Weather Flashcards
(187 cards)
1
Q
What is the atmosphere
A
The envelop of air that surround earth
2
Q
By weight, how much of the atmosphere is located below 18,000?
A
1/2
3
Q
What is the movement of air around the surface called
A
atmospheric circulation
4
Q
What gas accounts for 78% of the gas in our atmosphere?
A
Nitrogen
5
Q
What affects pressure changes
A
Altitude, temperature, density of air.
6
Q
Pressure charts use what pressure indication?
A
milibars
7
Q
what is the acronym for milibars
A
(mb)
8
Q
What are local barometric pressure readings converted to?
A
sea level pressure
9
Q
What are isobars
A
pressure area outlines
10
Q
On a pressure chart how far apart are isobars placed
A
4 mb apart, unless significant pressure gradient then 2 mb apart
11
Q
What does rising pressure indicate
A
Approach of fair weather
12
Q
What does falling pressure usually indicate?
A
approaching of bad weather
13
Q
What is temperature
A
Measurement of amount of heat, expresses a degree of molecular activity
14
Q
what is incoming solation heat called
A
insolation
15
Q
what is radiating heat from earths surface called?
A
Terrestrial radiation
16
Q
On the Fahrenheit scale what is freezing
A
32 degrees
17
Q
on the Fahrenheit scale what is boiling
A
212 degrees
18
Q
on the Celsius scale what is freezing
A
0 degrees
19
Q
on the Celsius scale what is boiling
A
100 degrees
20
Q
how do you convert Fahrenheit to Celsius
A
subtract 30 and then divide by 2
21
Q
how do you convert Celsius to Fahrenheit
A
multiply by 2 add 30
22
Q
what causes atmospheric circulation
A
temperature variations
23
Q
What is Diurnal Variation
A
Change of temperature from day to night
24
Q
when does terrestrial radiation cease?
A
After sunrise when insolation overtakes terrestrial radiation
25
Does water absorb or radiate heat quickly or slowly
quickly
26
where does abrupt temperature changes occur?
along water shorelines
27
where prevailing winds come from a large body of water what happens to temperature changes
slow temperature changes with small gradient
28
where prevailing winds come from dry barren areas what happens to temperature changes
quick temperature changes with large gradient
29
What happens to temperature with increasing altitude?
Temperature typically decreases
30
What is a lapse rate
the decrease of temperature with increase of altitude
31
What is an inversion
a layer of warmer air over a layer of colder air
32
What is conduction
the transfer of heat energy from one substance to another
33
what is convection
The transfer of heat in a fluid
34
where does conduction occur
a few centimeters off of the surface
35
when does convection ocur
as the ground is heated by the sun.
36
When do inversions develop
cool clear nights with light and variable winds
37
Why do inversions occur
Grounds air cools faster than moist air above
38
Whey do low level inversions dissipate
as air is heated with insolation the inverted air begins to mix due to convections
39
List 3 ways heat is transferred to the atmosphere
Radiation, Conduction, convection
40
What is radiation
transfer of heat by electromagnetic waves
41
Is there a medium needed for heat transfer in radiation
no
42
What are principle reflectors in meterology
water vapor, particulate matter and the earths surface
43
what is advenction
the horizontal transfer of heat, usually by wind
44
what is the adiabatic process
change of temperature without the transfer of heat
45
in the adiabiatic process what results in warming
compression
46
in the adiabiatic process what results in cooling
expansion
47
What happens to air as it rises
pressure decreases, volume increases, temperature decreases
48
what happens to air as it descends
pressure increases, volume decreases and temperature increases
49
what are the basic characteristics of any air mass
temperature and humidity
50
what is the primary factor in determining air mass characteristics
terrain
51
what is an air mass
a large body of air that has uniform characteristics
52
What are characteristics of an air mass
Stability, cloud type, sky coverage, visibility precipitation, icing, turbulence
53
how are air masses grouped
by region of origination
54
what types of airmasses are there
polar or tropical and maritime or continental
55
what happens to air masses as they move over a warm surface
the air is heated from below and becomes unstable
56
what happens to air masses as they pass over a cold surface
air is cooled from below creating a stable air mass with poor visibility
57
why is poor visibility a characteristic of stable air
Particles are trapped and cant rise
58
what local weather can be found with cold, stable air
low stratus clouds and fog
59
what does moist unstable air cause
Cumulus clouds, good visibility , localized showers and turbulence
60
The heating and cooling of air can cause what in density
it can cause density variations
61
what happens to a barometer in a low pressure
pressure decreases towards the center
62
which way does the wind spin in a low
counter clockwise
63
What are the flying conditions noted with a low pressure system
poor flying conditions, low clouds, restricted visibility (fog and precipitation) strong gusty winds, turbulences
64
what happens to air if it passes over a colder surface
creates a stable air mass with poor visibiltiy
65
Why is poor visibility a characteristic of stable air
particles are trapped and cant rise
66
what local weather can be found with cold stable air
low stratus clouds and fog
67
What happens to air as it is heated from below
it becomes unstable
68
what can unstable air cause
cumulus clouds, good visibility localized showers and turbulence
69
What are flying conditions of a low
low clouds, restricted visibility (fog and precipitation) strong gusty winds, turbulences
70
what is the general airflow of a low pressure?
