Meterology Flashcards
(109 cards)
1
Q
What does the atmosphere consist of?
A
78% Nitrogen
21% Oxygen
<1% carbon dioxide
2
Q
How do you describe “station pressure” for an aerodrome?
A
The weight of air above the airport (NOT with ISA or MSL).
3
Q
Flying through cloud after accumulating moderate icing, you begin to see ice crystals in cloud. Icing conditions will:
A
Improve.
4
Q
How does the liquid water content in layered-type clouds change by altitude?
A
Icing becomes severe near the tops of these clouds where the temperature is just barely below freezing.
5
Q
In a layered-type cloud, what temperature range would give you the most severe icing conditions?
A
0 to -15.
6
Q
What is the main difference between icing in layered cloud vs icing in cumulus clouds?
A
Cumulus clouds will have a more intense icing icing over a vertical extent.
7
Q
What type of icing would you get flying through a cumulus cloud and at what catch rate?
A
Clear ice & a high catch rate.
8
Q
What vapor/droplet conditions are found in the lower section of a cumulus cloud?
A
Large supercooled water droplets! CLEAR ICING.
9
Q
Severe icing in towering cumulus clouds can be found at temperatures as low as:
A
-25 degrees.
10
Q
Flying through (towards) a winter warm front, what will you encounter at low level and at high level?
A
Low level: snow, ice pellets, freezing rain, then rain (on the other side of the frontal surface)
High level: snow, freezing rain, rain (on the other side of the frontal surface)
11
Q
Where is a “roll cloud” usually on a thunderstorm:
A
On the LEADING EDGE of a thunderstorm.
12
Q
What is the first sign that a thunderstorm is in the dissipation stage?
A
Large downdrafts near the centre of the cell.
13
Q
What temperature rage is best for lightning?
A
-5 to +5.
14
Q
Where is the greatest amount of turbulence found at a thunderstorm?
A
In the middle to the upper regions of the cell.
15
Q
What precipitation gives off the strongest radar echoes?
A
Wet hail
16
Q
what type of precipitation gives the strongest weather radar returns?
A
Wet hail.
17
Q
What does a “hook” or “finger” on radar indicate?
A
Hail and turbulence.
18
Q
What does a dashed orange line indicate on a GFA:
A
An area of obstruction to vision not associated with precipitation. (smoke, smog, haze)
19
Q
When are GFA winds posted?
A
When wind is 20kts or stronger, or if there is a gust factor of more than 30kts.
20
Q
What should a pilot be aware of when using a surface weather map for IFR flight?
A
It shows condition that existed 2 to 3 hours before the weather map was issued. Be aware that the weather has moved!
It shows the past. VERY IMPORTANT WITH SURFACE ANALYSIS CHARTS! Issued 2 or 3 hours AFTER observation.
21
Q
Surface pressure patterns can be considered from:
A
3,000ft
22
Q
What does OCNL EMBD CB signify?
A
Embedded thunderstorms with little or no separation.
23
Q
What does FRQ CB signify?
A
Area of thunderstorms with coverage of more than 75%.
24
Q
Under what circumstances is RVR posted in a METAR:
A
If the prevailing visibility is 1SM or less AND/OR the RVR is 6000ft or less.
25
What is a TEMPO?
TEMPO is a fluctuation that are expected to last less than 1 hour in duration and are not going to cover more than half of the forecasted period.
26
What are the unorganized cloud formations?
SKC, FEW, SCT.
27
Absolute instability:
ELR > SALR/DALR
28
Conditional stability:
DLAR >ELR > SALR
If its unsaturated, its stable.
If its saturated, its unstable.
29
Absolute stability:
ELR < SALR/DALR
30
To determine stability of the air, you must compare:
The lapse rate between the rising air and the non-rising.
31
What is mean sea level pressure?
Pressure at mean sea level, based upon an average temperature over the last 12 hours. Also assumes standard lapse rate of 1.98 degrees per 1000ft.
Used for surface pressure charts.
32
```
Station pressure (actual weight of air above station)
Mean Sea level pressure (based upon average temperature over last 12 hours, used for surface weather analysis charts)
Altimeter setting (station pressure reduced to mean sea level using standard atmospheric conditions)
```
dd
33
What is station pressure?
The actual weight of air above station.
34
What is an altimeter setting?
It is station pressure reduced to mean sea level using standard atmospheric conditions.
Station, to MSL, to standard atmosphere
35
What is a process that causes the dewpoint spread to reach zero:
TWO WAYS:
1. Cooling the atmosphere (by a cooling process like expansional cooling) to the dewpoint
2. Adding moisture content to the atmosphere; i.e. raising the dewpoint temperature to the OAT
36
What is radiation fog?
Must be clear skies and 5/10kmh winds during the night for it to form.
If there are no winds, dew or frost will form.
