Chapter 4 Flashcards
1
Q
How many knots does a full sock indicate?
A
15 knots
2
Q
When is a Gust reported?
A
A gust is reported when there is at least 10 kn variation between peaks and lulls within the last 10 minutes
3
Q
What does the letter V stand for in a metar?
A
Variable of the wind direction
4
Q
Can you assume that there is no clouds above 15,000 feet if it says CLR IS?
A
No, there could be a cloud layer above it
5
Q
What happens if the temperature and dew point are close together?
A
Less visibility
6
Q
Low-pressure winds go in what direction?
A
Counterclockwise
7
Q
Winds are always ________ to isobars ?
A
Parallel
8
Q
Velocity = ?
A
Wind speed
9
Q
What instrument do you use to measure wind?
A
Anemometer
10
Q
What is the definition of a Lull?
A
Between the gust and your steady
11
Q
What three forces effect wind or air motion?
A
Pressure gradient
Coriolis force
Friction force
12
Q
Where will you find the boundary layer?
A
2,000 AGL
13
Q
At what place do you find most of the friction or frequent turbulence?
A
The boundary layer
14
Q
Where will you find a deeper boundary level?
A
higher wind speeds
15
Q
A seabreeze comes from what direction?
A
Wind coming from the sea
16
Q
What direction does the wind come from during a land breeze?
A
Wind comes from the land
17
Q
At what time will you see a land breeze?
A
Night
18
Q
At what time will you see a seabreeze
A
Day
19
Q
When is there a frontal passage?
A
A frontal passage occurs during a change in pressure.
20
Q
When pressure decreases and then increases what does this represent?
A
A frontal passage
21
Q
“VV” stands for ?
A
Vertical visibility
22
Q
Is vertical visibility considered a ceiling?
A
Yes
23
Q
In the southern hemisphere wind rotates in what direction?
A
90° clockwise
24
Q
In the northern hemisphere what rotates in what direction?
A
90° counterclockwise
25
What direction does a cyclone flow?
Counterclockwise to the right
26
what direction does an anti-cyclone flow?
Clockwise to the left
27
What force makes the wind want to go outward 90° to the right in the northern hemisphere and 90° left in the Southern Hemisphere?
Coriolis effect
28
If you are observing frontal activity what type of chart are you looking at?
A surface chart
29
Why is the wind skewed in surface charts?
Because of friction
30
When two air masses come together energy transfers creating what?
Weather
31
What does Coriolis effect need to work?
Wind
32
If the wind speed is zero, what is Coriolis speed at?
Zero
33
Friction is caused by high-pressure wanting to go ______ and low pressure wanting to go ________.
Outward and inward
34
What type of performance do you get with windshear?
An increase in performance
35
What type of changes do you see in wind sheer?
Instantaneous
36
On approach if you have a tailwind what kind of performance will you have?
A decrease in performance
37
If you have a headwind on approach what kind of performance will you have?
An increase in performance
38
Where is the lull in this metar :
33010G24K
10G
39
At what degree does variable wind have to be at to be present on a metar?
Greater than or equal to 60 degrees
40
What are the two causes of wind?
Pressure gradient and wind variation
41
What are the two types of wind?
Horizontal and vertical
42
Are cold fronts gradual or steep?
Steep
43
What is it called when air is being sucked up due to low-pressure
Convergence
44
What is it called when air is being sucked down due to high pressure
Divergence
45
What is it called when warm air moves upward over the cold air?
Frontal lifting
46
Gravity wave motions are typical in what state of air neutral, unstable or stable?
Stable
47
What is dry adiabatic process?
Cooling by expansion and warming by compressing
48
What is the temperature lapse rate for dry adiabatic process?
3° per thousand feet
49
Is sounding reality or theory?
Reality
50
What is Term sounding ?
A measurement meteorological conditions between the ground and some higher level of atmosphere
51
What is the result of temperature inversion?
When warmer air goes up
52
If LR>DALR what state is the air in stable or unstable ?
Unstable ,absolute
53
What state is the air in for a cumulus cloud ?
Unstable
54
What state is the air in a stratus cloud?
Stable air
55
If you are in a field and there is a low pressure system and the wind is hitting your back what direction is the low-pressure?
The low-pressure is to the left
56
Wind direction provided by weather observers will be oriented to_______ North
True
57
When direction provided by air traffic controllers will be oriented to ______north
Magnetic
58
The average speed of the wind is referred to as
Sustained speed
59
What kind of wind speed must occur to be reported as a gust________
At least A-10 not variation between peaks and Lulls
60
What change of wind speed must occur to be reported as a squall_________
Sudden increase of at least 60 kn to a sustained speed of 22 kn or more
61
What does VRB mean relative to wind direction?
Variable
62
Interpret this wind information-what is the wind direction 020V090?
020 variable 090
63
Interpret this wind information-what is the wind speed 15G27KT
Wind 15 kn gusting 27 kn
64
What three things make the wind "blow"?
