Meteorology Flashcards
1
Q
What temperature is the isothermal layer?
A
-56.5 degrees
2
Q
Where is the isothermal layer?
A
Stratosphere
3
Q
What temperature do we find in the mesosphere?
A
-90 degrees
4
Q
Why does temperature increase as we climb in the stratosphere?
A
High concentration of ozone
Ozone absorbs large amounts of solar radiation
Layer heats as a result
5
Q
What is the ISA lapse rate?
A
1.98 degrees per 1000 feet to 36090ft
6
Q
What is ISA pressure?
A
1013.25 hPa
29.92 in Hg
7
Q
What is an isobar?
A
Line of equal pressure
8
Q
Earth pressure density?
A
1.225kg/m3
Or
1225g/m3
9
Q
What is the specific heat capacity of water?
A
1 calorie / gram
10
Q
What is the specific heat capacity of air?
A
0.3 calorie / gram
11
Q
What is the area of lower pressure at the equator?
A
Equatorial trough or equatorial low
12
Q
What is the area around 30 degrees north and south of the equator called?
A
Sub tropical high
13
Q
What is the area at around 60 degrees north and south latitude?
A
Polar high
14
Q
What is the name of the cell between the equator and 30 degrees NORTH
A
Northern Hadley cell
15
Q
What is the name of the cell between the equator and 30 degrees SOUTH
A
Southern Hadley cell
16
Q
What is the name of the cell that appears between 30 and 60 degrees latitude, both north and south
A
Mid latitude cell
17
Q
What is the name of the cell between the poles and 60 degrees?
A
Polar cell
18
Q
Weather systems associated with equatorial/monsoonal trough?
A
Complex low pressure systems
19
Q
How is water vapour formed?
A
Evaporation due to solar radiation of moist ground or water surfaces
20
Q
What does relative humidity depend on?
A
Air temperature
21
Q
What is a temperature inversion?
A
When temperature does not decrease normally as we increase height
22
Q
What is a temperature inversion indicative of?
A
A very stable atmosphere
23
Q
What are the types of temperature inversions?
A
Radiation
Subsidence
Frontal
24
Q
What can a radiation inversion also be called?
A
Surface inversion
Nocturnal inversion
25
Are radiation inversions likely to form on cloudy or windy nights?
No
26
What are the contributors to thermal turbulence?
Solar radiation
Frontal activity
Inversions
27
What is VB?
Best turbulence airspeed
28
What is wind shear
The change of the wind speed and or direction over a short distance resulting in a speed variation bigger than 10 knots
29
Where is low level wind shear?
Along the runway
Along the departure and approach flight paths below 1600 feet
30
Define environmental lapse rate
How quickly the air is cooling as altitude is increased
31
What is the ISA ELR?
1.98 degrees per 1000 ft
2 degrees for calculations
32
What is the ACTUAL environmental lapse rate?
The actual vertical temperature profile for the atmosphere over a given point at a specific time during the day. Changes day to day
33
What is the dry adiabatic lapse rate?
3 degrees per 1000ft
34
What is the saturated adiabatic lapse rate?
1.5 degrees per 1000ft
35
What kind of force is the Coriolis force?
Deviating force
36
Which way does Coriolis push the airflow in the southern hemisphere?
Turns air flow to the left
37
Does a stronger wind make Coriolis stronger or weaker?
Stronger
38
What is gradient wind a combination of?
PGF and Coriolis force
39
What is PGF?
Pressure gradient force
40
What is pressure gradient force?
An initiating force that initiates a flow of air from a high to a low. It acts at right angles to the isobar
41
What is the upper limit of surface winds?
3000 feet AGL
42
Which way does a high pressure system rotate in the southern hemisphere?
Anti clockwise
43
Surface wind vs gradient wind over land?
Veer 30 degrees
1/3 wind speed remaining of gradient wind
44
Surface wind vs gradient wind over water?
Veers 10 degrees
2/3 wind speed remaining of gradient wind
45
How to identify a ridge?
Isobars stretching out from a high
46
What is a squall?
Sudden wind speed increase lasting at least a minute
47
What is a gust?
Sudden wind speed increase but only lasting a few seconds
48
What is a col area?
An area of almost constant pressure between two highs and two lows
49
What weather could be expected in a col area?
Light and variable winds
Possible fog in winter
Possible thunderstorms in summer
50
How many oktas is few
1-2 oktas
51
How many oktas is scattered?
