Q

Passing Cold Front

A

Increasing pressure
Northwest wind backing to Southwest winds
Reducing temperature
Cumulus/towering cumulus/small cumulonimbus as frontal inversion increases with height

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9
Q

Warm Front

A

Warm less dense air will gradually slope up against the colder and more dense air

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10
Q

Weather Associated with a Warm Front

A

If the warm air is stable: Cirrus and cirrostratus creating the halo effect
Cloud becomes thicker and lower with passing front
Altocumulus, altostratus, nimbostratus
Heavy and continuous rain
If the warm air is less stable more cumulus will develop

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11
Q

Weather Associated with a Passing Warm Front

A

Warm air advancing over a cold ground creates a stable environment and the cloud will clear rapidly
Fair weather

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12
Q

Wave Depressions

A

A low pressure system is formed on the tip of the cold front as the warm air is being lifted by the cold air
The cold air swings (veers) around and catches up with the warm front because the colder air is heavier
Once it catches up it produces an occluded front

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13
Q

Occluded Front

A

Fast moving cold front catches up with the slower moving warmer air
The cold air forces the warm front upwards

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14
Q

Embedded Cumulonimbus

A

Thunderstorm obscured by other types of cloud

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15
Q

Stationary Front

A

When two air mass systems become stationary and there is no resultant movement present
When some upper air disturbance occurs the stationary system becomes displaced

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16
Q

Visibility

A

The greatest horizontal distance at which a person can identify a dark object with normal eyesight
May be specified for each direction and reported in m or km

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17
Q

Visibility Obscurations

A 
Reduce in-flight visibility
Moisture - precipitation/fog/cloud/etc
Smoke
Pollution
Dust/sand
Sun - glare, light/darkness
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18
Q

Reported Visibility

A

Visibility from the ground reported by an accredited observer on the ground

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19
Q

Flight Visibility

A

Horizontal visibility as observed by the pilot from the cockpit when in flight

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20
Q

Slant Visibility

A

The air to ground visibility observed by the pilot from the cockpit when in flight

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21
Q

Night and Day Visibility

A

Night visibility is normally better than daylight visibility

Daylight visibility is the worst at dawn and dusk

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22
Q

Vertical Visibility

A

Air to ground visibility when above the object (ft)

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23
Q

Runway Visual Range

A

Maximum distance that the runway can be seen from the average eye level of the pilot at touchdown
Measured with electronic instruments installed next to an ILS equipped runway

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24
Q

Dew

A

Water vapour condensates onto objects in the form of dew when sufficient moisture is available during overnight cooling
Normally after a clear night with sufficient moisture

