Meteorology Flashcards
(255 cards)
1
Q
The primary source of all weather is the
A
Sun
2
Q
Areas of . . . . . pressure flow towards areas of . . . . . pressure. This movement of flowing air is known as . . . . .
A
High, low, wind
3
Q
Wind does not flow directly towards a low pressure system because of the
A
Coriolis force
4
Q
The primary cause of all changes in Earth’s weather is
a.changes in air pressure over the surface.
b.variation of solar energy at the surface.
c.movement of air masses from moist areas to dry areas.
d.none of the above.
A
B
5
Q
What is the atmosphere made up of?
A
78% nitrogen
21% oxygen
1% other gas, argon, water vapour and carbon dioxide
6
Q
What are the major layers of the atmosphere?
A
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
7
Q
Average height of troposphere?
Approximate height at poles and equator?
A
36,000 feet,
25,000 feet at poles
54,000 feet at equator
8
Q
What are the ISA specs?
A
15 c
29.92 in Hg
1013.25 mb
Standard atmosphere at sea level
9
Q
What does ISA +6 mean?
A
Temperature is 6 degrees warmer than standard temp
10
Q
The ozone layer is located in the
A
Stratosphere
11
Q
During cruise at FL200 the OAT is -35°C. The air mass therefore has an average temperature which is
a.5°C warmer than ISA.
b.20°C colder than ISA.
c.5°C colder than ISA.
d.10°C colder than ISA.
A
D
Standard temperature is 15°C at sea level.
Therefore with a lapse rate of approx 2°C /1 000 feet
20 x 2° = 40°
15° - 40° = -25°
Standard temp at FL200 would be -25°
12
Q
The feature that is associated with the Tropopause is
a.the absolute upper limit of cloud formation.
b.the abrupt change of lapse rate.
c.the absence of wind and turbulence.
d.none of the above.
A
B
13
Q
What is boyle’s law?
A
At a given pressure, warm air will take up a greater volume than cold air
14
Q
How far apart are standard isobars?
A
4 millibars/hectopascals
15
Q
How often are altimeter setting measurements taken?
What about msl measurements?
A
1 hour
12 hours
16
Q
Accuracy of altimeter setting varies with ___ from the station, especially if there is a strong ____ ____
A
Distance
Pressure gradient
17
Q
From hot to cold, you are being bold. What does this mean?
A
When flying from higher temperature to colder than standard temperature, the aircraft will be lower than indicated, causing possible terrain impact amongst other hazards
18
Q
The steeper the pressure gradient the ____ the wind.
A
Stronger
19
Q
High pressure areas are areas where the air is ____ (sinking/rising)
Is the temp higher or lower?
What is the general air movement?
Another name for high pressure system?
Type of weather associated with a high?
Does it move fast or slow
A
Sinking
Lower
Clockwise, outwards (diverging, descending)
Anticyclone
Fair weather, fewer clouds, good visibility, light winds, can remain for days and produce early morning fog
Typically slower moving systems
20
Q
Low pressure areas the air is ____ (rising/sinking)
Temp high or low?
General air movement?
Another name for low pressure system?
Type of weather expected with low?
Does it move fast or slow
A
Rising
High
Counterclockwise and inward (converging and ascending)
Cyclone
Cloudy weather, precipitation. Expect thunderstorms, rain, hail, snow, if there is a steep pressure gradient expect strong winds
Typically fast moving, summer 500 miles a day, winter 700 miles
21
Q
What is a trough?
What does it bring with it?
A
An elongated area of low pressure
Usually brings clouds, showers and wind shift
22
Q
What is a ridge?
What does it bring?
A
Area of elongated high pressure with low pressure on each side.
Usually brings fair weather
23
Q
What is a col?
What usually occurs within the area for weather?
A
Neutral region between two highs and two lows.
Usually unsettled weather, fog in winter and showers/thunderstorms in summer
24
Q
According to standard atmosphere the station pressure as measured by two stations in the same region but at different altitudes will be
a. the same.
b. higher as measured by the lower station.
c. higher as measured by the higher station.
d. 29.92 in Hg.
A
B
25
Flying over mountains with a temperature of 24ºC and the altimeter setting of 30.22 in Hg received from a nearby airfield. The terrain below the aircraft rises to 4 000 feet ASL, the true altitude when reaching 6 000 feet ASL will be
a.6 075 feet.
b.5 925 feet.
c.6 145 feet.
d.5 784 feet.
C
Pressure Altitude = 5 700 feet (29.92 - 30.22 = - 0.3 x 1 000 = - 300 + 6 000 feet =)
Temperature is 24ºC
Using the E6B correct altitude of 2 000 feet AGL (= IALT 6 000 - Elev 4 000), will get 2 145 feet and add to 4 000 feet ASL
26
What are the two main ways the atmosphere is heated?
Radiation, conduction
27
What is radiation heating?
The suns rays absorb into the earth and re-radiated creating infrared (terrestrial) radiation (longer wavelengths)
Water Vapor and carbon dioxide are very effective at absorption and heating surrounding atmosphere. remember atmosphere is always heated from below
28
What is conduction heating?
The layers of air that are in immediate contact with the surface are conduction heated. Air is a poor conductor thus conduction is only responsible for heating the layers closest to the surface
29
What is a diurnal variation?
What does the wind do in the day?
In the night?
As the sun rises vertical currents begin, and causes mixing between upper and lower air masses.
Winds usually increase and veer and become gusty.
At night winds decrease and back
30
What is a seasonal variation in regards to heating?
It has to do with the axial tilt of the earth, a shallow lighting angle gives less heating (winter) and more direct lighting angle gives more heating (summer)
31
What is convection?
Air near a warm surface is heated and due to its buoyancy it rises.
Summer afternoons produce the greatest convection.
Also forms in winter when cold air moves over open water.
32
What is advection?
Is a process that moves heat laterally. Cold air is carried to a warm area and heated from below . Warm air can also be carried over a cold surface (spring, warm air over snow makes fog)
33
What is latent heat?
Heat energy that is hidden in water vapour. Water takes away heat from surrounding area, rises, condenses, which will release heat that it absorbed near surface and heat the surrounding air
34
What is compression heat?
When a parcel of air sinks or subsides it is compressed by increasing air pressure of lower atmosphere, resulting in air warming up.
35
What is radiation cooling?