3-4 oktas
52
How many oktas is broken?
5-7 oktas
53
When is nil significant cloud used?
No cloud below 5000ft
No CB or TCU at any height in the vicinity
54
What level is high level cloud?
Base above 18000ft
55
What level is mid level cloud?
Base 8000-18000 feet
56
What are high level clouds?
Cirrus
Cirrostratus
Cirrocumulus
57
What are mid level clouds?
Altostratus
Altocumulus
58
What are low level clouds?
Stratus
Cumulus
Nimbostratus
Stratocumulus
Cumulonimbus
Towering cumulus
59
What precipitation does nimbostratus cause?
Heavy, continuous rain
60
What precipitation comes from altostratus?
Intermittent or continuous rain or snow
61
What determines absolute atmosphere stability?
Actual ELR less than 1.5 degrees per 1000ft
62
What determines an unstable atmosphere?
Actual ELR more than 3 degrees per 1000ft
63
What is neutral atmospheric stability?
The parcel of air is the same temperature as the surrounding air, resisting the tendency to rise
64
What are the diurnal variations in wind speed?
Lowest wind speed around dawn
Maximum wind around 1500
65
Diurnal wind variation - night to day
Surface wind increase
Back anticlockwise
66
Diurnal wind variation - day to night
Surface wind decrease
Veer clockwise
67
How high is the effect of sea breeze?
1000ft above the surface
68
When is a sea breeze strongest?
Mid afternoon
69
When is the land breeze the strongest?
Early hours of the morning (dawn)
70
What can reinforce a land breeze?
Katabatic winds
71
Where are rotors found?
Leeward side
Below the crest of the mountain
In the crest of the wave
72
What is orographic lifting?
Moist air forced up against a mountain
73
What is Fohn wind?
Moist air forced against a mountain range
As the air is forced up it adiabatically cools to dewpoint and clouds form on the upwind side of the mountain. Rain falls upwind side.
After rain moisture reduces it descends dry and is warmed - the Fohn wind
74
Characteristics of a low level jet
Strongest in the early morning
Most prevalent in winter
Wind speed up to 70 knots
Usually southern direction
75
What is the full name of lenticular cloud?
Altocumulus lenticularis
76
Where are lenticular clouds found?
At the crest, on the Lee side of the mountain
77
What wind speed causes mountain waves?
Faster than 20knots perpendicular or approximately so to the mountain
78
What are the four classifications of air mass?
Tropical maritime
Tropical continental
Polar maritime
Polar continental
79
What is the definition of meteorological visibility?
The greatest horizontal distance at which a person can identify a dark object of suitable dimensions on a relatively dark background
80
What is reported visibility?
The horizontal visibility as reported from an accredited weather observer on the ground
81
What is flight visibility?
Horizontal visibility as observed by the pilot from the cockpit when in flight
82
What is slant visibility?
Air to ground visibility from an angle as observed by the pilot when in flight
83
When is daylight visibility worst?
Dawn and dusk
84
What measure is vertical visibility measured in?
Feet
85
What is runway visual range?
The maximum distance the runway can be seen from the average eye level of the pilot at touchdown
86
What is the difference between how clouds and fog/mist are formed?
Clouds are formed through convection of air parcels
Fog/mist formed through conduction with a cold surface
87
What visibility defines fog?
Less than 1000m
88
What visibility defines mist?
At or more than 1000 metres
89
What are the types of fog?
Radiation
Advection
Frontal
Steam
90
Conditions for radiation fog
Clear skies
Light winds (<5 knots)
Humid air
91
Why does radiation fog initially thicken?
Mixing by solar radiation
92
What is advection fog?
Warm humid air passing horizontally over a cold surface (ground or water)
93
How is advection fog formed?
Warm humid air flows across a cold surface, cooled via conduction and when cooled to dew point, forms fog
94
How can advection fog be dissipated?
Stronger wind (>15 knots)
Reduced humidity through deposition of moisture onto vegetation
Change in wind direction stops the feeding of moist air
95
How is frontal fog formed?
Rain falls through the boundary of a warm front, saturating the air below. As the air ahead of the front is colder, it cools the saturated air to dewpoint, forming fog or low level stratus cloud ahead of the front
96
What is steam fog?
Cold moist air flowing over warmer water and evaporation from the water surface causes the cold air above to be saturated
97
What are the three conditions required for thunderstorm formation?