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25
Frost
The temperature of the ground is below 0°C Frozen dew Disrupts laminar airflow over the wing, loss in lift and increase in drag Cooling effects on the wing due to acceleration
26
Conditions Required for Icing
Visible moisture, near freezing temperatures, super cooled water droplets (subzero water in liquid state) Freezing temperatures Freezing airframe temperature Resistance to freezing due to spherical shape Any disturbance/shock to change the shape of the droplet, allows the release of latent heat and freezing
27
Hoar Frost
Nighttime cooling close to the ground Deposits of ice crystals Doesn't require super cooled water droplets for formation
28
Affects of Hoar Frost on Aircraft
Negatively affects the aerodynamics of the wings May occur when aircraft cruising in cold altitudes Airframe cools down - cold soaking On descent, the aircraft enters warmer air and turns to frost via deposition
29
Rime or Clear Ice
Usually both present, however one type tends to predominate Type depends upon the supercooled water droplet size and the type of cloud Larger droplets require a larger cloud as strong up draughts are required
30
Catch Efficiency
A thicker wing will catch more water | Thicker is better
31
Clear Ice
0°C to -15°C Large drops of freezing rain The drop flows backwards on the surface and spreads before it freezes as it loses more latent heat in warmer conditions No air is trapped inside the ice making it transparent and difficult to see
32
Clouds Producing Clear Ice
Cumuliform Nimbostratus cloud Thick altostratus
33
Rime Ice
-10°C to -20°C Small supercooled water droplets Opaque in colour due to air pockets within the droplets
34
Clouds Producing Rime Ice
Altostratus Altocumulus Cumulus tops Stratiform above the freezing level
35
Surface Areas Mostly Affected by Icing
``` Wing leading edges Windscreens Tail section Engine/propellers/engine intakes Antennae ```
36
Affects of Icing on an Aircraft
``` Increase in drag Increase in weight Decrease in lift Decrease in thrust Blocked pitot tubes Decreased visibility May restrict control surfaces Reduced breaking action on the runway ```
37
Icing Due to Warm Fronts
Rain falling from the warmer air through the colder air may become severe clear ice Flying into a lowering cloud base due to a warm front may lure you into severe icing conditions
38
Differences from Fog and Cloud
``` Height at which they occur Formation process (fog from conduction) ```
39
Fog and Mist
Natural visibility reducing phenomenas just above the ground level
40
Fog
Horizontal visibility < 1000m
41
Mist
Horizontal visibility => 1000m
42
Conditions Required for Radiation Fog
Light winds < 5kts Clear skies at night (max terrestrial radiation) High relative humidity (more humid = more likely for dew point to be reached)
43
The Clearing of Radiation Fog
Winds > 5kts An increase in solar heating A decrease in humidity
44
The Effects of Solar Heating on Radiation Fog
Initially after sunrise the fog thickens due to the increased mixing by solar heating (also the coldest time of the day) Thin and evaporates from below as the ground surface heats up
45
Advection Fog
Warm humid air passing horizontally over a cold surface May form at any time of day or night May persist for days Eg. Warm humid air from tropical oceans over polar surfaces
46
Dissipation of Advection Fog
Wind > 15kts Reduced humidity due to deposition of water droplets on vegetation Change in wind direction
47
Fog Due to Mixing
Radiation for = 2 - 5kts (light wind) Small or no difference between OAT and dew point Advection fog = 10 - 15kts (stronger wind
48
Frontal Fog
Cloud forms on the frontal boundary of the warm front | Warm rain causes the colder air below to become saturated
49
Steam Fog
Cold moist air flows over warmer water | Evaporation from the water surface causes the air to become saturated
50
Dangers of Fog and Haze
Slant visibility obscurations | Poor visibility
51
Requirements for the Formation of Thunderstorms
1. An unstable atmosphere (ELR > 3°C/1000ft) or conditionally unstable 2. An abundance of moisture 3. Lifting mechanism (convection, orographic lifting, frontal, convergence)
52
Stages of a Thunderstorm
1. Cumulus/growing/developing stage 2. Mature stage 3. Dissipating stage
53
Cumulus Stage
Strong up draughts | No precipitation
54
Mature Stage
``` First gust Lightning Wind change 180° = runway change Strong up and down draughts 20 - 30 mins Rain showers begin ```
55
Dissipating Stage
Continuous precipitation until the cloud is empty (rains out) Storm moves away in the direction of the anvil
56
Thunderstorm Hazards
``` Lightning strike (compass swing) Static electricity Gust/dust storms Turbulence and windshear Temporary affects on night vision due to lightning flashes Poor visibility Severe airframe icing Aquaplaning Hail Excessive cockpit noise ```
57
Down Draughts Due to Cloud
Strong underneath the clouds Virga Down draughts due to an air mass becoming heavier and more dense than the warmer air
58
Microbursts
Often associated with cumulonimbus clouds Very strong downburst with a diameter of 4km Avoid cumulonimbus by 20nm Airflow spreads out near the ground Severe windshear
59
Tropical Cyclones
Small intense low pressure systems over warm ocean | Generally occur in the Southern hemisphere summer: November to April
60
Formation Requirements for Tropical Cyclones
Narrow band of latitude in the Southern Hemisphere (5° - 15° South) In this area the oceans are warm and the coriolis force is strong enough for rotation When the cyclone is too close to the equator it has less of a spin as the coriolis force is weaker
61
The 4 Stages of A Tropical Cylone
1. Formative 2. Immature 3. Mature 4. Decaying
62
Formative Stage of a Tropical Cyclone
Eye forming Humid air pulled into the low and forced to rise via convergence Air cools adiabatically: dew point reached and cloud forms Condensation releases latent heat, causing faster rising due to an increase in temperature < 1000hPa
63
Immature Stage of a Tropical cyclone
Strong winds Pressure gradient steepens as pressure beneath becomes lower Sucks more air in and the cycle continues Winds light and variable inside the eye Strong winds > 120kts around the eye with CB's
64
Mature Stage of a Tropical Thunderstorm
Surface pressure about 950hPa remaining constant Strongest wind in the left forward quadrant due to steepest pressure gradient Nimbostratus with spiral bands of cumulus and cumulonimbus, cirrus on top Heavy rain clouds around the eye Cloud-free eye as the temp is above dew point due to the release of latent heat
65
Decaying Stage of a Tropical Thunderstorm
Rain depression Die-out or become rain depressions once they move inland or move towards the colder pole (water temp < 26°C) or beyond 15°S Due to reduced up draughts and water vapour supply Colder and drier air over the ground (increased surface friction) Widespread rain may continue for several days
66
Tornados in North America
Great plains are exposed to cold and warm air Massive convergence with sharply inclined isobars Rotating twist due to differing winds that becomes a spiral
67
Tornado
Massive super cell thunderstorm <300m in diameter Wind speeds up to 200kts Central pressure rotating funnel 50hPa lower than the surrounding air: buildings explode as the tornado passes over
68
Funnel Cloud
Doesn't touch the ground
69
Waterspouts
Touching the water surface and sucking water up

CPL Met (4 decks)

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