When sun sets the surface continues to radiate heat, causing ground to eventually cool and cool the surrounding air as well. Usually only affects the first few thousand feet altitude.
36
What is advection cooling?
Carries air from a warm area to over a cooler area.
37
What are the adiabatic cooling rates?
Same as lapse rate, 3 degrees dry 1.5 wet 2 standard
38
What is a temperature inversion?
Temp of atmosphere increases with an increase in altitude. Air is stable.
With a strong inversion you can expect wind shear
39
What is an isotherm?
Line of area with same temperature
40
What is melting?
When a solid becomes a liquid
41
What is evaporation?
When a liquid becomes a gas
42
What is condensation?
When a gas becomes a liquid
43
What is freezing?
When a liquid becomes a solid
44
What is deposition?
When a gas becomes a solid
45
What is sublimation?
When a solid becomes a gas
46
What is the dew point?
The temperature at a given pressure that the air must be cooled to in order to become 100% saturated.
47
What is relative humidity?
the amount of water vapour present in the air compared to the amount which the air could hold when saturated, given as a percentage.
48
Heating ____ the relative humidity.
Cooling ____ the relative humidity.
(Increases/decreases)
Heating decreases
Cooling increases
49
the amount of water vapour that an air mass can hold depends entirely upon its _____.
Temperature
50
The Environmental Lapse Rate is a theoretical measured change in temperature with increased height above the ground.
True or false?
False, it is the actual measured change
51
What is the standard adiabatic lapse rate?
1.98 degree change per 1,000 feet of elevation
52
What is the dry adiabatic lapse rate?
3 degrees per 1,000 feet
53
What is the saturated adiabatic lapse rate?
1.5 degrees per 1,000 feet
54
What is precipitation?
when the water droplets grow sufficiently in size and weight to overcome lifting agents such as fronts and updrafts.
55
Droplet size is often related to the strength of an updraft.
True or false?
True
56
What are the three main types of rainfall?
• Convergent and Cyclonic Rainfall
• Orographic or Relief Rainfall
• Convectional Rainfall
57
Where is Convergent and Cyclonic Rainfall found?
Warm front causes what type of rain?
Cold front causes what type of rain?
This form of rain is caused by the convergence of two air masses (fronts).
• Warm front rainfall tends to be steady.
• Cold front rainfall tends to be showery.
58
How is Orographic or Relief Rainfall formed?
• When warm moist air is forced to rise over an obstacle (mountain range) it cools.
• This cooling allows condensation to take place forming clouds and precipitation.
59
Rainfall totals will increase where mountains are parallel to the coast.
True or false?
True
60
What is a rain shadow?
an area of reduced rainfall on the leeward side of the mountains.
61
How is Convectional Rainfall formed?
When the ground surface is locally heated and the adjacent air expands and rises, convectional rainfall occurs. Ie cumulonimbus
62
How does snow form? This change of state is known as _____.
Snow forms under the same conditions as rain except that the dew point temperature is below freezing so the vapour goes straight to a solid
Deposition
63
When freezing rain freezes in the air it becomes?
Ice pellets
64
How do ice pellets form?
Occurs when there is a shallow layer aloft with above-freezing (2 to 4°C) temperatures and with a deep layer of below-freezing air based at the surface.
• As snow falls into the shallow warm layer, the snowflakes partially melt.
• If the depth of the warm air is great enough, then this can also melt further and turn into freezing rain.
• If there is a second layer of cold air below the warm air, (near the surface) then the partially melted snow or freezing rain can refreeze into ice pellets.
65
What type of precipitation is above ice pellets?
Freezing rain
66
How does freezing rain form?
Where is it commonly found?
What temperatures can large droplets freeze at?
Begins as rain and/or snow, but becomes all rain in the warm layer.
• The rain falls back into below-freezing air, but since the depth is shallow, the rain does not have time to freeze into ice pellets.
• This occurs when there is a deep layer aloft with above-freezing temperatures and with a shallow layer of below-freezing air at the surface.
- commonly found along a warm front, where a warm air mass overruns a cold air mass.
- large droplets can freeze at temps slightly below zero
-very tiny droplets can remain liquid up to -40c
67
Hail is ice which is larger than __ mm in diameter.
5mm
68
How does dew or frost occur?
The ground cools the air and this causes the moisture present to condense.
> If the dew point is above freezing then dew will form.
> If the dew point is below freezing then frost will form through deposition.
• Dew or frost usually form within 20 feet of the ground.
69
The best indication of relative humidity is
a.the amount of moisture in the air as a ratio of water vapour to air.
b.the temperature and dew point spread.
c.the dew point alone.
d.none of the above.
B
70
Given: Surface temperature 20°C
Dew point 5°C
Elevation 1 000 feet ASL
The expected cloud base is
a.5 000 feet ASL.
b.6 000 feet ASL.
c.10 000 feet ASL.
d.11 000 feet ASL.
B
Calculate Spread: Temp 20°C - Dew Point 5°C = 15°C / 3°C = 5 x 1 000 feet = 5 000 feet Cloud Base AGL
Cloud Base 5 000 feet + Elevation 1 000 feet = 6 000 feet Cloud Base ASL
71
Given: Surface temperature 18°C
Dew point 3°C
Elevation 523 feet ASL
The freezing level is at
a.2 000 feet AGL.
b.7 000 feet AGL.
c.2 523 feet AGL.
d.7 523 feet AGL.
B
Temp 18°C - DP 3°C = 15°C / 3°C = 5 x 1 000 = 5 000 feet AGL cloud base
Dew point 3°C / 1.5°C = 2 x 1 000 - 2 000 feet above cloud base + cloud base 5 000 = 7 000 feet AGL
72
What are some characteristics of stable air?
• Smooth flying
• Poor visibility
• Steady precipitation
• Layer cloud (Stratus)
• Ultimate - Fog
• Shallow lapse rate
• Inversion
• Warm air moving over cold air
73
What are some characteristics of unstable air?
• Bumpy flying
• Good visibility
• Showery precipitation
• Cumulus cloud (heap)
• Ultimate - Thunderstorm
• Steep lapse rate
• High temperature / dew point
74
How can unstable air form?
-Radiation heating during the day
-warm air moving into a region
-surface based cold advection
These will be enhanced if there is moist air near the ground and dry air aloft and the unstable air extends into higher levels
75
What are the 4 types of lapse rates?
