9 Aviation Weather Flashcards
(323 cards)
1
Q
What are the 4 main layers of the atmosphere (increasing altitude)?
A
Troposphere > Stratosphere > Mesosphere > Thermosphere
2
Q
Describe the Troposhere
A
Region between surface and Tropopause at approx 36,000ft
Temp reduces with Altitude (-1.98C/1000ft)
Approx. +15C at surface to -56C at Tropopause
3
Q
Describe the Stratosphere
A
Region between Tropopause and Stratopause (36,000 - 160,000 ft)
Temperature inversion occurs due to presence of Ozone (O3)
Approx. -56C at Tropopause to 0C at Stratopause
4
Q
Describe the Mesosphere
A
Region between Stratopause and Mesopause (160,000 - 280,000 ft)
Temperature reduces with height due to CO2 radiative cooling
Approx 0C at Stratopause to -90C at Mesopause
5
Q
Describe the Thermosphere
A
The region above 280,000 ft and extends to ‘space’
Temperature increases with altitude
6
Q
Does the height of the Tropopause vary between the equator and the poles?
A
Yes.
Poles approx. 25,000 ft
Equator approx. 55,000 ft
7
Q
Describe the 5 points of significance of the Tropopause
A
- Lid of the weather (rarely get clouds above this point)
- Jetsream and high winds (max wind speed around here)
- Clear Air Turbulence (CAT)
- Condensation trails (con-trails) most common around here
- Jet engines are most efficient
8
Q
Name the 4 different pressure settings
A
QFE - Field Elevation (Airfield)
QNH - At airfield corrected for mean sea level
RPS - Regional pressure setting
SPS(SAS) - Standard Pressure Setting
9
Q
Describe QFE pressure setting
A
Pressure setting that would read 0 ft at runway height
10
Q
Describe QNH pressure setting
A
Pressure setting that would read airfield elevation AMSL at runway
11
Q
Describe RPS pressure setting
A
Pressure setting provided per hour for different regions
12
Q
Describe SPS pressure setting
A
When flying at higher altitudes this is 1013.2 hPa so all aircraft are flying off the same datum pressure
13
Q
What are the 4 properties we are concerned with in the Air?
A
Pressure
Temperature
Humidity
Density
14
Q
How much does pressure vary with altitude (high + low level)?
A
Near surface 1hPa per 30 ft
> 20,000 ft. 1 hPa per 50 ft
15
Q
Name the 7 Int’l Std Atm (ISA) properties (titles only)
A
Pressure at surface Temp at surface Temp lapse rate Pressure lapse rate Height of Tropopause Temp at Tropopause Air Density
16
Q
What are the 7 Int’l Std Atm (ISA) properties (titles + values)
A
Pressure at surface = 1013.2 hPa Temp at surface = 15C Temp lapse rate = -1.98C/1000 ft Pressure lapse rate = 1 hPa/30 ft Height of Tropopause = 36,090 ft Temp at Tropopause = -56.5C Air Density = 1.225 kg/m^3
17
Q
1 hPa is equivalent to what older unit?
A
1 mbar
18
Q
What is the Earth’s main source of heating?
A
The Sun
19
Q
What is the heat coming from the Sun known as?
A
INcoming SOlar radiaTION
INSOLATION
20
Q
When the Sun’s energy reaches the Earth what happens to it? (percentages and where/what)
A
50% - absorbed by the Earth’s surface
20% - absorbed by the atmosphere
30% - reflected/lost back to space
21
Q
Name the 3 methods of heat transfer
A
Convection, Conduction, Radiation
22
Q
Warm air …. , cold air …. (think direction)
A
rises
sinks
23
Q
What 5 factors will impact how much energy gets to the Earth’s surface?
A
Atmospheric Conditions Time of Day Season/Tilt of the Earth Latitude Distance to the Sun
24
Q
The largest variation between day/night temperatures is seen over LAND or SEA?
A
LAND
25
The sea is warmest when?
Autumn/Early Winter
26
The sea is coolest when?
Spring/Early Summer
27
Going from Solid > Liquid is known as...
Melting
28
Going from Liquid > Gas is known as...
Evaporating
29
Going from Gas > Liquid is known as...
Condensing
30
Going from Liquid > Solid is known as...
Freezing (Solidifying)
31
Going from Solid > Gas is known as...
Sublimation
32
Going from Gas > Solid is known as...
Deposition
33
What is ABSOLUTE humidity?
The measure how actually how much water vapour is present in the air
34
What is RELATIVE humidity?
The ratio between how much water vapour is actually in the air over the capacity of the water vapour that can be in the air at that temperature. Expressed as a %
35
Relative humidity is expressed as a what?
%
36
Absolute humidity is expressed as what?
kg/m^3
37
When the air cannot hold anymore water vapour, it is said to be?
SATURATED
38
Dry air has a relative humidity (RH) of ???
<100%
39
What is the Dew Point?