towards the center and up
71
what is a high pressure system
barometric pressure increases towards the center
72
heating and cooling of the air can do what to density
it can cause density variations
73
what happens to pressure in a low
barometric pressure decreases towards the centre
74
which way does the wind spin in a low
counterclockwise
75
what is advection
the horizontal transfer of heat
76
what is the adiabatic process
the change of temperature without the thansfer of heat
77
In the adiabiatic process what results in warming
compression
78
in the adiabiatic process what results in cooling
expansion
79
what is conductions
transfer of heat energy from one substance to another
80
where does conduction occur
a few centimeters off the surface
81
what is convection
the transfer of heat in a fluid
82
when does convection occur
when the ground is heated by the sun (insolation)
83
what is raiation
the transfer of heat by electromagnetic waves
84
is there a medium needed for heat transfer in radiation
no
85
what are principle reflectors in meterology
water vapor, particulates, earths surface
86
where do abrupt temperature changes occur
along water shorelines
87
what is the general pattern of air flow in a high pressure system
clockwise
88
what are flying conditions of a high pressure system
few clouds, light and calm winds less turbulence
89
what type of front moves most rapidly
cold fronts
90
how fast do cold fronts move
about 25-30 miles per hour
91
what weather pattern could you see with a cold front
rain showers, haze, wind from the S.W. high dew point and falling barometric pressure
92
how is visibility in a cold front
poor
93
what types of clouds are present in a cold front
cirriform, cumulus and cumulonimbus
94
what winds can be seen in a cold front
light and variable
95
when is the movement of pressure systems more rapid?
winter
96
what is a front
it is the boundary between two masses
97
how are fronts classified
which type of air mass is replacing another
98
what are fronts boundaries for
two air masses with different densities
99
what is primary control in air density
temperature
100
what types of fronts are there
Cold, Warm Stationary and occulded
101
how are fronts determined
movement of air masses involved
102
what is a cold front
advancing edge of a cold air mass
103
when does a cold front occur
a mass of cold dense air replaces a body of warmer air
104
what is a warm front
trailing edge of a cold air mass
105
how fast to warm fronts move
10-15 mph
106
what causes the wind to move
the corilois force, pressure gradient and surface friction
107
what is atmospheric circulation
movement of air around the surface of the earth caused by uneven heating
108
in general atmospheric theory states ow pressure exists over what region
equatorial
109
In general atmospheric pressure theory states high pressure exists over what region
polar regions
110
where is the greatest amount of air deflection noted
around the poles
111
Coriolis force deflection is perpendicular to what
airflow
112
which direction in Northern Hemisphere does air get deflected
to the right
113
what are pressure gradients
difference in pressure between high and low
114
wind speed is directly proportional to
pressure gradient
115
what are the three components that affect wind
Coriolis, pressure gradients, surface friction
116
what is the humidity like in a high pressure system
dry
117
is the air in a high pressure system stable or unstable
stable
118
does the air descend or ascend in a high pressure
descend
119
Is air in a low stable or unstable
unstable
120
what weather is associated with a low
increase in cloudiness and precipitaitaion
121
what is anabatic wind
winds that blow up a steep mountain side
122
when do anabatic winds occur
day time, calm sunny weather
123
what is a katabatic wind
winds flowing down slope
124
when do katabatic winds occur
at night
125
how are cloud types determined
height, shape and behavior
126
how are clouds classified
height at bases
127
what are the 4 major cloud types
low, middle, high, and clouds with vertical development
128
what are specific cloud types
cumulous, stratus, cirrus, castellans, lenticularis, nimbus, fracto and alto
129
what are outward appearance of cumulous clouds
heaped towering clouds, piles
130
what are the outward appearance of stratus clouds
formed in layers
131
what are the outward appearance of cirrus clouds
ringlets, fibrous clouds at high level
132