• Steep Lapse Rate
• Shallow Lapse Rate
• Inversion
• Isothermal Layer
76
What is a steep lapse rate?
Stable or unstable?
Temperature decreases rapidly with altitude.
* A steep lapse rate is one that leads to instability.
77
What is an inversion?
Stable or unstable?
• The temperature increases with altitude.
• In this case the air is stable.
78
What is an isothermal layer?
Stable or unstable?
• The temperature does not change with altitude.
• In this case the air is stable.
79
What are the 4 methods of surface heating?
Radiation
Conduction
Advection
Convection
80
Explain how each of the 4 surface heating elements work.
Radiation- reflection of the earths rays
Conduction- warm air contacting cold air
Advection- horizontal movement of air
Convection- unequal surface heating
81
Explain briefly the following lifting processes:
Convection
Convergence
Mechanical turbulence
Orographic lift
Frontal lift
Convection- unequal surface heating
Convergence- excess air rises as pressure systems meet
Mech turbulence- surface friction
Orographic lift- air moving up hills (anabatic)
Frontal lift- advancing air being pushed up by cold air on the bottom
82
The ____ the dew point, the greater the amount of moisture the air contains.
(Higher/lower)
Higher
83
What is subsidence?
Subsidence is when air sinks, this results in compression and warming the air.
84
Not a source of unstable air conditions is
a.moist air near the ground is lifted by convection.
b.advection of warm air over the ground.
c.large scale rising of the air.
d.radiation cooling during the night.
D
85
After the passage of a cold front there is a nice VFR flying day with excellent visibility and a fair amount of cumulus clouds. Expected conditions are
a.very little convection due to a small spread between the temperature and dew point.
b.increased stability of the atmosphere since the front is already passed.
c.unknown as not enough information is given.
d.bumpy and turbulent flying conditions due to instability of the atmosphere with possible development of thunderstorms.
D
86
Heat can be transferred into the atmosphere by
a.radiation, conduction, advection, and convection.
b.rotation, consumption, invention, and convention.
c.radiation, precipitation, wind, and fronts.
d.none of the above.
A
87
Dissipation of clouds is related to
a.convection.
b.an increase pressure.
c.subsidence.
d.a decrease in temperature.
C
88
After an initial rise, a saturated parcel of air continues to rise but an unsaturated parcel of air remains cooler than the surrounding atmosphere. This is known as
a.conditional stability.
b.potential instability.
c.absolute stability.
d.absolute instability.
A
89
If the Sun was to burn out it would take us on Earth . . . . . to know about it.
8 minutes
90
The Sun's visible layers from outer to inner are the
a.Corona, Chromosphere and Photosphere.
b.Chromosphere, Photosphere and Corona.
c.Photosphere, Corona and Chromosphere.
d.Photosphere, Chromosphere and Corona.
A
91
The Sun's energy output operates on a . . . . . year cycle.
11
92
The Earth's axis is tilted at an angle of . . . . . with respect to the orbital motion.
23.5 degrees
93
When looking at Earth from the top of the north Pole, it rotates which direction?
Counterclockwise
94
The time of year when day or night is the longest is the
a.Solstice, occurring approximately June 21st and December 20th.
b.Equinox, occurring approximately June 21st and December 20th.
c.Solstice, occurring approximately March 21st and September 21st.
d.Equinox, occurring approximately March 21st and September 21st.
A
95
Identify the following as well as okta coverage.
What is SKC?
FEW
SCT
BKN
OVC
SKC- clear sky
FEW- 1-2/8 sky coverage
SCT - 3-4/8 sky coverage
BKN- 5/8 to less than 8/8 coverage
OVC- overcast, 8/8 coverage
96
VFR pilots are NOT permitted to fly above a ____ or ____ layer unless they have a ____ ____ rating
BKN or OVC
VFR OTT
97
Clouds are classified into four families based on their _____ and _____ ______.
Height, vertical development
98
What are the 4 cloud classes?
• High Clouds
• Middle Clouds
• Low Clouds
• Clouds with Vertical
Development
99
Low clouds, height level?
Some types?
Surface to 6500 ft agl
Stratus
Nimbostratus
Stratocumulus
Cumulus fractus
Status fractus
100
Middle level clouds height?
Some types?
6500-20,000 ft agl
Altostratus
Altocumulus
Altocumulus castellanus (turbulence)
101
High level cloud height?
Some types?
20-40,000 ft agl
Cirrus
Cirrostratus
Cirrocumulus
102
A ragged windswept appearance of the Cirrus Clouds is always an indication of very strong winds or jet streams.
True or false?
True
103
Clouds of vertical development types?
Cumulus
Towering cumulus
Cumulonimbus
Altocumulus castellanus
104
What do cumulus clouds indicate?
Do they indicate fair or poor weather?
Indicates the presence of significant vertical currents at low levels without precip.
Indicate fair weather
105
Cumulonimbus clouds have Violent vertical currents that at times are in excess of __ KT and contain the greatest turbulence.
50 KTS
106
Mammatus clouds are an indication of stable or unstable air?
Unstable
107
A stratus cloud covering half the sky at an altitude of 2 000 feet ASL over an airport with an elevation of 1 000 feet ASL would be forecast in a TAF as
a.SCT010.
b.BKN010.
c.SCT020.
d.BKN020.
A
METAR and TAF cloud heights are given in feet AGL / height above aerodrome elevation.
108
At an airport with an elevation of 500 feet ASL there is two stratus layers overhead. The first layer is between 1 000 to 1 500 feet ASL and the second layer at 2 000 to 2 500 feet ASL. Each layer occupies 3/8 of the sky which would be forecast on a TAF as
a.SCT005 BKN015.
b.SCT010 BKN020.
c.SCT005 SCT015.
d.SCT010 SCT020.
A
Two scattered layers of 3/8 on top of each other cover more than half of the sky. Therefore the upper layer acts as a ceiling, when looking down from above the two layers are 5/8 and greater of the ground would be covered by clouds.
109
No ceiling is said to exist when sky coverage is less than ____
5/8
110
Which cloud may produce light to moderate precipitation?
a.ST
b.NS
c.SC
d.AS
B
111
Which orographic cloud forms as a result of gradient winds shifting from the surface to that at altitude?
Rotor cloud
112
Wind is vertical movement of air caused by pressure differences.