The temperature when air is saturated at that given absolute humidity when cooled at constant pressure.
40
What does 05/05 mean in a METAR?
Temp 5C, Dew Point 5C, Humidity 100%
41
Name the 6 types of precipitation
```
Rain
Hail
Freezing Rain
Snow
Sleet
Drizzle
```
42
What is the minimum diameter for hail to be defined as such?
5mm
43
What are the designations for the 6 precipitation types?
```
Rain - RN
Hail - GR/GS
Freezing Rain - FZRA
Snow - SN
Sleet - RASN
Drizzle - DZ
```
44
Water existing below 0C is known as ....
supercooled water
45
Supercooled water can exist down to what temperature?
-40C
46
What terms are used in the water cycle?
```
Evaporation
Condensation
Precipitation
Accumulation
Surface Run-off
Infiltration
```
47
What device is used to collect met data in the atmosphere?
Radiosonde
48
What does a radiosonde measure in the atmosphere?
```
Temperature
Pressure
Humidity
GPS (Lat/Lon) -> Wind Dir/Speed
Altitude
```
49
What does ELR stand for?
Environmental Lapse Rate
50
What is the ELR?
Environmental Lapse Rate. The actual lapse rate in the atmosphere
51
A region in the atmosphere where the temp remains constant with height is called an ....
Isothermal layer
52
A region where temperature increases with height is called an .....
Inversion
53
Another line of interest rising through the atmosphere is the .....
Dew Point Line
54
When the TEMPERATURE and DEW POINT are at or close to the same temperature, what might we expect to see?
Cloud formation
55
What is an adiabatic process?
No energy transferred in or out of a system
56
Describe the DRY ADIABATIC lapse rate (acronym + rate)
DALR
| -3C/1000ft
57
Describe the SATURATED ADIABATIC lapse rate (acronym + rate)
SALR
| -1.5C/1000ft
58
ELR <1.5C/1000ft. The system is therefore ......
STABLE
59
ELR >1.5C/1000ft and <3C/1000ft. The system is therefore ......
CONDITIONALLY UNSTABLE
60
ELR >3C/1000ft. The system is therefore ......
UNSTABLE
61
What are the 3 kinds of stability
Absolute Stability
Absolute Instability
Conditional Instability
62
Describe Absolute Stability
ELR < SALR and DALR
63
Describe Absolute Instability
ELR > SALR and DALR
64
Describe Conditional Instability
ELR between SALR and DALR
65
Stable atmospheric conditions occur when an air packet _____ to its original level.
RETURNS
66
Unstable atmospheric conditions occur when an air packet ________________ its original level.
CONTINUES TO MOVE AWAY FROM
67
What is the average SALR?
1.5C/1000ft
68
What is the average DALR?
3C/1000ft
69
T or F? Temp inversions usually make the atmosphere more unstable.
FALSE
70
Warming the air from BELOW would make the air UNSTABLE or STABLE?
UNSTABLE
71
What is an isothermal layer?
A layer where the temperature remains constant with height.
72
If the ELR is 3.5C/1000ft what would the stability be?
UNSTABLE
73
TRUE or FALSE? The temperature at the tropopause is colder in a warm airmass compared to a cold air mass
TRUE
Warm air masses reach higher altitudes and therefore are cooler at the tropopause.
74
In descending order, list the layers of the atmosphere.
Thermosphere
Mesosphere
Stratosphere
Troposphere
75
Around the UK, at what time of year are sea temperatures likely to be lowest?
SPRING
76
TRUE or FALSE? When water droplets evaporate, latent heat is released?
FALSE
Heat is absorbed
77
If cool air is heated from below, what happens to it's stability?
It becomes more unstable
78
What is an isothermal layer?
A layer where temperature is constant with height
79
What is the lowest temperature that water can exist as a liquid in the Earth's atmoshere?
-40C
Supercooled water
80
What are the two main things we want to known about the wind?
Speed (Mean and Gusts)
Direction
81
Ground windspeed can be measured up to __ meter(s) off the ground
10 meters
82
What piece of equipment is used to measure Wind Speed?
Anemometer
83
Wind speed is measured in what unit?
Knots
84
If the gust speed is >__ kts more than the MEAN wind speed. Then the Met should inform you.
>10 kts
85
The MET office typically provide wind direction in DEGREES ____
TRUE
86
ATC typically provide wind direction in DEGREES ____
MAGNETIC
87
You name the wind direction after where the wind IS GOING/COMING FROM? (Choose one)
COMING FROM
88
What does 28015KT tell us?
Wind from 280
| Mean speed 15 kts
89
What does 16005KT tell us?
Wind from 160
| Mean speed 05 kts
90
What does 08020G30KT tell us?
Wind from 080
Mean speed 20 kts
Gusts 30 kts
91
What does 18010KT tell us?
