Weather Flashcards
(123 cards)
1
Q
What is the composition of the Atmophere?
A
78% Nitrogen, 21% oxygen, 1% other gasses
2
Q
Height of the troposphere?
A
55K over equator, 28k over poles, 36k over USA
3
Q
Where is standard lapse rate?
A
Troposphere
4
Q
Where is isothermal lapse rate?
A
Tropopause
5
Q
Where is inversion lapse rate?
A
Stratosphere
6
Q
Where is the jet stream?
A
Just below tropopause
7
Q
Average height of tropopause in USA?
A
36k
8
Q
Characteristics of stratosphere
A
Above tropopause
has temp inversion
flying is smooth with excellent vis
9
Q
standard temp lapse rate
A
2*c per 1000’
10
Q
Average PSI at sea level standard day
A
14.7
11
Q
How does pressure change as alt increases?
A
always decreases
12
Q
2 units of atmospheric pressure
A
in of hg or millibars 15c or 59f
13
Q
Station pressure definition
A
atmospheric pressure measured directly at an airfield or other weather station
14
Q
sea level pressure
A
pressure measured if the station would be at mean sea level
15
Q
what are ridges
A
high pressure good wx
16
Q
what are troughs
A
low px bad wx
17
Q
what is the adjustable part of an altimeter called
A
kollsman window
18
Q
Temperature affect altimeter error how?
A
cold air then normal plane is lower
warm air than normal plane is higher
19
Q
Temp dev on altimeter error
A
11*C causes 4% Error
20
Q
Pressure change on altimeter error
A
high to low lookout below
low to high plenty of sky
21
Q
Indicated altitude definition
A
alt as read on altimeter
22
Q
absolute altitude
A
agl alt
23
Q
true alt
A
alt referenced to mean sea level
24
Q
pressure alt
A
alt above a standard datum plane
25
density alt
pressure alt corrected for non standard temperature deviations
26
What is density alt measure
aircraft performance
27
pennant
single barb
half barb speeds
50
10
5
28
parts of station model
wind direction and speed
temp and dew point
sea level pressure
pressure change
sky cover
29
isobar definition
lines of equal pressure
30
how far are isobars spaced on chart
4 millibars
31
close isobars means what for winds and illustrate what
the pressure gradient force, the closer the isobars are together the higher they will be and higher wind
32
Gradient winds definition
winds flow parallel to isobars due to coriolis force and turns air to the right
found above 2000'
33
surface winds definition
found below 2000 agl friction, pressure gradient, coriolis all balance and winds flow at 45 across isobars
34
Average height of jet stream
30,000 ft
35
average wind speeds for jet stream
100-150 but can be as high as 250
36
size of jet stream
1000-3000 miles long
100-400 miles wide
3000-7000 ft deep
37
Local winds definition
systems tens of miles across to long thin geographic areas
like mountain ranges
38
what is sea breeze
land heats fast, air rises and cold ocean air moves in to fill it 15-20
39
land breeze
land cools faster than water and air flows from land to ocean at night
40
valley wind
day mountain slopes warmed and warms air which begins to rise. cool air settles down to the valley floor and pushes warm air up the mountain
41
mountain wind
at night the cool mountain cools surrounding air which flows downhill
42
dew point definition
temp where saturation occurs
43
Relative humidity def
percent of saturation of air compared to max amount the air can hold at that temp
44
3 characteristics of precipitation
showers, continuous, intermittant
45
showers definitions
starts, stops, changes intensity or sky conditions rapidly, associated with cumuliform clouds
46
continuous definition
stady and changes intensity gradually, associated with stratiform clouds
47
intermittent def
stops and starts at least once during the hour
48
types of precipitation
drizzle, rain, frozen
49
low clouds def
surface to 6500 agl
can produce faster icing
50
middle clouds
form between 6500 to 20K
prefix alto
vis can be poor icing common
51
high clouds
20000 to 40K
cirro or contain word cirrus
no precip or icing hazard
52
CB clouds
thunderstorms with heavy rain and mod turbulence
53
Nimbostratus
heavy steady rain
54
What is stable atmosphere
cold air lifted and then sinks back down to the ground
55
What is unstable atmosphere
warm air lifted and continues to rise when lifting action removed
56
Neutral stability
air that has the same temp as surrounding air remains at the point where lifting was removed
57
4 methods of lifting
convergent
frontal
orographic
thermal
58
flight conditions for stable atmosphere
cloud type - stratus
turbulence - smooth
visibility - poor
winds - steady
precip - steady
icing - rime
59
Flight conditions for unstable atmosphere
cloud type - Cumulus
turbulence - rough
visibility - good
winds - gusty
precip - showery
icing - clear
60
Air mass definition
large body of air that has essentially uniform temp and moisture in horizontal plane
61
air masses are named by
moisture content, location, and temp with location most important
62
front definition
discontinuity that forms between two adjacent air masses
63
weather on either side of front is called
frontal zone
64
3 characteristics of fronts
