Met General Flashcards

1
Q

What part of the atmosphere contains all the elements of weather?

A

The Troposphere

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2
Q

What are the layers of our atmosphere?

A
  • Troposphere
  • Stratusphere
  • Mesosphere
  • Thermosphere
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3
Q

Colourless gass that absorbs ultraviolet radiation and is found at all altitudes?

A

Ozone

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4
Q

The earth’s surface is heated by?

A

Short wave solar radiation

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5
Q

Temps in the lower stratosphere approximate those of the ___.

A

Tropopause

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6
Q

Whenever air moves horizontally, it is influenced by the Coriolis force, which is caused by ___.

A

Rotation of the earth.

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7
Q

Atmospheric motions in the vertical direction?

A

Convection

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8
Q

Heat transfer from molecule to molecule without significant movement of the molecules?

A

Conduction

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9
Q

When surface temps rise due to daytime heating, this heating effect is transmitted aloft by…

A

Convection

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10
Q

What area experiences the least diurnal (day/night) range in temperature?

A

Termperate zone oceans

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11
Q

Lifting process that causes choppy turbulence below 3000’

A

Mechanical turbulence

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12
Q

List 3 lifting agents?

A
  1. Convection
  2. Convergence
  3. Mechanical Turbulence
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13
Q

Convergence describes air that is…

A

squishing into an area (converging)

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14
Q

What process can result in expansional cooling, condensation and cloud formation?

A

Overrunning

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15
Q

Characteristics of a Cyclone?

A
  • low pressure
  • left rotation (anti-clockwise)
  • ascending air
  • convergence (inward spiraling winds)
  • warm air
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16
Q

Characteristics of an Anticyclone

A
  • high pressure
  • right rotation (clockwise)
  • descending air
  • good weather
  • cold air
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17
Q

The term used when no heat is transferred. This could be used for a rising parcel of air that does not transfer any heat in or out as it ascends.

A

Adiabatic

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18
Q

Subsiding air warms at the ___ lapse rate?

A

dry adiabatic lapse rate

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19
Q

Air descending down the lee side of mountain slopes will warm at the ______ rate.

A

dry adiabatic lapse rate

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20
Q

When air subsides, the relative humidity ___

A

decreases.

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21
Q

What happens during the condensation process?

A

Latent heat is released to the surrounding air.

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22
Q

Dry adiabatic lapse rate

A

3°C / 1000’

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23
Q

Why does saturated air that’s rising cool less rapidly than if it were dry air?

A

Because heat is released during the condensation of water vapor.

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24
Q

What are the Dry, Saturdated and Environmental lapse rates?

A
  • DALR - 3°/1000’
  • SALR - 1.5°/1000’
  • ELR - 1.98°/1000’
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25
Q

What lapse rate should you use when calculating cloud bases?

A

2.5°/1000’

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26
Q

The stability and instability of the atmosphere refers to the suppression or promotion of ____ movement.

A

vertical

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27
Q

The stability of warm, dry air depends on the relationship between…

A

the dry adiabatic lapse rate and the environmental lapse rate.

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28
Q

Stable air is associated with what type of visibility?

A

sustained low vis

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29
Q

Haze layers, drizzle and fog are features of what type of air?

A

Stable air

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30
Q

One weather condition that may affect visibility in unstable air is…

A

Snow showers

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31
Q

Stable air becomes unstable as a result of…

A

Heating from below

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32
Q

What are altocumulus castellanus?

A

Mid-level tower clouds.

Castellanus clouds are evidence of mid-atmospheric instability.

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33
Q

What process inhibits or blocks rising air?

A

An inversion

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34
Q

The vertical distance between two specific pressure levels is ___ in cold air than in warm air.

A

less

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35
Q

A trough is…

A

An elongated area of relatively low pressure.

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36
Q

A neutral area, not bonded by any one isobar, within which light winds are blowing and the weather is changing very slowly, exists between two high and two low pressure systems. The name given to this indefinite pressure area is…

A

A col

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37
Q

Port (left) drift = aircraft true altitude ____

A

incresing

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38
Q

Starboard (right) drift = aircraft true altitude ___

A

decreasing

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39
Q

What two factors are used to calculate density altitude?