Wind from 180
| Mean speed 10 kts
92
If the wind is changing in an anti-clockwise direction, it is said to be _____
"BACKING"
93
If the wind is changing in an clockwise direction, it is said to be _____
"VEERING"
94
The drive of air from High to Low Pressure is known as the ______ _____ _____(___)
PRESSURE GRADIENT FORCE (PGF)
95
The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the N. Hemisphere
90 deg to the RIGHT of direction of travel
96
______ Wind moves parallel to isobars
GEOSTRAPHIC
97
Describe the "Buys Ballot" Law
N. Hemisphere
Back to the wind. Low pressure to the LEFT.
98
Friction on the earth surface will cause the surface wind to ____ due to the reduced Coriolis Effect due to reduced wind speed component.
"BACK"
99
List some types of turbulence
- Clear Air Turbulence
- Frictional Turbulence
- Thermal Turbulence
100
What scale relates wind speed and observed sea conditions?
BEAUFORT SCALE
101
List some types of winds
- Sea Breeze
- Land Breeze
- Thermal Wind
102
Describe ANABATIC winds
Warm air blowing up a steep slope or mountainous.
103
Describe KATABATIC winds
Cooler more dense air draining down a slope.
104
The ___ ____ says it is warmer and drier on the "LEE" of high ground.
FOHN EFFECT
105
Coriolis acts to the ____ of direction of travel in the N. Hemisphere
RIGHT
106
What does 24018G30KT represent in METAR?
Wind from 240
| 18kt, gusting up to 30kt
107
What happens to the wind from the late afternoon to overnight?
Wind speed decreases and 'backs'
108
What can be said about the cloud base on the 'lee' of high ground due to the Fohn Effect?
Higher cloud base
109
In the UK, with LP to the East and HP to the West, what will the 'general' wind direction be?
NORTHERLY
110
Clouds are a visible collection of water _____ and/or ___ crystals
Water DROPLETS and/or ICE crystals
111
Clouds typically form when _____ air rises and ______.
MOIST air rises and CONDENSES
112
Clouds form when there is
- Adequate water vapour
- Cloud Condensation Nuclei
- A method for air to be cooled
113
List 'trigger actions' that will lift and cool air
- Convection
- Orographic Uplift
- Convergence
- Mass Ascent
- Turbulence
114
Clouds will disperse due to
- Heating
- Mixing with drier air
- Reduction in Relative Humidity (RH)
115
What is the Latin meaning of "Cirrus"?
Lock or tuft of hair, ringlets or fibrous
116
What is the Latin meaning of "Cumulus"?
Heaped or Piled
117
What is the Latin meaning of "Stratus"?
Flattened or spread out, formed in layers
118
What is the Latin meaning of "Alto"?
High or height
119
What is the Latin meaning of "Nimbus"?
Rain bearing
120
What is the Latin meaning of "Castellanus"?
Castle-like, common base with vertical development
121
What is the Latin meaning of "Lenticular"?
Lens shaped
122
What is the Latin meaning of "Fracto"?
Ragged or broken
123
What is the Latin meaning of "Mammatus"?
Clouds with udder or pouch like patterns
124
Layered cloud will have the prefixes of
Cirro
Alto
Strato
125
Layered cloud will have the suffixes of
Stratus
| Cumulus
126
Precipitation from convective clouds is known as
SHOWERS
127
List the 3 HIGH level LAYERED cloud types
Cirrostratus
Cirrocumulus
Cirrus
128
List the 2 MEDIUM level LAYERED cloud types
Altostratus
| Altocumulus
129
List the 3 LOW level LAYERED cloud types
Stratus
Stratocumulus
Nimbostratus
130
List the 3 CONVECTIVE cloud types
Cumulus
Towering Cumulus
Cumulonimbus
131
What is the designator of CIRRUS clouds
CI
132
What is the designator of CIRROSTRATUS clouds
CS
133
What is the designator of CIRROCUMULUS clouds
CC
134
What is the designator of ALTOCUMULUS clouds
AC
135
What is the designator of ALTOSTRATUS clouds
AS
136
What is the designator of STRATUS clouds
ST
137
What is the designator of NIMBOSTRATUS clouds
NS
138
What is the designator of STRATOCUMULUS clouds
SC
139
What is the designator of CUMULUS clouds
CU
140
What is the designator of TOWERING CUMULUS clouds
TCU
141
What is the designator of CUMULONIMBUS clouds
CB
142
List the 3 major cloud sub-types
Altocumulus Castellanus
Altocumulus Lenticularis
Mammatus
143
What type of cloud is of particular danger to aircraft?
Cumulonimbus (CB)
Associated with Heavy precipitation, Lightning, Thunderstorms and STRONG turbulence.
144
Do TAFs and METARs report the cloud base in AGL or AMSL?
AGL
Due to it being of interest to the specific
145
Cloud bases are reported in what increments of feet?
100s
146
The 'amount' of cloud is measured in _____
OKTAS
147
List the BANDS of OKTAS (inc no. of, name and designation) and the 2 other cloud descriptors.