Coriolis effect, Friction force, pressure gradient force
65
A pressure gradient is_____
Difference in pressure between two points
66
At what point on the planet is Coriolis force Least significant ?
The equator
67
At what point on the planet is Coriolis force most significant?
The poles
68
Must air move for Coriolis forced to take effect?
Yes
69
What Coriolis force affect a strong win more than a light wind ?
Yes
70
Geostrophic balance refers to the balance of what two forces?
Pressure gradient force and Coriolis force
71
What is Buys-Ballot's law ?
With the wind at your back, below is always on your left ( in the northern hemisphere)
72
In the northern hemisphere, air moves_______, around the center of low pressure,_________ around the Center of high-pressure
Counterclockwise and clockwise
73
Why doesn't Geostrophic balance occur in small-scale circulations?
Pressure gradient force is much greater than Coriolis force
74
On a 500 my constant pressure chart
A. What does the direction of the line out of the circle mean
Wind direction
75
On a 500 mb Constant pressure chart what does one wind Barb equal
10 knots
76
On a 500 mb constant pressure chart
C. What does 1028 mean?
Pressure is 1028 millibars
77
On a 500 mb Constant pressure chart
D. Relative to the circle, where would you look for temperature data
Top left side of the data block
78
On a 500 MB Constant pressure chart
E. What kind of temperature would that be
Centigrade
79
On a 500 MB Constant pressure chart
F. Relative to the circle, where would you look for pressure Data
To the right side of the data block
80
On a 500 MB Constant pressure chart
G. What kind of pressure would that be
Millibars of pressure
81
When the friction over the earths surface equates to__________ Aircraft drag
Form or surface
82
At what altitude does wind begin to change from parallels to our isobars?
2000 feet AGL
83
In the northern hemisphere, compared to wind altitude, wind at surface shifts which Way, (left or right)?
Left
84
Which wind is usually stronger- surface wind or wind aloft?
Winds aloft
85
Centripetal acceleration refers to what force?
Centrifugal force
86
Cyclostrophic balance is the balance of what two forces
Pressure gradient force and centrifugal force
87
What balance does a tornado or present?
Cyclostrophic balance
88
The two major lateral motions of the air are _______ and _______
Convergence and divergence
89
The three major forces that lift air (discounting Gust) are:
Orographic lifting, convention (heating from the surface) , frontal lifting
90
The lifting force that occurs because of displacement is
Frontal lifting
91
When Wind blows along the surface and becomes turbulent, that kind of turbulence is called
Mechanical turbulence
92
A mountain wave is an example of _______wind motion
Gravity wave
93
Stability primarily refers to what condition of an air mass
Constant temperature
94
Under what circumstance with someone describe the air as stable
No vertical movement
95
Air buoyancy refers to what air movement
Vertical
96
Archimedes principle is helpful in understanding air movement because
Heavier air displaces lighter air
97
What is the gas law
Pressure divided by density (temp) = ratio
98
How many adiabatic lapse rates are there-what are they called?
A. standard adiabatic lapse rate = 2°C per thousand feet
B. dry adiabatic lapse rate = 3° per thousand feet
C. Wet adiabatic lapse rate = 1° per thousand feet
99
As altitude increases, pressures changes how?
Decreases
100
During temperature changes, Expansion does what to____ Air and compression does what to______air
Cools and heats
101
Adiabatic cooling will always accompany______ Motion and adiabatic heating Will always accompany_______motion
Upward and downward
102
Atmospheric sounding is the process of measuring what?
Measuring the atmosphere
103
Unsaturated Air will flow upslope at a rate of ___per thousand feet
3°
104
The tropospheric(ISA) lapse rate(LR) is ____Per thousand feet
2°
105
The DALR is ____Per thousand feet
3°
106
The following formula represents what kind of atmospheric stability?
LR > DALR
Unstable
107
The following formula represent what kind of atmospheric stability?
LR
Stable
108
The following formula represent what kind of atmospheric stability?
LR = DALR
Neutral
109
What is the condition where warm air is above cold air?
Temperature inversion
110
In the lower stratosphere, what is the ISA lapse rate?
0°
111
What formula describes "superadiabatic" instability or an unstable air mass?
LR >DALR
112
What kind of air mass will have smoother air?
Stable
113
What kind of air mass will have bumpy air ?
Unstable
114
Which kind of clouds will be likely to occur and stable air?
Stratiform
115
Which kind of clouds will be likely to occur in unstable air?
Cumulus
116
Which conditions will be most likely to create low altitude temperature inversions?
Clear cool nights with Calm light winds (stable air)
117
How does heating from below affect air stability?
Decreases stability
118
Why are high pressure areas more stable than low-pressure areas?
High-pressure air sinks and become stable while low-pressure air rises and becomes unstable
119
If your reading a meter and it states that rain ended at what time did the metal come out ?
It was prior to when the metar came out