True or false?
False, it is the horizontal movement of air cause by pressure differences
113
What is an isobar?
imaginary lines which join points of equal MSL (mean sea level) pressure.
114
What is a pressure gradient?
This is the rate of change of pressure over a distance.
115
If the isobars are close together then the pressure gradient is shallow producing light winds.
True or false?
False, it would be a steep gradient with strong winds
116
Wind in the northern hemisphere is deflected to the ____ because of the ____ _____
Right, Coriolis force
117
geostrophic wind is the resultant wind at heights approximately ____-____ feet above the ground. It flows ___ to the isobars
2-3,000 ft
Parallel
118
What is buys ballot law?
if you stand with your back to the wind, in the Northern hemisphere, the low pressure is always on the left and the high pressure on the right.
119
What are the names and locations of the three cells in the tricellular model?
Hadley cell, 0-30 degrees (equator)
Ferrel cell, 30-60 degrees
Polar cell, 60-90 degrees (North Pole)
120
• Winds ____ and _____ during a climb out.
• Winds ____ and _____ during an approach.
Veer and increase
Back and decrease
121
A city or extremely rough terrain has a great effect on the wind speed and direction. Terrain like this can change the direction by as much as ___ degrees
40 degrees
122
Define gust
A brief rapid change of wind direction and/or speed.
123
Define squall
A prolonged change of wind direction and/or speed. By definition, this would last for a minute or more.
124
• During the day the winds tend to ____ and _____.
•during the night the winds tend to ____ and _____
Veer and increase
Back and decrease
125
What is a sea breeze?
On onshore breeze from the sea
126
What is a land breeze?
Wind flowing out to sea from the land, usually occurs at night
127
What is anabatic wind?
What is katabatic wind?
Anabatic wind is heated by the sun and flows upslope in valleys and mountains
Katabatic wind is formed by radiation cooling flowing back downslope at night, and snow covered slopes will cause this during the day as well
128
What is wind shear?
Wind shear is defined as a change in wind speed and/or direction.
129
What are the three main jet streams?
Where can they be found?
• Polar Front Jet Stream (PFJS)
• Subtropical Jet Stream (STJS)
• Easterly Equatorial Jet Stream (EEJS)
They are found in the upper boundaries between each of the tricellular circulations
130
What are the characteristics of a jet stream?
• Very strong high altitude winds of 60 knots or more.
• Thousands of miles long and hundreds of miles wide.
131
The ____ Jet Stream is the most important jet stream found in the northern Hemisphere.
Polar
132
Jet streams tend to move ____ (north/south) in terms of latitude in the winter and they will do this along with their associated fronts.
Jet core speeds tend to be ____ (lower/higher) in the winter than in summer.
Jet stream vertical shear varies from __ to __ knots per 1 000 feet
South
Higher
5-20 knots
133
• Turbulence is frequent on the ____ (warm/cold) air side, due to the sudden drop in wind speed.
• Turbulence also is more common ____ (above/below) the core, between the core and the tropopause.
Cold air side
Above the core
134
When jet stream turbulence is encountered while flying with a crosswind, typically from north to south or south to north, observe the OAT gauge for a minute or two and
• if the temperature rises, ____ to get out of turbulence;
• if the temperature falls, ____ to get out of turbulence;
• if the temperature remains constant, ____ as convenient to get out of turbulence.
Climb
Descend
Climb or descend
135
What is a low level jet stream?
The low level jet stream is a sheet of strong winds thousands of miles long and hundreds of feet thick that forms over flat terrain in the prairies.
136
It is true regarding jet streams that
a.jet streams tend to move north in the winter along with the associated fronts.
b.jet core speeds tend to be lower in the winter than in summer.
c.the most severe clear air turbulence are usually found on the low pressure side of the jet stream axis.
d.the altitude of the jet cores is higher in the winter.
C
137
Which jet stream is not associated with a frontal system?
a.Subtropical jet stream
b.Polar jet stream
c.Arctic jet stream
d.Sub Arctic jet stream
A
138
Clear air turbulence associated with a jet stream can be anticipated when
a.the 30 KT isotachs are spaced closer than 90 NM on the 250 MB chart.
b.the horizontal temperature lapse rate is steep.
c.traveling on the poleward side of the jet stream axis.
d.all of the above happen.
D
139
Which conditions would give the highest density altitude?
a.Altimeter setting 30.00 inch Hg
Elevation 1 000 feet
Temperature 15°C
b.Altimeter setting 28.50 inch Hg
Elevation 1 000 feet
Temperature -20°C
c.Altimeter setting 29.50 inch Hg
Elevation 1 000 feet
Temperature -15°C
d.Altimeter setting 28.00 inch Hg
Elevation 1 000 feet
Temperature 20°C
D
Find PA 29.92 - 28.00 = 1.92 x 1 000 = 1 920 + 1 000 = 2 920 feet
Density altitude approx 4 000 feet
140
Given: Elevation 780 feet
Surface temperature 22°C
Dew point 3°C
What is the height of the freezing level?
a.9 113 feet AGL
b.8 333 feet AGL
c.6 333 feet AGL
d.2 000 feet AGL
B
CLOUD BASE
(22 - 3) / 3 x 1 000 = 6 333 feet AGL
FREEZING LEVEL
3 / 1.5 x 1 000 = 2 000 feet above cloud base + 6 333 feet = 8 333 feet AGL
The correct answer is: 8 333 feet AGL
141
Given: Elevation 640 feet
Surface temperature 18°C
Dew point 12°C
What is the height of the freezing level?
a.8 000 feet ASL
b.2 000 feet ASL
c.10 000 feet ASL
d.10 640 feet ASL
D
CLOUD BASE
(18 - 12) / 3 x 1 000 = 2 000 feet AGL
FREEZING LEVEL
12 / 1.5 x 1 000 = 8 000 feet above cloud base + 2 000 cloud base = 10 000 feet AGL + 640 feet elevation = 10 640 feet ASL
142
Given: Temperature 20°C
Dew point 14°C
Elevation 1 200 feet
The base of the cloud would be
a.3 200 feet AGL
b.2 000 feet AGL
c.4 000 feet AGL
d.5 200 feet AGL
B
(20 - 14) / 3 x 1 000 = 2 000 feet AGL
The correct answer is: 2 000 feet AGL
143
Given: Altimeter setting 29.52
OAT 25°C
Indicated altitude 13 500 feet
Elevation 3 000 feet
The true altitude would be
a.12 000 feet ASL.
b.13 900 feet ASL.
c.10 500 feet ASL.
d.15 000 feet ASL.