```
1-2 OKTAS, Few (FEW)
3-4 OKTAS, Scattered (SCT)
5-7 OKTAS, Broken (BKN)
8 OKTAS, Overcast (OVC)
Sky clear (SKC)
Sky obscured (VV//)
```
148
If cloud cover is denoted as FEW, what does this mean?
1-2 OKTAS, Few
149
If cloud cover is denoted as SCT, what does this mean?
3-4 OKTAS, Scattered
150
If cloud cover is denoted as BKN what does this mean?
5-7 OKTAS, Broken
151
If cloud cover is denoted as OVC, what does this mean?
8 OKTAS, Overcast
152
If cloud cover is denoted as SKC, what does this mean?
Sky clear
153
If cloud cover is denoted as VV//, what does this mean?
Sky obscured
154
In the UK, with LP to the East and HP to the West, what will the 'general' wind direction be?
Northerly
155
TRUE or FALSE? Temperature inversions usually make the atmosphere more unstable.
FALSE
Temp inversions make the atmosphere more stable.
156
The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the N. Hemisphere
90 deg to the RIGHT of direction of travel in the N. Hemisphere
157
The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the S. Hemisphere
90 deg to the LEFT of direction of travel in the S. Hemisphere
158
List these clouds in descending order. AC, CC, ST, SC
CC, AC, SC, ST
159
What does BKN070 stand for in a METAR or TAF?
Broken cloud/ 5-7 OKTAS
at 7000 ft
160
List the 6 air masses specific to the UK
```
Tm - Tropical Maritime
Tc - Tropic Continental
Pc - Polar Continental
Pm - Polar Maritime
Am - Arctic Maritime
rPm - Returning Polar Maritime
```
161
An area of HIGH pressure is also known as an _________
ANTI-CYCLONE
162
An area of LOW pressure is also known as a ______
DEPRESSION or CYCLONE
163
Isobars represent lines of _____ ________
EQUAL PRESSURE
164
Describe the LP feature known as a TROUGH (Met)
Isobars extended outwards from an area of low pressure.
Has a sharper 'V' shaped appearance in the isobars.
165
Describe a COL (Met)
Region of almost uniform pressure between two highs and two lows.
166
Describe the HP feature known as a RIDGE (Met)
Isobars extended outwards from an area of high pressure.
Always a rounded shape in the isobars. NEVER a 'V' shape.
167
Name the 3 different types of LOW pressure weather
- THERMAL
- POLAR
- OROGRAPHIC
168
Describe BUYS BALLOT's LAW
N. Hemisphere
Back to the wind. Low pressure to the LEFT.
169
Describe typical conditions with a Tm (Tropical Maritime) air mass in EXPOSED AREAS in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Near sea temp
Hum - Very moist
Stab - Stable
Weather - Low cloud, drizzle, fog
Vis - Often poor with costal fog
```
170
Describe typical conditions with a Tm (Tropical Maritime) air mass in SHELTERED AREAS in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Warm
Hum - Moist
Stab - Stable aloft
Weather - Broken cloud, dry
Vis - Moderate
```
171
Describe typical conditions with a Tc (Tropical Continental) air mass in SUMMER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Very warm or Hot
Hum - Relatively Dry
Stab - Stable becoming unstable in time
Weather - Nil, possible thundery showers in time
Vis - Moderate or poor
```
172
Describe typical conditions with a Tc (Tropical Continental) air mass in WINTER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Average
Hum - Rather moist
Stab - Stable
Weather - Usually cloudy
Vis - Moderate or poor
```
173
Describe typical conditions with a Pc (Polar Continental) air mass in WINTER over LONG SEA TRACKS in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Cold
Hum - Moist in lowest layers
Stab - Unstable
Weather - Rain or snow showers
Vis - Good, poor in showers
```
174
Describe typical conditions with a Pc (Polar Continental) air mass in WINTER over SHORT SEA TRACKS in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Very cold
Hum - Very dry
Stab - Stable
Weather - Very dry
Vis - Moderate to poor
```
175
Describe typical conditions with a Pc (Polar Continental) air mass in SUMMER over LONG SEA TRACKS in the UK.
(Temp, Hum, Stab, Weather, Vis)
Temp - Cool, windward coasts. Warm inland
Hum - Moist near windward coasts. Dry inland
Stab - Stable
Weather - Low cloud, drizzle, mist near windward coasts. Nil inland.
Vis - Poor near windward coasts. Moderate or good inland.