what are the outward appearance of Casellanus clouds
common base with separate vertical development
133
What are the outward appearances of lenticular clouds
lens shaped over mountains, indicate strong winds
134
What are nimbus clouds
rain bearing clouds
135
what are fracto clouds
ragged or broken
136
what are alto clouds
high elevation clouds
137
where do low level clouds form
near earths surface
138
what cloud groups make up low level clounds
stratus and stratcumulous
139
Where do strato clouds form
near the surface
140
what flying conditions do strato clouds form
poor visibility flying conditions
141
where can mid level clouds form
6500 to 20k agl
142
What cloud groups make up mid level clouds
Altocumulus, alto stratus, nimbostratus
143
what are high clouds
clouds that form above 20k feet AGL
144
where do high clouds form
above 20k in stable air
145
what are high cloud groups
cirrus, cirruscumulus, cirrostratus
146
what are cumulous clouds known for
extensive vertical development
147
what do clouds with extensive vertical development develop into
thunderstorms
148
what do towering cumulous clouds indicate
instability and turbulance
149
flight in cumuliform can be
turbulent in and around cloud masses
150
flight in stratoform clouds can be
smooth
151
nimbus means
rain or precipitation producing clouds
152
what is dew point
point where air can hold no more moisture
153
at what rate does unsaturated air cool?
5.4 degrees f per 1,000
154
what happens to dew point as altitude increases
dew point decreases 1 degree f per 1,000 feet
155
what is convergence of temp and dew point
4.4 degrees
156
What is the formula for determining cloud bases
temperature-dew point = temperature dew point spread, temperature dew point spread is divided by convergence rate multiplied by base of clouds gives elevation AGL
Temp-D.P=TDS
TDS/CR*1000=base of clouds
157
what is fog
clouds that begin within 50 feet of surface
158
what are natural conditions for fog to occur
relative high humiditiy
159
what wind condition is favorable for fog
light wind causing mixing of cooled air
160
What is radiation fog
when heat in the air is given back to atmosphere causing cooling and ambient air reaching dew point
161
when is radiation fog most likely
Clear Skies, High moisture content, and wind less than 7 knots
162
What does an unstable air mass allow
upward and downward movement of air
163
what happens to rising air
expands and cools
164
what does moisture do to air densitiy
decreases air density
165
what air mass is more stable moist or dry
Dry air masses are more stable
166
Cool Dry air is very
stable
167
Cool Dry air resists
vertical movement
168
what type of air mass does the greatest instability occur
moist warm air.
169
what does air stability depend on?
vertical distribution of airs weight
170
what are types of air stability
```
Absolute stability
Absolute instability
conditional stability
neutral stability
convective stability
```
171
when does absolute stability occur
when actual lapse rate is less than adiabatic lapse rates
172
when does absolute instability occur
when the actual lapse rate is greater than the dry adiabatic process
173
list the 4 categories of turbulance
thermal
mechanical
frontal
wind shear
174
what is a thermal
updraft in a small scale convective current
175
what is Mechanical turbulance
when air flows over irregular surfaces
176
What does Mechanical turbulence depend on
speed of wind,
nature of obstruction
stability of air
angle at which air moves over obstacle
177
what is frontal turbulance
lifting of warm air by frontal surface
178
what is the most severe frontal turbulence associated with
Fast moving cold fronts
179
What is a wind Shear
a steep grade of wind velocity
180
what are low level wind shears associated with
passing frontal storms, thunderstorms and temperature inversions
181
how many convective cells does a mature thunderstorm have
one or more
182
How many stages are in a thunderstorm
3 stages
183
What are the three stages of a thunderstorm
Cumulous, Mature, dissipating
184
what is the chief distinguishing feature of the cumulous stage
up drafts
185
What initiates the mature stage of a thunderstorm
surface rain, and adjacent updrafts and down drafts
186
what happens to pressure in a thunderstorm
abrupt fall in pressure as storm approaches
| abrupt rise in pressure as with rain as storm moves on
187
what are frontal thunderstorms caused by
lifting of warm moist conditionally unstable air