D
144
Aerodrome details: Elevation 980 feet
Temperature 20°C
Altimeter setting 28.28 inch Hg
Circuit height 1 700 feet ASL (700 feet AGL) Joining the circuit at an aerodrome with the altimeter set to 28.92 inch Hg, which is correct?
a.Flying at 80 feet AGL.
b.Flying at 60 feet AGL.
c.Flying at 300 feet AGL.
d.Flying at 720 feet AGL.
A
Altimeter setting difference 28.92 - 28.28 = 0.64 x 1 000 = 640 feet difference
1 700 indicated altitude - 640 too high setting = 1 060 feet ASL height of the aircraft - 980 elevation = 80 feet AGL (above the aerodrome)
Notice the circuit height has rounded up by 20 feet so do not forget to include it.
The correct answer is: Flying at 80 feet AGL.
145
Given: Elevation 2 200 feet
Temperature -20°C
Altimeter setting 30.32
The aircraft can climb to an indicated altitude of 7 000 feet by the time it is near the higher terrain that is at 7 000 feet. What height is the aircraft in relation to the higher terrain?
a.4 425 feet
b.375 feet below the higher terrain
c.2 575 feet below the higher terrain
d.6 600 feet
B
Find PA 29.92 - 30.32 = -0.4 x 1 000 = -400 + 7 000 = 6 600 feet
Calibrated altitude 7 000 - 2 200 = 4 800 feet
The true altitude 2 200 elev + 4 425 absolute alt = 6 625 feet
146
During a flight towards an 8 900 foot mountain range with the altimeter set to 29.98 inch Hg and the OAT of 10°C. The altimeter is indicating 9 500 feet, how much will the flight clear the mountain by?
a.9 530 feet
b.580 feet
c.540 feet
d.630 feet
D
Finding PA 29.92 - 29.98 = -0.06 x 1 000 = -60 + 9 500 = 9 440 feet
indicated altitude less the mountain range to correct the air above the surface
9 500 - 8 900 = 600 feet calibrated altitude
147
Departing with the altimeter set to 28.89 inch Hg and flying at 5 000 feet to an aerodrome with an elevation of 580 feet that has an altimeter setting of 28.98 inch Hg. Without the altimeter being reset, upon landing the pilot will notice the altimeter indicating
a.580 feet.
b.670 feet.
c.490 feet.
d.571 feet.
C
Difference in altimeter settings 28.98 - 28.89 = 0.09
Convert to feet .09 x 1000 = 90 feet
The altimeter is set too low, so it will be reading low. Which means upon landing the altimeter will be reading too low by 90 feet.
The correct answer is: 490 feet.
148
Given: Surface temperature 15°C
Dew point 8°C
Elevation 1 200 feet
The freezing level is at
a.3 533 feet AGL.
b.7 666 feet AGL.
c.5 333 feet AGL.
d.8 533 feet AGL.
B
Calculate cloud base:
15 - 8 = 7 / 3 = 2.333 x 1 000 = 2 333 feet AGL
Calculate freezing level:
8 / 1.5 = 5.333 x 1 000 = 5 333 feet above cloud
Freezing level is 2 333 + 5 333 = 7 666 feet AGL
The correct answer is: 7 666 feet AGL.
149
Given: Surface temperature 12°C
Dew point 0°C
Elevation 850 feet
The base of cloud height is
a.4 850 feet ASL.
b.4 000 feet ASL.
c.8 000 feet ASL.
d.8 850 feet ASL.
A
Calculate cloud base:
12°C - 0°C = 12°C / 3°C = 4 x 1 000 = 4 000 feet AGL + 850 = 4 850 feet ASL
150
If the wind is from the north the area of low pressure is to the
a.north.
b.east.
c.west.
d.south.
B
151
Define an air mass
An air mass is a large body of air, usually 1 000 miles or more across, that has similar properties of temperature and moisture in the horizontal.
152
An air mass will take on the properties of the area in which it formed from stagnation of the air for a long period of time.
True or false?
True
153
• The Source Region of an air mass will always occur in an area of ____ (high/low) pressure.
>____ (fast/Slow) moving highs are the best at forming air masses.
High
Slow
154
The weather in an air mass will be determined by what three things?
Moisture content
Stability of mass
Cooling or heating processes present
155
What are the 6 types of air masses?
• Continental Arctic (cA)
• Maritime Arctic (mA)
• Continental Polar (cP)
> Maritime Polar (mP)
• Continental Tropical (cT)
> Maritime Tropical (mT)
156
What are the 4 common air masses found in Canada?
• Continental Arctic (cA) - (winter)
> Maritime Arctic (mA) - (summer and winter)
• Maritime Polar (mP) - (summer and winter)
• Maritime Tropical (mT) - (summer)
157
Why can we get maritime arctic masses in the summer in Canada?
Abundance of lakes in northern Canada thaw filling air mass full of moisture and warmth making it less stable, forming convection and showers
158
An airmass depicting cooling from below will indicate as ___ on a weather chart
Stable or unstable?
W (cPw) to slow it is warmer than the surface below it.
Stable
159
An airmass depicting warming from below will indicate as ___ on a weather chart
Stable or unstable?
K (cAk) to show it is cooler than the surface below it
Unstable
160
When different air masses collide, the boundaries between the masses are known as
Fronts
161
at the tropopause the temperature of the WARMEST air masses will be
COLDER than an air mass that is generally cooler
True or false?
True, because of the higher tropopause levels nearer to the equator
162
Air masses are defined by
a.their source regions.
b.their present region of occupation.
c.their height.
d.answers (b) and (c).
A
163
What is the order of the air masses typical of North America from south to north?
Maritime Tropical, Maritime Polar, Maritime Arctic and then Continental Arctic.
164
The air mass that is responsible for bringing Canada cool, moist and damp weather is the
Maritime polar
165
The air mass that is responsible for bringing hot and humid weather to Canada is the
Maritime tropical
166
The air mass that brings clear and pleasant weather to the prairies is the
Maritime Arctic
167
An air mass acquires its properties
a.though vertical mixing.
b.from the stagnation of air for a long time period over large areas of the earth.
c.from a series of low pressure systems.
d.mixing of cold and warm fronts.