176
Describe typical conditions with a Pc (Polar Continental) air mass in SUMMER over SHORT SEA TRACKS in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Warm
Hum - Dry
Stab - Stable
Weather - Dry
Vis - Moderate or good
```
177
Describe typical conditions with an Am (Arctic Maritime) air mass in SUMMER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Cool
Hum - Fairly moist
Stab - Unstable
Weather - Heavy showers or thunderstorms
Vis - Very good, poor in showers
```
178
Describe typical conditions with an Am (Arctic Maritime) air mass in WINTER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Cold (colder then Pm)
Hum - Moist (not as moist as Pm)
Stab - Unstable
Weather - Heavy showers, sometimes snow, hail and thunder in N. Scot and exposed coasts
Vis - Very good, poor in showers
```
179
Describe typical conditions with an Pm (Polar Maritime) air mass in SUMMER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Cool
Hum - Moist
Stab - Unstable
Weather - Scattered showers
Vis - Good, poor in showers
```
180
Describe typical conditions with an Pm (Polar Maritime) air mass in WINTER in the UK.
(Temp, Hum, Stab, Weather, Vis)
```
Temp - Rather cold
Hum - Moist
Stab - Unstable
Weather - Heavy showers, sometimes with hail and thunder mainly in exposed W and hilly areas.
Vis - Good, poor in showers
```
181
Describe typical conditions with an rPm (Returning Polar Maritime) air mass in the UK ALL YEAR ROUND.
(Temp, Hum, Stab, Weather, Vis)
Temp - Cool (warmer than Pm)
Hum - Moist (Moister than Pm)
Stab - Stable at low levels, unstable aloft
Weather - Variable cloud, possible showers
Vis - Variable
182
A Tm airmass is affecting the UK. What typical weather conditions would you expect in SW England?
Low cloud, mist, drizzle, fog.
183
What conditions would you expect in NW Scotland in a Pm airmass in Winter?
Unstable. SCT/BKN CU TCU CB, SHRA, TSRA
184
What hazard is usually associated with a high pressure?
Poor visibility (haze, mist, fog)
185
What is a front? (Met)
Boundary between 2 air masses of differing temperatures.
186
List the 4 main types of fronts
- Cold
- Warm
- Occluded
- Stationary
187
How is a COLD front depicted?
Blue arrows/triangles
188
How is a WARM front depicted?
Red semi-circles
189
How is an OCCLUDED front depicted?
Alternating Blue arrows/triangles and Red semi-circles. Same side of front line
190
How is a STATIONARY front depicted?
Alternating Blue arrows/triangles and Red semi-circles. Alternating sides of front line
191
When the shapes representing a front are hollow this indicates a _____ front.
UPPER front
192
A weakening front is represented by ......
'X's between the respective shapes
193
A strengthening front is represented by .....
' . 's between the respective shapes
194
Frontolysis is the ______ of a front
WEAKENING
195
Frontogenesis is the ______ of a front
STRENGTHENING
196
What front moves faster? WARM or COLD
COLD
Due to the front being 'steeper' there is less surface friction.
197
How far in front of a warm front might we expect to see some precipitation?
Up to 400km
198
In the N. Hemisphere winds ALWAYS ____ when a front passes overhead
VEER
199
When a WARM front passes over. What will happen to the temperature?
Temperature will increase
200
Describe what happens to the PRESSURE as a WARM front passes over
In advance - Falling pressure
At the passage - Falling pressure
Following passage - Steady
201
Describe what happens to the PRECIPITATION as a WARM front passes over
In advance - Continuous rain (or snow)
At the passage - Minimal or nil
Following passage - Dry or minimal
202
Describe what happens to the VISIBILITY as a WARM front passes over
In advance - Good except in rain (or snow)
At the passage - Poor (often mist or fog)
Following passage - Usually moderate or poor. Mist/fog near windward coasts.
203
Describe what happens to the WIND as a WARM front passes over
In advance - Backing and increasing
At the passage - Sudden veer
Following passage - Fairly steady
204
Describe what happens to the PRESSURE as a COLD front passes over
In advance - Steady then falling
At the passage - Rises
Following passage - Gradual rise
205
Describe what happens to the PRECIPITATION as a COLD front passes over
In advance - Some rain, perhaps thunder
At the passage - Heavy rain (or snow) perhaps thunder or hail.
Following passage - Heavy rain (or snow) for short period, then fine, followed by showers.
206
Describe what happens to the VISIBILITY as a COLD front passes over
In advance - Moderate poor
At the passage - Temporary deterioration followed by rapid improvement
Following passage - Very good but poor in showers
207
Describe what happens to the WIND as a COLD front passes over
In advance - Backing and increasing
At the passage - Sudden veer
Following passage - Backing a little, then fairly steady, then fine followed by showers.
208
In an OCCLUDED front, the ___ front has caught up with the ____ front.
COLD front caught up with the WARM front
209
What are the 2 different types of OCCLUDED fronts?
WARM occlusion - When air ahead of the warm front is COLDER than that of the cold front approaching from behind.
COLD occlusion - When air ahead of the warm front is WARMER than that of the cold front approaching from behind.
210
A _____ occlusion occurs when air ahead of the warm front is COLDER than that of the cold front approaching from behind.
WARM occlusion
211
A _____ occlusion occurs when air ahead of the warm front is WARMER than that of the cold front approaching from behind.
COLD occlusion
212
What air masses are associated with a COLD occlusion?