When the ground is cooled from the night with moist air, as the sun rises, it mixes the cool air and creates radiation fog.
Occurs in valleys (RADIATIOR SPRINGS)
37
What is the main difference between radiation fog and advection fog?
Radiation fog is restricted to only occuring over land, whereas advection fog can form over land and sea.
38
What is advection fog?
Forms when a warm, moist air mass travels over a colder land mass or body of water.
39
What is advection fog?
Forms when a warm. moist air mass travels over a colder land mass or body of water.
40
What is steam fog?
Forms when water vapor is added to an air mass.
41
What is frontal fog?
Frontal fog forms ahead of a WARM FRONT within 50 to 100 NM ahead of it.
ADVECTION FOG WILL FORM after the passage of a warm front! (warm air, cool ground)
42
What defines an air mass:
Large section of the troposphere with uniform properties of temperature and moisture in the HORIZONTAL.
43
Continental arctic (cA):
Originates over the arctic with snow and ice; very cold and dry properties. VERY STABLE because of cooling from below.
In Winter:
Flows south over prairies where temperatures are mild; route is generally cold and dry, so it slams those zones with cold temperatures.
Over the Great Lakes:
Cold air flows over warm Great Lakes, heating from below = unstable = cloud and snow showers
In Summer:
Becomes Maritime Arctic! the "cA" does not affect North America in the summer months.
DEFINITION: Dry, stable, very low tropopause
44
Maritime Arctic (mA):
Travels over a mix of frozen and warm lakes on its way down. The warming promotes unstable conditions during the day and stable during the night.
During Spring and early Summer:
Changes the Continental Arctic air mass into Maritime Arctic air mass.
During Winter:
Arctic air over the west side of Canada moves over the warm Pacific Ocean, which makes it moist AND heating from below = unstable. This is why it rains all the time in Vancouver.
DEFINITION: Moist, cold, unstable, lower level tropopause
45
Maritime Polar (mP):
More stable than mA!
During Winter:
This air mass travels much longer over the Pacific Ocean, picking up more moisture and matches the waters' temperature.
During Summer:
the Continental Arctic air mass retreats, and the mP fills in the gap. cA becomes mA and mP during summer months.
DEFINITION: moist, cool, stable/unstable, medium level tropopause
46
Maritime Tropical(mT):
Is always a moist air mass and is usually warm.
During Winter:
Rarely reaches north of the Great Lakes. If it does, it will be pushed aloft by frontal lift and create an unstable condition causing HEAVY precipitation like heavy snow, freezing rain, ice. If it reaches the surface of Canada, it creates large fog banks over the Maritimes and Newfoundland.
```
During Summer:
If this (M O I S T) air mass is heated from below, it will create substantial thunderstorms and rain.
```
SUMMARY: moist, hot, unstable, high tropopause (like an ex)
47
What air masses affect Canada the most during the Winter months?
Continental arctic, maritime arctic. (cA, mA)
48
Which cold fronts are most common during the Summer months in Canada?
Maritime arctic (mA), Maritime polar (mP)
49
What are the three frontal systems that affect Canada?
Arctic front
Maritime front
Polar front
AMP
50
How will the barometric pressure be affects with the passage of a warm front?
Pressure will fall quickly and either stay or gradually rise slowly.
51
How will the barometric pressure be affects with the passage of a cold front?
Will be a drop in pressure then a very rapid rise in pressure after the cold front has passed.
52
Three conditions for thunderstorm development:
1. Unstable air mass to high levels
2. High relative humidity
3. Some lifting agency to initiate the process
53
What stage of a thunderstorm produces large downbursts?
The mature stage; when water droplets can no longer be lifted (developed) it all shoot down.
54
What are the two main effects of icing:
Roll upset
Tail plane stall
55
What is roll upset? What is it associated with?
Caused by airflow separation on ailerons; an uncommanded roll is imminent.
Associated when flying through icing condiitons where water sroplets flow back behind boot coverage and freezes to the surface.
56
Symptoms of roll upset:
Sloppy or abnormal aileron control forces when the autopilot is off.
57
What is a tail plane stall? What is it associated with?
Occurs hen the critical angle of attack is reached, leads to a rapid pitch-down. Using flaps will aggravate the stall.
Associated with icing in landing configuration or a nose-down pitching manouvre.
58
Symptom of tail plane stall:
Abnormal elevator control forces
Loss of elevator effectiveness
Sudden change in elevator forces
59
How many oktas is covered by a broken layer?
5 to 7 oktas
60
How many oktas is covered by a broken layer?
5 to 7 oktas
61
Convective cloud types and coverages:
ISOL - Less than 25% or less
OCNL - Between 26-50%
FRQ - More than >50%
62
Non-convective cloud and precip types:
LCL - 25% or less
PTCHY - 26-50%
XTNSV - >50%
63
What is "holdover" time?