B
168
the movement of a front is always dependant on what?
The motion of the cold air perpendicular to it
169
What are the different types of fronts?
• Cold Front
• Warm Front
• Occluded Front
• Trowal
• Stationary Front
• Upper front
170
What is a cold front?
What happens at the front?
Do they move fast or slow?
Cold air replacing warm air, wedges under creating frontal lift, steeper slope
Generally fast moving
171
What happens to clouds and precipitation as a cold front passes?
As a cold front moves forward, the clouds get higher and the rain ceases
172
What happens to the weather before, during and after a cold front?
Before:
Winds Beginning in the south to southwest
Temperature - Warm
Pressure - Falling steadily
Clouds - Increasing cumulus, towering cumulus, and cumulonimbus (CU, TCU, and CB) Formed by warm air expanding as it is lifted by the advancing cold air.
Precipitation - Short period of showers
Visibility - Fair to poor in haze
Dew Point - High-remains steady
During:
Winds - Gusting and VEER and increase
Temperature - Sudden drop
Pressure - Sharp rise
Clouds - CB
Precipitation - Formed by warm air expanding as it is lifted by the advancing cold air. Heavy rain, thunder and lightning, and maybe hail
Visibility - Poor but improving
Dew Point - Sharp drop
After passing:
Winds - Becoming a west to northwest
Temperature - Steadily dropping
Pressure - Rising steadily
Clouds - (slow moving, warm air stable) NS, AS, CI (fast moving, warm air unstable) CU
Precipitation - Showers then clearing
Visibility - Good except for in the showers
Dew Point - Lowering
173
How does a warm front work?
Fast or slow moving?
Warm air overrides the cold air and frontal lift causes it to rise, shallow slope
Generally slower
174
What happens with the weather before, during, and after a warm front passes?
Before:
Winds - Beginning in the south to southeast
Temperature - Cool to cold with slow warming
Pressure - Falling gradually
Clouds - Approaching in order: cirrus, cirrostratus, altostratus, nimbostratus, stratus (CI, CS, AS, NS, St), and sometimes fog (FG).
CB in summer when fast moving and warm air is unstable (TCU also likely when air is unstable)
Formed by warm air expanding as it is lifted by the retreating cold air.
Precipitation - Light to moderate: rain, snow, sleet, or drizzle
Visibility - Poor
Dew Point - Steady rise
As it passes:
Winds - Variable and veers
Temperature - Steady rise
Pressure - Leveling off
Clouds - Stratus type, NS when there is precipitation
Precipitation - Drizzle or none
Visibility - Poor but improving
Dew Point - Steady
After passing:
Winds - Becoming a south to southwest
Temperature - Warmer then steady
Pressure - Slight rise followed by fall
Clouds - Clearing with scattered statocumulus (SC), occasionally CB in summer
Precipitation - Commonly none, sometimes light rain or showers
Visibility - Fair in haze
Dew Point - Rise then steady
175
What is an occluded front?
Why does it happen?
Cold front associated with a low catches up to the warm front overtaking it and undercutting it.
It happens because of the greater density of the colder air moves faster
176
What does trowal stand for?
Trough of warm air aloft
177
the weather at an occlusion or trowal can resemble both a warm front and cold front conditions.
True or false?
True
178
What is a stationary front?
What way will the winds blow?
What weather can be expected at the front?
a front that is not moving - neither air mass is replacing the other.
• Winds will be blowing parallel to the front.
• clouds and prolonged precipitation
179
The initial formation of a front is sometimes referred to as _____.
Frontogenesis
180
The dissipation of a front is referred to as _____.
Frontolysis
181
What is an upper front?
What will the surface weather be like?
air is trapped on the surface and the frontal weather is pushed aloft.
There will be fewer indications of the frontal passage for an observer on the surface.
• Winds will not shift, veer.
• Temperature will not change.
• Precipitation is quite likely to fall and appropriate cloud types seen.
• However at a higher altitude the frontal passage weather is similar to normal frontal weather.
182
Why is a fast moving cold front hazardous to pilots?
A very steep cold front forms in the summer • If the warm air is moist and unstable, a line of thunderstorms known as a squall line may develop along this front.
• This is a very narrow band of violent weather.
• The wind veers with frontal passage and is strong, gusty, and turbulent for a considerable period of time after
183
What are some likely weather hazards associated with winter trowals?
Freezing rain, severe icing
184
What elevation is the front drawn on a gfa and sigwx chart?
At the surface
185
How does a mountain wave form?
occurs as winds are forced upward by an impeding mountain range and then descends downward on the lee side.
• Under the right conditions this airflow essentially bounces up and down for some distance downstream of the mountain range.
186
Where are downdrafts most severe in a mountain wave?
Downdrafts can reach as high as ___ fpm
At the ridge or same height as top of summit
5,000
187
Conditions required for mountain wave formation?
- wind direction must be within 30 degrees perpendicular to the mountains
- windward side speed must be 25kt or more
- winds aloft increase with height
- stable air mass, isothermal or inversion near mountain top
188
Average mountain wave wavelength is __ NM.
Average total wave distance, from mountaintop to final dissipation, is ___ NM.
8
100
189
• Larger mountain wave amplitudes occur between ____ to ____ feet above the ridge.
• Generally, the greater the amplitude the ____ (shorter/longer) the wavelength
3,000-6,000 feet
Shorter
190
What 4 clouds can be an indication of a mountain wave/turbulence?
Lenticular
Rotor
Cap
Banner
191
____ clouds usually appear at the crest of a wave
Lenticular
192
Why does a stationary lenticular appear not to move?
• As the air in a mountain wave rises it cools by expansion and condenses out moisture to form the leading edge of the lenticular cloud.
• After the air flows over the crest it continues downward and due to the heat of compression it evaporates and absorbs the moisture.
193
Clouds that possess the greatest amount of turbulence in a mountain wave is the
Rotor clouds
194
Rotor/roll cloud specs?
Should you fly over/under or around them?
• Diameter varies between 600 feet and two miles.
• Center of rotation typically is near the ridgeline.
> 2 000 to 5 000 FPM vertical velocity.
These will produce SEVERE turbulence.