Pm\Tm/rPm
213
What air masses are associated with a WARM occlusion?
Pm\Tm/Pc
214
What kind of front can be found between two air masses, neither of which is strong enough to replace the other?
STATIONARY front
215
Name and describe the 4 level of ice severity
Trace - Ice is perceptible
Light - 0.5cm in 15-60min
Moderate - 0.5cm in 5-15min
Severe - 0.5cm in <5min
216
Name the 4 different types of icing we can expect to see on an aircraft
- Rime
- Clear/Glaze
- Runback
- Hoar Frost
217
When will RIME icing occur?
Small supercooled water droplets freeze on contact below 0degC.
White or opaque due to air trapped in ice.
218
When will CLEAR/GLAZE icing occur?
Large water drops at temp not far below 0degC and spread while freezing.
Transparent or glass-like surface. Can form horns in opposite direction of flight.
219
When will RUNBACK icing occur?
When the thermal anti-icing system fails to evaporate 100% of water resulting in melt water progressing backwards over surface.
Freezing occurs at or near trailing edge of surfaces.
220
When will HOAR FROSTing occur?
Clear air when the temp of the surface is below the frost-point of the air in contact with it.
221
Icing is most likely to occur between __C and ___C
0C and -20C
222
Vapour, snow or ice in a cloud WILL/WILL NOT generally cause icing on aircraft. (Choose one)
Vapour, snow or ice in a cloud WILL NOT generally cause icing on aircraft.
223
Clouds must contain _____ ____ for ice to form
LIQUID WATER
224
The MOST DANGEROUS type of precipitation for an aircraft is ______ ____
FREZZING RAIN!!!
AVOID AT ALL COSTS.
NO aircraft is certified to fly in moderate to heavy freezing rain.
225
The _____ you fly the greater the amount of icing you can expect to encounter.
FASTER = more icing
226
List some hazards to look out for associated with icing and aircraft
Impact icing - Build up on intakes and filters to engine.
Fuel icing - Water in fuel precipitates out and can cause blockage.
Carburettor icing - Rapid temp drop due to fuel vaporisation and adiabatic cooling.
Turbine or Jet Engine icing - Result in power loss or flame out.
Airframe/Aerofoil icing
Helicopter icing - small amounts have bigger impact
227
What conditions would you expect on the East coast in winter with a Pc airmass? (long sea track)
Cold with snow showers
228
What is usually associated with a thermal low?
Thunderstorms
229
What is another term for a high pressure system?
Anti-cyclone
230
How does the wind direction change on the passage of a front?
Always VEERS (N. Hemispshere)
231
In ascending order, which cloud layers would we encounter on a warm front?
ST, SC, NS, AS, CS, CI
232
What type of occlusion occurs when cool Pm air behind a cold front catches up with a warm front moving in to cold Pc air?
Warm occlusion
233
Which of these clouds is most likely to give severe airframe icing?
NS, AS, CI, ST
NS
Nimbostratus
234
Name the 3 associated LOW systems that might be encountered and describe what we might expect to experience with their presence.
Thermal Low - Can produce heavy Showers and Thunderstorms
Polar Low - Possibility of Thunderstorms in unstable conditions and can produce snow.
Orographic Low - Forms on 'lee'ward side of mountains. Produces little weather but sometimes strong winds and turbulence.
235
Which type of icing is transparent or translucent with a glassy surface?
CLEAR/GLAZE
236
How is MET Visibility defined?
Greatest horizontal distance at which Prominent unlit objects by day and Prominent lit objects by night can be recognised.
237
Name the 2 different types of visibility that can be reported
Prevailing - Max distance covering >0.5 of airfield
Minimum
238
Define PREVAILING VISIBILITY
Maximum visibility covering at least 1/2 of the airfield in contiguous or non-contiguous sectors.
239
When is MIN vis reported? (Mil/Civ)
Mil - If it changes the colour state of the airfield
Civ - If less than 1/2 prevailing and less than 10km
240
How is visibility reported?
4 digit code representing distance in metres
241
What does RVR stand for? (Met)
Runway Visual Range
242
RVR (Runway Visual Range) is only reported when vis is less than ____m.
1500m
243
For RVR (Runway Visual Range) what 3 letters are used to denote the tendency of the visibility?
D - Down or Decreasing
U - Up or Increasing
N - No or No change
244
How is the RVR broken down if represented in a METAR?
R[Runway]/[Vis Distance][Tendency]
Eg - R01L/0400D
245
What term is used when concerned with visibility at a given angle?
SLANT visibility
246
List some things that will obscure visibility
Cloud and precipitation
Spray
Smoke, sand and dust
Haze, fog and mist
Sunlight and moonlight conditions
247
Best visibility occurs when the SUN is ______ you.
BEHIND
248
Best visibility occurs when the MOON is ______ you.
IN FRONT of
249
What is the difference between BLOWING and DRIFTING particulates?
