ITA-Block 3 Flashcards
1
Q
5 elements of the atmosphere
A
Nitrogen Oxygen Carbon dioxide Ozone Water vapour
2
Q
Where does 99% of weather occur?
A
The lowest 35,000 feet of the atmosphere.
3
Q
Which is more dense, cold or warm air?
A
Cold air.
4
Q
True or false:
An aircraft can take off more easily/quickly in warm air.
A
False.
5
Q
The lowest level of the atmosphere
A
Troposphere
6
Q
The boundary between the lower levels of the atmosphere
A
Tropopause
7
Q
The upper level of the atmosphere
A
Stratosphere
8
Q
Where in the atmosphere does most weather occur?
A
In the troposphere
9
Q
How do you know when you exit the troposphere?
A
The temperature stays constant, and sometimes increases due to the chemical activity of the ozone
10
Q
What is the average height of the tropopause?
A
11km
11
Q
Where is the tropopause higher?
A
Over the equator (up to 18km)
12
Q
Where is the tropopause lower?
A
Over the poles
13
Q
What factor affects the height of the tropopause?
A
Temperature
14
Q
What are the four conditions of the ICAO standards?
A
- Air is perfectly dry (0% humidity)
- The mean sea level pressure is 29.92 inches of mercury
- The temperature at sea level is 15 degrees Celsius
- Temperature lapse of 1.98 degrees Celsius for every 1000ft
15
Q
MSL
A
Mean sea level
16
Q
Both radar altimeter and pressure altimeter are the same when…
A
The four conditions of ICAO are met
17
Q
Is there more or less distance between pressure levels in warm weather than the ICAO standard?
A
More; altimeter indicator shows a lower altitude than he ACs actual altitude
18
Q
Is there more or less distance between pressure levels in cold weather than ICAO standard?
A
Less; the altimeter indicator reads a higher altitude than the ACs actual altitude.
19
Q
List the properties of the atmosphere
A
Mobility
Capacity for compression
Capacity for expansion
20
Q
What are the two basic cloud forms?
A
Stratiform and cumuliform
21
Q
Cumuliform are formed as the result of…
A
Rising air currents
22
Q
Four basic types of cumulus clouds
A
- cumulus
- towering cumulus
- cumulonimbus
- altocumulus castellanus
23
Q
Cu
A
Cumulus abbreviation
24
Q
TCU
A
Towering cumulus abbreviation
25
CB
Cumulonimbus abbreviation
26
ACC
Altocumulus castellanus abbreviation
27
What is the maximum height of a cumulonimbus cloud?
60,000 to 70,000 feet in height
28
What is the average height of a cumulonimbus cloud?
35,000 feet
29
Another name for a towering cumulus
Cumulus congestus
30
Cumulus impact on aviation
- Bumpy flight underneath
| - updrafts below and in cloud
31
Towering cumulus impact on aviation
- Turbulence
- icing
- strong updrafts
32
Cumulonimbus impact on aviation
- thunderstorm
- precipitation
- winds
- violent vertical currents
- hail
- extreme turbulence
- extreme icing
- lightning
33
Altocumulus castellanus impact on aviation
- turbulence
- precipitation
- icing
- updrafts below and in cloud
34
What is sky coverage expressed in?
Oktas
35
METAR
Meteorological aerodrome report
36
Sky coverage clear
No clouds are present
37
SKC
Clear sky coverage abbreviation
38
Few sky coverage
1/8 or 2/8 covered by cloud
39
Scattered sky coverage
3/8 or 4/8 of sky covered
40
SCT
Scattered coverage abbreviation
41
Broken Sky coverage
5/8, 6/8 or 7/8 of sky covered
42
BKN
Broken coverage abbreviation
43
Overcast sky coverage
8/8 sky covered
44
OVC
Overcast coverage abbreviation
45
Stratiform
Horizontal cloud formation
46
Cumuliform
Vertical cloud formation
47
Atmospheric pressure
Pressure due to the weight of overlying air
48
How can atmospheric pressure be measured?
- inches of mercury
- hectopascals
- millibars
49
With height, does atmospheric pressure increase or decrease
It decreases with height
50
Isobars
Curved lines that join locations of equal MSL
| There are 4 hectopascals of pressure differences between each isobar
51
The difference between two isobars
4 hectopascals
52
Another term for a LOW
Cyclone or depression
53
Another term for a HIGH
Anticyclone
54
A bulge in a low pressure area
Trough
55
A bulge in an area of high pressure
Ridge
56
Buy's ballot law
In the northern hemisphere, if you stand with your back to the wind, the area of LOW pressure is always to your left.
57
In which direction does air flow around a LOW?
Counter-clockwise
58
In which direction does air flow around a HIGH?
Clockwise
59
Does air around a LOW tend to be cloudy or clear?
Cloudy because air rises, cools and condenses forming cloud
60
Does air around a HIGH tend to be cloudy or clear?
Clear because the air flows out towards a low and sinks, heating and evaporating
61
Characteristics of a low pressure system
- cloudy
| - covers from 10km to hundreds of km
62
Characteristics of high pressure systems
Clear, good weather
| Can cover hundreds to thousands of km
63
Pressure gradient
The rate of change of pressure horizontally measured in km.
64
How does the pressure gradient relate to the speed of winds?
The greater the pressure gradient (faster the change in pressure), the stronger the winds.
65
Wind
Air moving from an area of high pressure to an area of low pressure
66
VRB
Abbreviation for variable
67
Under which circumstances is variation in wind expressed in a report?