First rotor is typically the most intense although all of them will spell trouble.
You can fly over but expect mountain wave turbulence, second choice is to fly around them. NEVER fly under, they will be too turbulent
195
Cap clouds produce strong updrafts.
True or false?
False, strong downdrafts
196
The absence of clouds in a mountain wave does not mean there is no turbulence. True or false?
True
197
On a GFA mountain wave activity will be depicted if the turbulence is forecast to be _____
Moderate or greater
198
Combining mountain waves and non-standard temperature may result in an altimeter overreading by as much as _____ feet
3,000 ft
199
What happens when two wind streams converge in the mountain valleys?
What happens when they diverge?
They increase to the combined speeds of each wind added together upon convergence.
Opposite is true upon divergence
200
• The best advice is that all light aircraft pilots should stay out of the mountains when the wind speed at the mountain peak level is ___ KT or greater.
• Fly at least ___ %higher than the mountain range.
• ____ the rotor clouds in the low-level turbulence area.
• ____ (do/do not) rely on altimeter indications.
20kt
50%
Avoid
Do not
201
When crossing ridges from the downwind side, do so at a ___° angle and by at least ____ feet above when strong winds are present -this gives the option to turn back if needed.
45 degree
3,000 feet above
202
The most severe mountain wave conditions are created in strong airflows blowing at ____ angles to the range and in ____ (stable/unstable) air.
Right angles
Stable air
203
A greater intensity of turbulence is found while flying
a.at slower airspeed.
b.downwind into a mountain wave.
c.upwind into a mountain wave.
d.towards the mountain from the windward side.
B
204
Lenticular clouds often form
a.at the ridge height of the mountain.
b.between the ridge height and a layer of very dry air.
c.near the surface.
d.from 20 000 to 40 000 feet.
D
205
What is convective turbulence?
What clouds are associated with this?
On A gfa what do these clouds imply?
- Caused by the unequal heating of the earth's surface. Rocks, roads, soils heat up faster than grass or water and cause rising pockets of heat that can rise a few thousand feet per minute.
- TCU, CB, ACC, CU are associated with convective turbulence.
- on a gfa they imply significant turbulence/icing
206
What is mechanical turbulence?
The gfa will only show mechanical turbulence if it is expected to be ____ or ____.
Caused by friction between the air and the ground.
• It is also created when wind encounters trees or man made objects like buildings.
Moderate or severe
207
What is frontal turbulence?
Commonly occurs with warm or cold fronts?
• Frontal wind shear tends to happen with fronts that have ___ (shallow/steep) wind gradients.
• Fronts with temperature changes of __ degrees or more may cause this to happen.
• Another mechanism is a front that
is moving at high speed, Typically ___ knots or more.
• Caused by the friction that occurs between two opposing air masses
• More commonly associated with cold fronts, but it can occur at warm fronts as well.
• 5 degrees
• 30 knots or more.
208
What is Orographic turbulence?
This is caused by friction in air currents through a mountainous regions as the air moves up mountains or hills.
209
What are some causes of wind shear?
• Micro-bursts (Virga-possible indication)
• Jet-streams
• Topography
• Fast moving fronts
210
What is the difference between speed shear and directional shear?
Speed shear is wind of different speeds at different altitudes
Directional shear is wind of different directions at different altitudes
211
Low-level wind shear is defined as a significant non-convective wind shear that could adversely affect aircraft operation within ____ feet AGL over the aerodrome.
1500 feet
212
What are some guidelines for reporting wind shear?
• A wind speed change that exceeds 25 KT within 500 feet AGL;
• A wind speed change exceeding 40 KT within 1000 feet AGL;
• Wind changing by 50 KT within 1500 feet AGL;
• A pilot reporting a loss or gain of lAS of 20 KT or more within 1500 feet AGL.
213
What is virga? How does it factor in with low level wind shear?
Virga is rain that evaporates before reaching the ground.
• Similar to a microburst, virga produces strong downdrafts.
• As the rain falls it drags the air downward.
• When the rain falls through a layer of drier air below, the rain evaporates causing cooling of the descending air.
• The cooled air will continue downward, without the rain to indicate the presence of a strong downdraft.
Once the strong downdraft reaches the surface the divergence of the air created by the surface leads to wind shear.
214
What are the examples of turbulence reporting criteria?
• Light: Slight erratic changes in attitude and/or altitude, less than
15 KT airspeed fluctuation.
• Moderate: Greater intensity than light chop, usually causes bumps or jolts but aircraft remains in control at all times.
• Severe: Large abrupt changes, momentarily out of control, airspeed fluctuations in excess of 25 KT.
• Extreme: Airplane is violently
tossed, control impossible and may cause structural damage.
• Light Chop: Slight rapid and
rhythmic bumps without changes in altitude or attitude.
215
Which condition would produce the smoothest flying?
a.Flight above the clouds.
b.Flight below the clouds.
c.Flight just above the surface of Earth.
d.In the middle of the clouds.
A
216
Wind shear is a sudden change in the wind's
a.speed only.
b.speed and/or direction.
c.direction only.
d.vertical speed only.
B
217
Turbulence in the lower levels is to be expected when
a.warm air moves over a warm surface.
b.cold air moves over a warm surface.
c.it's very cold.
d.the pressure of the air is very high.
B
218
What are some hazards associated with thunderstorms?
Tornadoes
Waterspouts
Downbursts
Microbursts
Severe Turbulence
Hail
Heavy Rain
Wind Shear
Lightning
Severe Icing
219
What are the 3 major ingredients required for the formation of a thunderstorm?
High moisture, unstable air (steep lapse rate) and a lifting agent
220
What are the 3 stages of a thunderstorm?
Are they updraft or downdraft?
Cumulus stage - updraft
Mature stage - up and down drafts
Dissipating stage- downdraft
221
How does the mature stage of a thunderstorm work?
Warm air rises until it reaches air that is warmer, then it can no longer rise, which is usually the tropopause where the cap forms. Air is forced to spread outward creating an anvil, and the water coalesces into heavier droplets, freezing into ice pellets. As it falls it melts and becomes rain.
222
In the mature stage, downdrafts tend to be strongest in areas of heavy precipitation. True or false?
The heavy rain cools and drags down the air with it so downdrafts may reach speeds of up to ____ fpm
True
2,000
223
What happens during the dissipating stage of a thunderstorm?