Blowing - Above eye level
Drifting - Below eye level
250
The visibility in clouds and precipitation will depend on ......
Type of cloud
Type of precipitation
Amount of precipitation
251
What is the major difference between Fog, Mist and Haze?
Fog and Mist are associated with moisture.
Haze is associated with dry suspended particulates.
252
What are the approximate visibility limits of Fog(FG), Mist(BR) and Haze(HZ)?
Fog (FG) - <1000m
Mist (BZ) - 1000-10,000m
Haze (HZ) - <10,000m
253
List the different types of Fog
- Advection
- Hill
- Radiation
- Arctic Sea Smoke
254
What is the difference between Fog and Mist?
Fog - Rel Humidity >100%
Mist - Rel Humidity >95%
255
What are the atmospheric conditions for Radiation Fog
```
High rel humidity
Clear night
Light wind
Favourable topography
Moist air
```
256
Radiation fog is dispersed when ......
Winds are high
Insolation (Heating from the sun)
257
What are the necessary conditions for Advection Fog?
Warm moist air moving over cold surface
258
Advection fog is dispersed when ......
Warming of the surface
Change of air mass
Winds increase and turbulence generated
259
What are the necessary conditions for Hill Fog?
Moist stable air forced to rise over high ground then cools and condenses.
260
Hill fog will disperse when ....
The air is dried or change in wind direction/reduction in strength
261
What are the necessary conditions for Arctic Sea Smoke to form?
Cold, dry air moving over much warmer water. With an inversion to trap the fog.
(Can be created in a jar)
262
Arctic sea smoke may disperse when .....
The inversion trapping the moisture collapses.
Difference between the air and the surface is reduced.
263
A solid black line on a synoptic chart means?
A trough
264
A cold front has passed over your station. What type of weather would you expect after the front has cleared?
Showers
265
What conditions would you expect on the East coast in winter with a Polar Continental (Pc) airmass (long sea tracks)?
Cold with snow showers
266
If the ELR was 4 C per 1000ft, what would the stability be?
Unstable
267
Thunderstorms only occur with what type of cloud?
CB - CumuloNimbus
268
List the conditions required for Thunderstorms
- U_____ atmosphere
- T_____ A____
- H___ M______ C_____
- Unstable atmosphere
- Trigger Action
- High Moisture Content
269
Does WARM or COLD air hold more moisture?
WARM
270
List the 4 trigger actions that can cause Thunderstorms?
- Convergence
- Convection
- Mass Ascent
- Orographic Uplift
All trigger actions apart from Turbulence.
271
List the weather patterns which may present a risk of Thunderstorms
- Thermal Low (Lots of air rising quickly)
- Troughs
- Active Cold Fronts (A strong front lots of activity)
- Occlusions
272
Describe a THERMAL LOW system
An area of low atmospheric pressure near the surface resulting from heating of the lower troposphere and the subsequent lifting of isobaric surfaces and divergence of air aloft.
273
Describe a POLAR LOW system
A small but intense cyclone that forms in cold polar air advected over warmer water.
274
Describe an OROGRAPHIC LOW system
-
275
What are the 3 stages of Thunderstorms
Building
Mature
Dissipating
276
Describe the BUILDING stage of a Thunderstorm
- Small CU begin to grow
- Strong vertical updraughts (up to 30m/s)
- Inflow from base and sides of cell
- Can take 15-20 mins
- No precipitation
277
Describe the MATURING stage of a Thunderstorm
- Precipitation falling at base (rain or hail)
- Cloud tops extend above 0degC level
- Downdraughts drag cold air down
- Drop in temp below cloud
- Downdraught acceleration forms gust front spreading outwards.
- Anvil clouds form due to large amount of ice crystals.
278
Describe the DISSIPATING stage of a Thunderstorm
- Storm has used up supply of local moisture.
- Cloud top begins to spread laterally.
- Downdraught abates.
- Cloud may persist for 2 to 3 hours.
279
List the 4 types of Thunderstorms
- Single Cell
- Multicell
- Multicell -Squall Line
- Supercell
280
Describe a SINGLE CELL Thunderstorm
- One time updraught and downdraught
- Short lived
- May produce hail and gusty wind
- Potentially for multiple single cells in an area
281
Describe a MULTICELL Thunderstorm
- Each cell acts like a single cell
- As each cell matures it is carried downwind
- New cells tend to form in place of the preceding cell
282
Describe a MULTICELL-SQUALL LINE Thunderstorm
- Line of Thunderstorms
- Can last for many hours
- New cells form continuously at leading edge
- May produce large hail and strong outflow winds which move rapidly ahead of system
- Often has a shelf cloud along leading edge
283
Describe a SUPERCELL Thunderstorm
- Most common in N. America, rare in W. Europe.
- Rotating updraughts
- Type of single cell thunderstorms
- Can persist for many hours
- Highly organised storms
- Can produce hail, strong winds and tornadoes
- Entire cloud rotates
- Exhibit wall clouds - isolated lower clouds below the rain-free base and below main storm tower.