Conditionally stable atmosphere (high enough ELR to aid the rise of air parcels)
Abundant moisture
A trigger to initiate air rising
98
What are the triggers initiating the rising of air for a thunderstorm?
Solar radiation
Orographic lifting
Surface convergence
Frontal activity
99
What are the stages of a thunderstorm life cycle?
Cumulus stage
Mature stage
Dissipating stage
100
If required to fly around a thunderstorm which way should you go?
Upwind of the cell
101
How far a distance should you avoid CB’s?
20nm
102
What conditions are suitable for clear ice?
Outside temperature of 0 degrees to minus 15 degrees
Large supercooled droplets
103
What conditions are suitable for rime ice?
OAT of minus 10 to minus 20
Smaller supercooled water droplets
104
What cloud is suitable for rime ice?
Stratiform
Thin AS
Tops of CU
105
What cloud is suitable for clear ice?
Cumuliform or nimbostratus (convective)
106
How does rime ice form?
Freezes on impact
107
How does clear ice form?
Does not freeze on impact but spreads rearward
108
What are the three different types of icing?
Hoar frost
Rime ice
Clear ice
109
What is hoar frost?
Water vapour molecules that come into contact with surfaces that are already below freezing temperature
110
What ice is large water droplets more likely to create?
Clear ice
111
What ice are smaller water droplets likely to cause?
Rime ice
112
Where is the isotherm?
The stratosphere
113
What is the name of the box that thermometers are kept in at an airport?
Stevenson Screen
114
How does the earth emit heat back into the atmosphere?
Long wave terrestrial radiation
115
What is the transformation from vapour to ice?
Deposition
116
What is the transformation from ice to vapour?
Sublimation
117
What does a temperature inversion indicate?
A very stable atmosphere
118
What inversion is mostly associated with high pressure systems?
Subsidence inversion
119
To avoid wake turbulence in flight you should
Fly above and upwind of the path of the heavier aircraft
120
What is a ridge?
A finger shaped extension of a high pressure system
121
What is a trough?
Finger shaped extension of a low pressure system
122
What is Buy Ballot’s law?
In the southern hemisphere by facing with your back to the wind the low pressure system will be on your right
123
What conditions are generally needed for thermals?
Strong solar radiation
Relatively dry air
124
Where are clouds formed after orographic lifting?
Upwind side of the mountain range
125
What level are low level jets usually found?
Below 3000ft above the peaks of the mountain range
126
What effects are in a low level jet?
Strong windshear
Strong turbulence
127
What wind speed creates mountain waves?
Faster than 20 knots
128
What height must a mountain be to be affected by mountain waves?
Minimum of 1000ft above surrounding elevation
129
Where are the mountain waves created?
In the air on the Lee side
130
What kind of cloud is lenticular cloud characterised as?
Stationary cloud
131
What is a Kelvin-Helmholtz Wave cloud?
Indicative of mountain wave activity
Indicative of severe vertical windshear
132
Where are rotor zones found?
On the Lee side of the mountain below the crest
133
What are the dangers associated with mountain waves and rotor zones
Severe windshear and severe turbulence
134
How do you mitigate risks of mountain waves and rotor zones?
Fly above and higher than the mountain range - at least 1000ft above the highest elevation
Fly oblique
135
What radius does a TAF cover?
8km of the ARP
136
How high does a GAF go?
10000ft
137
What is the definition of a tropical cyclone?
Small, intense low pressure systems over warm oceans
138
What band of latitude do cyclones generally form in?
5-15 degrees south
139
What water temperature does a cyclone need to form?
Water above 26.5 degrees
140
What is tropical cyclone season?
November to April
141
What are the four stages of a tropical cyclone?
Formative
Immature
Mature
Decaying
142
Where is the strongest wind found in a cyclone?
Front left quadrant
143
Why does a cyclone decay heading towards the equator?
Coriolis force is not sufficient to maintain the rotation
144
Why does a cyclone decay heading south?
The water is too cool to continue feeding water vapour into the cyclone
145
What’s the surface pressure of the centre of a cyclone?
Approximately 950 hPa
146
What wind speed is gale force?
34 knots or greater
147
What diameter are tornados?
Generally less than 300m
148
What is a funnel cloud?
Tornado that does not touch the ground but is still spiralling the same way
149
What cloud does base apply to for alternate?
Few, scattered
150
What cloud does ceiling apply to for alternate?
Broken, overcast
151
Which way does the pressure gradient force act?
Perpendicular to the isobars