Begins when the FINAL application of deicing/anti-icing fluid BEGINS, and expires when deicing/anti/icing fluid loses its effectiveness.
64
When flying through a colf front, a heading correction to the ___ is required.
Right.
65
What is an isotach?
A line joining areas of equal wind speed.
66
Weather radar operates in ______ radar and in the _____ frequency band.
Primary radar & SHF.
67
What does 00000KT mean on a TAF?
Winds are calm.
68
How do you calculate freeing level?
69
What does CCC mean on a GFA?
Third correction code for corrected airport.
70
Order of reflectivity of precipitation on a weather radar (biggest to smallest):
- Wet hail
- Rain
- Wet snow
- dry hail
- dry snow
71
When flying through moderate rain, the most important key to a more effective radar display is:
Use of the tilt control!
72
A sig wx chart is valid for:
6 hours.
73
Isobars on a chart are spaces out by ___ hectopascals.
4 hectopascal intervals.
74
What factors can be used to determine the position of a surface front?
Temperature
Dewpoint
Pressure
Wind
75
After passsage of a cold front, surface wind will always _____.
Veer and increase.
76
After passage of a cold front, surface wind will always _____.
Veer and increase.
77
As a Maritime Tropical air mass moves over the Great Lakes in spring and early summer, expect _____ to occur.
Continuous rain.
78
Large supercooled water droplets are commonly found in:
Lower levels of cumulous type clouds.
79
Transition from cumulus stage to mature stage of a thunderstorm is indicated by waht?
Appearance of rainfall at the surface.
80
In regards to airborne weather radar systems, what is attenuation? What causes it?
Attenuation is a significant reduction in cell detection capabilities.
The presence of large amounts of precipitation between radar antenna and target storm can cause these errors.
81
In regards to airborne weather radar systems, what is attenuation? What causes it?
It is the loss of effectiveness to
82
What processes heat the atmosphere?
1. Radiation
2. Convection
3. Advection
4. Subsidence (compression)
83
How does the pressure gradient force flow in regards to isobars between a low and a high pressure?
It is perpendicular to the isbars.
84
Which way does the coriolis effect deflect the wind direction?
To the right.
85
What is a microburst?
Less than 2 NM and less than 5 minutes.
86
What is a macroburst?
Greater than 2 NM and lasts 5 to 20 minutes.
87
When flying in locations where thunderstorms are present, avoid them by:
At least 3 NM on the upwind side and 10 NM on the downwind side.
88
Rule of thumb regarding thunderstorms and freezing level:
When flying above freezing level, avoid thunderstorms by 10 NM
When flying below freezing level, avoid thunderstorms by 5 NM
89
______ is a good indicator of strong updrafts within cumulous clouds.
Droplet size.
90
What is the most reflective signature on a weather radar?
1. Wet hail
2. Rain
3. Wet snow
4. Dry hail
5. dry snow
91
What does the gain control do?
Adjusts radar sensitivity.
At lower levels, there will be a lot of red spots because its all wet precipitation.
At high levels, the precipitation is frozen, and may need to be cranked up.
92
How can fog be formed?
Cooling the atmosphere to the dew point
Adding moisture to the air (increasing the dew point)
93
Fontal fog typically forms _____ ahead of the front.
within 50 NM to 100 NM.
94
Icing on an airframe could reduce lift by ___% and increase drag by ___%
30% and 40%
95
Temperature range for clear ice:
0 to -10 degrees.
96
Temperature range for rime ice:
0- and -20 degrees.
97
Temperature range for mixed icing:
0 to -15 degrees.
98
What type of cloud does clear, rime and mixed icing occur in individually?
Clear: cumulus and freezing rain
Rime: stratus (layered)
Mixed: Cumulus
99
What is an air mass?
Uniform in temperature and pressure IN THE HORIZONTAL.
100
How long can TAFs be valid for?
up to 30 hours.
101
What radius does a TAF make the forecast for?
Flight operations within 5 NM.
102
GFA altitude shows weather below:
24,000ft
103
What are the speeds regarding a quasi-stationary front?
Moving at less than 5kts.
104
How often are surfacce analysis charts updated/posted?
4 times a day; 0000z, 0600z, 1200z, 1800z
105
When there is __, ___, and ___ reported in a GFA comment section, you can expect:
CB, TCU, ACC, expect moderate to severe turbulence OR icing in that area.
106
Define IFR (GFA):
Ceilings less than 1000' AGL
and/or
Visibility less than 3 SM
107
Define MVFR (GFA):
Ceiling between 1000' and 3000' AGL
and/or
Visibility between 3 and 5 SM
108
Define VFR (GFA):
Ceilings more than 3000' AGL
AND
Visibility more than 5 SM
109
Surface pressure charts altitude:
```
5,000 = 850mb
10,000 = 700mb
18,000 = 500mb
24,000 = 400mb
```