A

The airport’s pressure altitude and air temp.

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40
Q

True altitude is greater than indicated in conditions of…

A

warm air and high pressure.

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41
Q

What is MSL pressure?

A

Station pressure reduced to MSL using the average surface temp for the last 12hrs.

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42
Q

What is altimeter setting?

A

Station pressure reduced to MSL assuming ISA conditions.

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43
Q

Terrain clearance must be monitored closely when pressures are ___ and temparatures are ___.

A

low, low

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44
Q

The relationship betwene the amound of water vapor in the air and the maximum possible vapor that could be held by the air at th that temp and pressure.

A

Relative humidity

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45
Q

What does relative humidity depend on?

A

Absolute humidity and temperature.

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46
Q

What will the temperatures be if measuring air with a 100% humidity using a dry bulb and a wet bulb thermometer?

A

The same temp if the relative humidity is 100%

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47
Q

An instrument that is used to measure air humidity?

A

Psychrometer

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48
Q

The height of the cloud base is most depended on?

A

The moisture content of the air.

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49
Q

Clouds and precip are most common in areas of ____ air?

A

Ascending

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50
Q

What type of cloud frequently forms as a result of evaporation from rain, rather than expansion cooling?

A

Stratus.

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51
Q

Wisps or streaks of water or ice particles that fall from the bottom of a cumuliform cloud and evaporate or sublimate before reaching the ground appear as?

A

virga

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52
Q

How does drizzle form?

A

by the coalescence of stratus cloud droplets.

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53
Q

Snow falling from a layer of stratocumulus cloud would indicate that?

A

The liquid water content in the cloud is decreasing.

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54
Q

An airport weather observer reports snow grains; this type of precip would imply?

A

that freezing drizzle is present aloft.

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55
Q

A large area of land or ocean of relatively uniform characteristics and above which an air mass can form is known as a…

A

source region

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56
Q

How are air masses classified?

A

According to their moisture content

57
Q

What weather would you expect when Continental Arctic (cA) air moves south over the Great Lakes during the winter?

A

snow showers just south of the south shoreline.

58
Q

Review the air masses.

A
59
Q

Maritime Polar (mP)

A

cool, moist

60
Q

Continental Arctic (cA)

A

very cold, dry

61
Q

Continental Polar (cP)

A

cold, dry

62
Q

Continental Tropical (cT)

A

hot, dry

63
Q

Maritime Tropical (mT)

A

warm, moist

64
Q

What weather would you expect when Maritime Tropical (mT) air moves north over the Great Lakes in the spring and early summer?

A

Low stratus, drizzle and fog over the north shores.

65
Q

What would initially happen when Continental Arctic (cA) air moves southbound over the Great Lakes in the early autumn?

A

Steam fog over the northern portions of the lakes.

66
Q

Fronts are named according to…

A

the direction of movement of the colder air mass

67
Q

Which two weather fronts would most likely be present on Canadian weather charts during the winter?

A

Continental Arctic and Maritime Arctic

68
Q

What is the sequence of clouds you would expect to encounter as you fly in cold air towards an approaching warm front?

A

Cirrus (CI), Cirrostratus (CS), Altostratus (AS), Nimbostratus (NS)

69
Q

The extensive stratiform cloud decks commonly associated with warm fronts are caused by…

A

overrunning warm air that expands and cools.

70
Q

4 factors that determine cold frontal weather.

A
  • the stability of the warm air
  • moisture content of the warm air
  • speed of the font
  • steepness of frontal surface
71
Q

How do the clouds and precip associated with a cold front develop?

A

by warm air lifting on the frontal surface, then expanding and cooling.

72
Q

A cold front with a steep frontal surface that is advancing with great rapidity upon moist, unstable air produces a suitable environment for…

A

a squall line thunderstorm

73
Q

A combo cold / warm front is most likely associated with…

A

a trowal

74
Q

Future movement of the centre of a frontal depression in the Northern Hemisphere tends to be parallel to the…

A

warm sector isobars

75
Q

You fly westbound through a trowel, what happens to the temperature?