284
Name the 3 different groups of SUPERCELL Thunderstorm
- Low Precipitation
- Classic
- High Precipitation
285
What Mnemonic do we use for the Hazards of Thunderstorms?
WHISTLE
286
What does the Mnemonic WHISTLE represent when it comes to Hazards of Thunderstorms?
```
W - Weather (Heavy Precip)
H - Hail
I - Icing
S - Squall Line
T - Turbulence (Rapid pressure change, Downbursts, Strong Winds)
L - Lightning
E - Electricity (static)
```
287
List some Indicators of Thunderstorms
- Cloud (Rapidly building TCU, CB, AC Castellanus, Mammatus)
- Precipitation (Hail, Rain or Snow)
- Radar Image/ Radio Crackle
- Lightning
- Static Elec
- St Elmo's Fire
- Visible discharge of static electricity
288
What does METAR stand for?
METeorological Aerodrome Report
289
What does TAF stand for?
Terminal Airfield Report
290
What are the first 4 components of a METAR? (not including 'METAR' at the start)
ICAO Aerodrome code
Day/Time
Wind
Prevailing Vis
291
What are the 3-6 components of a METAR? (not including 'METAR' at the start)
Wind
Prevailing Vis
Present Weather
Cloud
292
What are the 5-8 components of a METAR? (not including 'METAR' at the start)
Present Weather
Cloud
Temp/Dewpoint
Pressure [QNH]
293
List all the components of a METAR in order
```
ICAO Aerodrome code
Day/Time
Wind
Prevailing Vis
Present Weather
Cloud
Temp/Dewpoint
Pressure [QNH]
```
294
What type of occlusion occurs when cold Pm air behind a cold front catches up with a warm front with cold rPm air ahead?
COLD occlusion
295
At what temperature is icing most likely to occur?
0 to -20C
296
What does SCT200 stand for in a METAR or TAF?
3-4 OKTAS at 20,000ft
297
What does 05/05 mean in a METAR?
Temp 5C, Dewpoint 5C, Rel Hum 100
298
What does 24018G30KT represent in a METAR?
Wind coming from 240, 18 kt with gusts up to 30 kt.
299
If the visibility is 1200 M and the RH is 98%, what weather would be reported?
Mist
>1000m so NOT fog
RH cut-off for MIST = 95%
300
What does the letter 'I' in the mnemonic 'WHISTLE' stand for?
ICING
301
Which of the following is an indicator of Thunderstorms activity?
- Drizzle
- Turbulence
- AC Lenticularis
- St Elmo's Fire
St Elmo's Fire
302
How long are TH (Thunderstorms) classed as 'present weather' for in a METAR?
10 mins
303
How long is a METAR trend valid for?
2 hours
304
How often are TAFs issued at a Military Airfield?
Every 3 hours
305
In TAFs, what does the change group BECMG indicate?
A gradual but permanent change in one or more elements of the forecast, during the time period shown.
306
Where is the Tropopause highest?
Near Equator or Near the Poles
Near the Equator
307
True or False?
Warm air can hold more moisture than cold air?
TRUE
308
What type of precipitation is only associated with CBs?
Showers
Snow
Hail
Drizzle
HAIL
309
The Coriolis effect acts to the ____ in the S. Hemisphere
LEFT
310
What 3 weather phenomena operate under the '10 min rule' for present weather?
THunderstorms
SQualls
Funnel Cloud
311
QNH in a METAR is ALWAYS rounded ____ for safety
Rounded DOWN
312
TEMPO represents a ____ condition.
What defines TEMPO?
TEMPORARY condition
- No more than 1/2 of the associated time.
- No more than 1 hr at a time.
313
Think about the 3 Cell model.
What are the names of the 3 cells?
Polar
Ferrell
Hadley
314
What is the name of the Great Circle on the Earth which has the highest amount of thermal heating?
Thermal Equator
315
The winds converging around the Equator from N&S Hadley zones ay also be called the ...
Intertropical Convergence Zone - ITCZ
316
In the ITCZ what type of cloud/weather might we see more often?
CBs and convective weather.
317
The Coriolis Effect is strongest where?
Near the Poles
318
Name the 6 climactic region types
- P___
- T_________
- M_________
- A___/D____
- T______
- M_________
- Polar
- Temperate
- Mediterranean
- Arid/Desert
- Tropical
- Mountainous
319
Name the 3 main parts of a tropical cyclone
- Eye
- Eye wall
- Rain bands
320
What are the conditions for GREEN colours state or better?
3700-5000m vis
1500ft cloud base
321
Requirements for Tropical Storm Formation
>26C, Light Winds, 5-15 deg from Equator
322
What direction are trade winds in the N.Hemisphere?
NE'ly
323
The QNH is always rounded _____
DOWN
This is done for safety as your altimeter will read lower than you actually are.