always in trough of low px
cold fronts move faster than warm
frontal passage accompanied by 90* shift in wind
65
shallow fronts
produce cloudiness and steady precip
66
steep fronts
produce showers and narrow bands of cloudiness
67
cold fronts
produce thunderstorms
wind shifts from SW to NW
68
Squall lines
line of violent thunderstorms dotted and dashed purple lines
50-300 miles ahead of cold front parallel
69
Warm fronts
Warm air overrides cold air causes cloudiness and steady precip up to 500-700 miles ahead of surface front
winds shift from SE to SW
70
Stationary front
wind has 180 shift
71
Occluded front
cold front overtakes warm front
type depends on which temp stays on ground
180* wind shift
most severe weather 100 miles south to 300 north of frontal intersection
72
Turbulence intensity classifications
light
mod
severe
extreme
73
Duration of turbulence
occasional less than 1/3
intermittent- 1/3 to 2/3
continuous- more than 2/3
74
4 Causes of turbulence
thermal
mechanical
frontal
wind sheer
75
Clear air turbulence
usually in jet stream although any wind shear is CAT
76
Thermal turb
also called convective
77
mechanical turb
caused by passage of wind over obstructions
78
mountain wave turb
winds blowing perp to mountain form standing waves
best determined by clouds
79
rotor cloud
downwind and parallel to range
80
cap cloud
covers mountain and dows not move
81
lenticular cloud
form on leeward side of mountain from standing waves
82
mountain wave turbulence intensities
50 knots at peak - extreme
up to 150 miles downwind - severe
up to 300 miles downwind - moderate
83
how to avoid mountain wave turbulence
circumnavigate
fly 50% higher than peak
avoid all clouds
approach range at 45*
84
2 main groups of icing
structural and engine
85
icing types structural
clear, rime, mixed, frost
86
engine icing
compressor icing and induction icing
87
icing requirements
visible moisture
supercooled water
air and skin temp below freezing
88
clear icing characteristics
0 to -10*c
large drops freeze slowly and assume shape of airfoil
cumulus clouds and unstable conditions
89
rime icing characteristics
-10 to -20*C
small drops freeze instantly
statiform clouds
90
mixed icing
combination of clear and rime
-8 to -15*c
91
Frontal icing warm front
rime icing
low rate of accumulation and stratoform clouds
92
frontal icing cold fronts
cumuliform clouds
clear icing
high rate of accumulation
93
frontal icing occluded front
mixed clouds
mixed icing rime clear and mixed
rapid and heavy accumulation
94
aerodynamic effects of icing
changes stall AOA
95
Performance effects of icing
decreases lift thrust range
increases drag weight fuel consumption and stall speed
96
Other effects of icing
pitot static system
inhibits control surface movement and antenna transmission
97
Icing conditions
visible moisture
0 to -20*C
98
How to get out of icing
climb or descend, anti ice or deice
99
Types of antiice or deice equip
fluid
mechanical
heat
100
fluid deice
lowers freezing point of water
101
mechanical deice
rubber bladders on leading edge of airfoils
102
Icing intensities reported by PIREP
trace
light
mod
severe
103
prevailing visibility def
equaled or exceeded throughout over half of the horizontal circle, in statute miles and need not be continous
104
slant range vis
distance on final which runway was in sight
must be reported on PIREP
105
Runway visual range RVR
distance seen looking down runway from approach end
reported in feet or meters
106
Obscurring phenomena
reported when visibility less than 6 miles
fog
haze
smoke
rain
107
sky coverage
reported in eights
108
ceiling
lowest broken or overcast layer in AGL
109
Fog Definition
visible layer of moisture with vis less than 5/8 mile
110
3 requirements for thunderstorm formation
moisture
unstable air
lifting action
111
Thunderstorm hazards
turbulence
gust front
roll and wall clouds (wind shear)
hail
lightning
tornado
112
microburst size
only 1/4 to 2.5 miles wide
5-10 minutes
from cumuliform cloud
113
how to detect microburst
virga
rain shaft
severe thunderstorms
radar
low level wind shear alert system
pirep
114
surface analysis charts
depict pressure centers, fronts, precip lines, not a forcast
115
forecast prognosis charts
predicts positions of fronts, pressure centers, forecast wx
116
nexrad radar
detects showers, tornados, hail size and location, areas of wind shear, gust fronts, microbursts
117
satellite imagery types
infrared and visible
118
sigmets
advise of potentially hazardous significant meteorological information other than convective activity
119
convective sigmets
used only for thunderstorms, tornados, hail
120
airmets
conditions of lower intensity than sigmets
121
3 types of airmets
sierra (seen)
Tango (turbulence)
zulu (icing)
122
When is atc required to solicit pirep
ceiling at or below 5000'
vis less than 5 miles
thunderstorms
light icing or greater
wind shear
mod turbulence
123
when are pilots required to submit pirep
unusual forecast wx
wx on ifr
missed approach due to wx
wind shear
volcanic activity
laser activity
birds