A

tremp rises, then falls.

76
Q

At a stationary front, the cold air moves…

A

parallel to the front

77
Q

What’s an occluded front?

A

When a cold front overtakes a warm front. Warm air is separated (occluded) from the center of the low pressure system at the ground.

78
Q

What’s a stationary front?

A

It’s a pair of air masses, neither of which is strong enough to replace the other.

79
Q

What’s a col?

A

A col or trough is an elongated region of relatively low pressure

80
Q

A condition favorable for the development of strong katabatic winds is…

A

a glacier region

81
Q

What’s a warm katabatic wind called?

A

A chinook

82
Q

What do you call the distance to the farthest point on the ground that can be seen from an aircraft?

A

slant vis

83
Q

What’s steam fog?

A

fog which is formed when very cold air moves over warmer water.

84
Q

What is radiation fog?

A

Fog formed when the land cools after sunset on a calm clear evening. The cool ground produces condensation in the nearby air by heat conduction.

85
Q

What doesn’t radiation fog form over the ocean?

A

because the ocean doesn’t cool by radiation at night

86
Q

Does industrial smoke aid in the development of radiation fog?

A

Yes

87
Q

Advection fog forms over both ___ and ___ while radiation fog forms only over ___.

A

land, water, land

88
Q

What type of fog is caused by adiabatic cooling?

A

upslope fog

89
Q

What happens to moist air moving west across the Prairies?

A

creates widespread upslope fog as it approaches the Rocky Mountains.

90
Q

Ice fog forms by ___

A

sublimation

91
Q

Large supercooled water droplets are most likely found in the ___ levels of cloud formed in ___ air where temps are ___

A

lower, unstable, just below freezing.

92
Q

How is Rime ice formed?

A
  • When small supercooled water droplets freeze on contact with a surface which is below zero.
  • low catch rate, small droplets
  • droplets freeze immediately without spreading
93
Q

How is clear ice formed?

A
  • forms when temperatures are around 2C to -10C
  • large water droplets that spread and freeze
  • freezing drizzle or freezing rain.
94
Q

A cloud formed in stable air will have ___ supercooled water with height when temperatures are ___ freezing

A

more, just below

95
Q

Icing in freezing drizzle is the worst at the ___ of the cloud.

A

bottom

96
Q

Flying through what type of weather can cause rime ice?

A

freezing fog

97
Q

Supercooled rain that freezes while falling through a sub-freezing layer becomes…

A

ice pellets

98
Q

When the dewpoint temp is below -0.5°C, it’s sometimes referred to as?

A

frost point

99
Q

The term used to describe the growth of a descending ice particle as it collides with nearby water droplets which then freeze onto the particle

A

Riming

100
Q

What is hoar frost?

A
  • Occurs when a sub-zero surface comes into contact with moist air.
  • Water vapour turns directly into ice by sublimation
101
Q

Besides a lifting force or triggering action, what other two conditions are necessary for the formation of a thunderstorm?

A
  • lots of moisture
  • a steep lapse rate
102
Q

What indicates the arrival of the mature stage of a thunderstorm?

A

precip at the surface

103
Q

What indicates the dissipating stage of a storm cell?

A

downdrafts through the majority of the cell

104
Q

At what stage of development of a thunderstorm cell would the most serious icing problem be present?

A

just before the mature stage

105
Q

Lightning strikes are at the highest probability at altitudes where the temperature is between…

A

-5°C and +5°C

106
Q

Mammatus clouds are associated with…

A

violent thunderstorms and tornadoes

107
Q

The name given to a low-level, tube-shaped, detached cloud seen at the leading edge of a cumulonimbus, which is part of a line of thunderstorms?

A

Roll cloud

108
Q

Mesocyclonic movement detected by high-resolution Doppler radars is a sign of…

A

tornado development

109
Q

What’s the recommend procedure if you accidently enter a thunderstorm?

A
  • slow down to Va
  • don’t try to maintain a specific alt or speed.
  • maintain present heading
110
Q

The shaft of a microburst at the surface is normally about ___ wide

A

2.2nm or less

111
Q

A condition associated with potentially dangerous wind shear, especially during takeoff and landing is…

A
  • a low level temperature inversion
  • with strong winds above the inversion
112
Q

These are 3 characteristics of ____.