As the heavy precipitation falls through the cloud, the cloud cools, and then downdrafts dominate the base of the cloud.
224
What is an embedded thunderstorm?
Obscured by clouds
225
What are Orographic thunderstorms ?
Created as air is forced upwards over mountainous terrain
226
What is a convective thunderstorm?
Hot air rising creates energy source for development of thunderstorms.
227
What is a frontal thunderstorm?
What is a common hazard with these?
Created by frontal lift.
Formation of squall line storms, can often be embedded creating a greater hazard.
228
Where is a squall line usually found?
The most severe up/downdrafts can be found at the leading or trailing edge of the storms?
Ahead of fast moving cold fronts,
Leading edge
229
The probability of lightning strikes occurring to aircraft is greatest when operating at altitudes where temperatures are between ___ and ___ C.
-5 and +5 C
230
How does hail form?
Strong updrafts push water droplets above the freezing level causing them to freeze. Another updraft can push them up and re-freeze them at a larger size. This process can repeat many times until the weight of the hail is heavier than the updraft force. Frequently happens under the anvil
231
Severe turbulence may extend up to __ NM from severe thunderstorms.
20 nm
232
If avoiding storms visually, stay at least __ miles on the downwind side and __ miles on the upwind side.
• Using radar, increase the avoidance distance up to __ miles due to radar error.
10,3
20
233
____ clouds are telltale signs that funnel clouds maybe forming or may have formed.
Mammatus
234
If flight through a thunderstorm cannot be avoided, minimize critical icing encounters by
a.flying at an altitude that is lower than the freezing level.
b.flying at an altitude that is higher than the freezing level.
c.planning a course that will take the aircraft through the storm in the shortest time.
d.answers (a) and (c).
D
235
In a tornado the path of destruction can reach . . . . . and wind speeds of . . . . . have been recorded.
a.2 to 2.5 miles, 280 MPH
b.2.5 to 10 miles, 400 MPH
c.0.25 to 2.5 miles, 180 MPH
d.1 to 5 miles, 200 MPH
A
236
During what time of the year are tornadoes most likely to occur in North America?
a.Winter and spring
b.Spring and summer
c.Summer and autumn
d.Autumn and winter
B
237
What is fog?
What are the basic ingredients needed for fog to form?
a cloud that is in contact with the ground.
-moisture (high relative humidity)
-small condensation nuclei
-light winds
-cooling process or one that adds moisture for the condensation
238
What are the 7 types of fog?
• Radiation Fog
• Advection Fog
• Upslope Fog
• Frontal Fog
• Steam Fog
• Ice Fog
• Industrial Fog
239
What is radiation fog?
Formed by radiation cooling on clear nights where the relative humidity is high and light winds (1 to 5 KT) are present.
Mostly likely shortly after sunrise
240
What is advection fog?
• Formed by advection cooling as a result of horizontal movement of warm moist air over a land or sea surface colder than itself.
• The thickest advection fog will usually form at night with winds up to about 15kts.
• Very common during winter warming periods and early spring thaws.
241
What is upslope fog?
Upslope Fog is basically a cloud resting on the ground as a result of a light to moderate upslope wind.
242
What is frontal fog?
What is another name for it?
• Continuous precipitation ahead of a warm front falls into colder air below.
• As the rain evaporates saturation occurs causing fog.
•also known as precipitation fog
243
What is steam fog?
What is another name for it?
Ideal conditions are when extremely cold dry air blows over a body of open water, such as a lake, river, or the ocean.
• The cold air mixes with the warm moist air over the water, the moist air cools until the excess water vapour
condenses and a fog or mist will form.
• also known as sea smoke
244
What is ice fog?
This type of fog is often created by the exhaust from engines or by the exhaust from large industrial centres on a cold winter's day.
will sometimes form when the temperatures are significantly below zero, colder than - 30°C or so.
245
What is the reporting visibility standard for it to be called mist or fog?
Mist is 5/8 up to 6 sm
Fog is visibility less than 5/8 sm
246
Haze forms on days with cool temperatures. True or false?
False, forms on days of high temps
247
when a vertical visibility (VV) is reported in a METAR, is it considered to be a VFR ceiling?
Yes
248
What is a whiteout?
The phenomenon occurs when you are in the presence of a large flat area and the overcast sky blends in with the ground. Pilots flying VFR therefore lose all the essential clues for continuing their flight safely, even if visibility remains adequate and the ceiling is high.
249
Why can you have fog near industrial areas? ( industrial fog )
Industrial areas can have high numbers of condensation nuclei, and can create intense localized fog.
• These types of fog will sometimes be a brown or dark color due to carbon and dust particles.
250
Fog can be anticipated when the
a.temperature and dew point spread is small and decreasing.
b.temperature and dew point spread is great and increasing.
c.winds are gusty.
d.air pressure is high.
A
251
What are the differences between radiation fog and advection fog?
a.Radiation fog forms due to surface cooling at night in a light wind and advection fog forms when warm humid air flows over a cold surface.
b.Radiation fog forms only on the ground and advection fog only on the sea.
c.Radiation fog forms due to night cooling and advection fog due to daytime cooling.
d.Radiation fog is formed by surface cooling in a calm wind and advection fog is formed by evaporation over the sea.
A
252
Frontal fog is most likely to occur in
a.winter, in the early morning.
b.summer, in the early morning.
c.advance of a cold front.
d.advance of a warm front.
D
253
Frontal fog occurs when very
a.humid warm air meets with very humid cold air.
b.humid warm air meets with dry cold air.
c.dry cold air meets with very dry warm air.
d.humid cold air meets with dry warm air.
A
254
In what ways do advection fog, radiation fog, and steam fog differ in their formation or location?
a.Advection fog deepens as wind speed increases up to 20 KT, steam fog requires calm or very light wind, and radiation fog forms when the ground or water cools the air by radiation.
b.Radiation fog is restricted to land areas, advection fog is most common along coastal areas, and steam fog forms over a water surface.
c.Steam fog forms from moist air moving over a colder surface, advection fog requires cold air over a warmer surface, and radiation fog is produced by radiational cooling of the ground.
d.None of the above.
B
255
Fog associated with a warm front is a result of saturation due to
a.subsidence.
b.nocturnal cooling.
c.evaporation of surface moisture.
d.evaporation of precipitation.
D