If the wind direction has varied 60 degrees or more in the last ten minutes
(140V230)
68
Coriolis force
The deflection of air to the right (in the northern hemisphere) because of the rotation of the earth
69
Veering
When the wind makes a clockwise change in direction
| This usually occurs when climbing
70
Backing
When the wind makes a counter-clockwise change in direction
| This usually occurs when descending
71
What do the hooks on an arrow depicting wind represent?
Each hook represents a speed of 10 knots
72
How does height affect wind speed?
Wind speed increases with height due to loss of friction
73
Directional shear
Wind shear caused by the meeting of two winds in opposite directions
74
Speed shear
Wind shear caused by the meeting of wind at different speeds
75
Jet stream characteristics
- found from 20,000 to 40,000 feet
- higher in the summer
- higher in the tropics than over the poles
- minimum speed of 60KTS
- thousands of miles long
- few hundred miles wide
- few thousand feet thick
76
True or false: wind flows perpendicular to the isobars?
False
77
If the earth were not rotating, how would the wind flow in relation to the isobars.
If the earth did not rotate, the wind would flow perpendicular to the isobars.
78
Water vapour
Water in its gaseous form
79
Condensation
The process by which water vapour turns to water
80
Sublimation
When a gas turns to a solid
81
Evaporation
When a liquid changes to a gas
82
Water vapour content
The quantity of water vapour present in the air
83
Absolute humidity
The actual amount of water vapour in a unit of air
84
Relative humidity
The ratio of the amount of water vapour in a unit of air compared to the amount the air at that temperature can hold.
85
Saturation
When the amount of water vapour is at the maximum possible for the unit of air at a given temperature
86
How does temperature affect how much water vapour a unit or air can hold?
The warmer the air, the more water vapour it can hold.
87
Dew point
The temperature to which air has to cool to achieve saturation.
88
What does it mean if the relative humidity is 100%?
The air is saturated
89
What does it mean if the relative humidity is 0%?
There is no moisture content in the air.
90
Stable air
Air that will resist upward or downward displacement, and returns to its original place
91
Unstable air
Air which tends to move further away without additional lift
92
What kind of cloud will appear in stable air?
Stratus
93
What kind of cloud will appear in unstable air?
Cumulus
94
What are the five lifting agents?
- convection
- orographic lift
- frontal lift
- mechanical turbulence
- convergence
95
Convection
When air is heated from below by contact with the earth's surface
96
Orographic lift
Air is forced to rise up sloping terrain
97
Frontal lift
Air is forced to rise by a wedge of colder and denser air
98
Cold front
When an advance of cold air undercuts warmer air, causing frontal lift
99
Warm front
When cold air is retreating and warm air overruns the dense air causing frontal lift
100
Mechanical turbulence
A type of lift caused by friction between the air and the ground
101
Convergence
Occurs at the centre of LOW pressure areas. Air converges and is forced to rise.
102
Three requirements for condensation to occur
- saturation
- cooling process
- condensation nuclei
103
Air mass
A large section of the troposphere with relatively uniform properties of temperature and moisture in the horizontal
104
Maritime air mass
Formed over large body of water
| Humid
105
Continental air mass
Formed over a large land area
| Air mass is dry
106
cA
Continental arctic abbreviation
107
mA
Maritime arctic abbreviation
108
mP
Maritime polar abbreviation
109
mT
Maritime tropical abbreviation
110
cP
Continental polar abbreviation
| Not usually found in North America
111
cT
Continental tropical abbreviation
| Not usually found in North America
112
Arctic air mass
Cold air mass
113
Polar air mass
Temperate air mass
114
Tropical air mass
Warm air mass
115
Three main factors that determine weather
- moisture content
- the cooling process
- the stability of the air
116
Cooling processes that contribute to cloud formation
- cooling by radiation (by being in contact with cold ground)
- advection of warm air over a colder surface
- expansion brought about by a lifting process
117
How many air masses can there be over North America?
Four in winter (three frontal systems)
| Three in summer (two frontal systems)
118
Front
The transition zone between two air masses
119
Stationary front
When neither air mass is advancing or retreating
120
Fronts during summer
Maritime (M): over southern Canada
| Polar (P): over the U.S.
121
Fronts during winter
Arctic (A)
Maritime (M)
Polar (P)
Found in this order on a map
122
Polar front theory
States that there are only two air masses (polar and tropical) and one front:
123
Symbol used to identify a cold front
Arrow end
124
Symbol used to identify a warm front
Half circle
125
Symbol used to identify a stationary front
Alternating between arrow ends and half circles
126
Factors that affect the severity of front weather
- slope of frontal surface
- speed of frontal movement
- temperature of lifted air mass
- moisture content of lifted air mass
- stability of the lifted air mass
127
In the case of a cold front, when does the temperature change usually occur?
When the front reaches the station
128
In the case of a warm front, when does the change in temperature usually occur?
The change may begin before the front reaches the station
129
How does a warm front affect the dew point temperature?
The dew point temperature will increase
130
How does a cold front affect the dew point temperature?
The dew point temperature will decrease
131
What type of slope does a cold front usually have?
A steep slope
132
What kind of slope does a warm front usually have?
A shallow slope (because of the frictional drag of the retreating cold air mass)
133
Average slope of a cold front
1:50
134
Average slope of a warm front
1:200
135
Average slope of a stationary front
1:100
136
How does the slope of a front affect cloud formation?
On a shallow slope, the cloud will cover a wide area, where a steep slope will produce a narrow band of cloud
137
How does the slope of a front affect its speed?
The steeper the slope, the faster the front moves