  1. occur mostly in summer
  2. form over flat terrain during the presence of southwest winds
  3. usually associated with temperature inversions
A

Nocturnal Jet Streams

113
Q

Before takeoff, you notice rain falling from a convective cloud with a base of around 15,000’ and the rain is evaporating before it reaches the ground. This could signal the presence of…

A

a dry microburst

114
Q

These are 3 characteristics of ___.

  1. the presence of virga
  2. linked to cumulus clouds with a high base
  3. evaporative cooling
A

a dry microburst

115
Q

Downdrafts associated with a microburst can be as strong as…

A

6000 feet/min

116
Q

What types of winds can cause intense wind shear at arctic airports or at airports close to mountains?

A

valley, katabatic or funnel winds

117
Q

Altocumulus standing lenticular clouds are a sign of…

A

a mountain wave

118
Q

The lowest group of stationary clouds associated with a mountain wave is…

A

a rotor cloud

119
Q

Where is the most powerful rotor cloud located when it’s associated with the presence of a mountain wave?

A

under the first wave crest

120
Q

The part of the mountain wave system that usually presents the most severe turbulence is located…

A

between the ground and the top of the rotor cloud

121
Q

A high-level jet stream oriented perpendicular to the axis of the mountain range can mean what danger?

A

severe turbulence at high altitude associated with the mountain wave system.

122
Q

How can a mountain wave affect the altimeter?

A

It can falsely read high when flying through the crest of a mountain.

123
Q

On a constant pressure, upper air chart the altitude gradient can be considered as the ___ of the pressure surface.

A

slope

124
Q

On upper air contour charts, the wind blows ___ the contours in the same way that the 2000ft wind blows ___

A

along, along the surface isobars

125
Q

Upper Air Contour Charts

A
  • wind blows parallel to the height contours
  • if the height contours are curved then centrifugal force acts on the wind
  • the closer the contours, the stronger the wind
126
Q

If the ___kt isotachs are spaced closer together than ___nm on the 250 hPa upper-air chart, you can expect sufficient horizontal shear from the occurrence of clear air fight.

A

30kt, 90nm

isotach = a line on a map connecting points of equal wind speed.

127
Q

The tropopause can be identified during a climb in the upper troposphere by the occurrence of…

A

an abrupt change in the temp and lapse rate.

128
Q

There is an abrupt change in the height of the tropopause over each…

A

frontal surface

129
Q

Over a warm air mass the Tropopause is ___ and ___

A

higher and colder

130
Q

In ISA conditions the height and temp of the tropopause is…

A

36,090 ft and -56.5°C

131
Q

Steep pressure gradients and ___ constitute a major factor in the formation of jet streams.

A

the Coriolis force

132
Q

Jetstreams usually occur in an area of intensified temperature gradients that normally exist across upper fronts and with their jet cores positioned just under the warm air tropopause, adjacent to the tropopause break.

A
133
Q

North to South jet streams occur when the air beneath the jet stream is colder to the ___ than to the ___.

A

east, west

134
Q

List 3 factors of clear air turbulence (CAT) in relation to jet streams.

A
  • curving jet streams are more likely to have turbulent edges especially when they curve around a deep pressure trough
  • Wind shear and CAT adjacent to jet streams are more intense above and to the lee side of mountain ranges.
  • when two jet streams merge it can produce CAT
135
Q

Turbulence associated with upper-level troughs is usually more ___ than with ridges.

A

severe

136
Q

The jet stream core has the worst vertical extent of clear air turbulence on the side with ___ pressure and the ___ temperature air mass.

A

low, cold

137
Q

If you’re flying across the jet stream in North America and experience clear air turbulence and notice the OAT is increasing, you should ___

A

climb

138
Q

The polar jet stream moves ___ in the winter, has ___ core speeds and stays at a ___ lower altitude.

A

south, slower, lower

139
Q

Flying near the jet stream with a crosswind, you encounter moderate clear air turbulence and notice the OAT is constant. You should…

A

climb or descend