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UH 72 > EXAM ( Weather ) > Flashcards

EXAM ( Weather ) Flashcards

1
Q

clouds

What are the 3 cooling process

A

Adiabatic
Cooling due to change in pressure - expansion of air
Nocturnal (stratus)
“night sky cooling”
Heat radiates away from an object/surface to the nightsky
Advection
Caused by warm air passing over cold surface

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2
Q

What are the 4 low clouds ?

A

Cumulus (CU)
Unstable - no rain
Stratus (ST)
Stable - no rain
Stratocumulus (SC)
Inbetween (stabile/unstabile)
Cumulusnimbus (CB)
Unstable - Rain

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3
Q

Is vertical clouds stable or unstable ?

A

unstable

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4
Q

What does stability in clouds mean ?

Look up

A

How likely they are to lift vertical and have percipitation.
(Unstable = Lift vertical and can hold rain)

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5
Q

What are the middle clouds ?
Name + Abbreviation + characteristics

A

Altostratus (AS)
Stable no rain
Altocumulus (AC)
unstable no rain
Nimbusstratus (NS)
Stable + rain

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6
Q

What are the high clouds ?
Name + Abbreviation + characteristics

A

Cirrus (CI)
No stability linked - no rain
Cirrostratus (CS)
Stable (stratus) - no rain
Cirrobumulus (CC)
Unstable (cumulus) - no rain

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7
Q

What’s natural air ?

A

Dry air + Condensation nuclei + Water vapor

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8
Q

What’s the composition of the atmosphere ?

A

78% Nitrogen
21% Oxygen
1% Argon and other

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9
Q

What’s the 5 atmospheric layers?

A

Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

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10
Q

What is atmospheric circulation (Three cell theory) caused by ?

A

1 Uneven heating
2 Tilt of the earth
3 Coriolis force

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11
Q

atmospheric circulation

Where is the wind coming from (what are they called) ? :
1 0-30º lattitude
2 30-60º lattitude
3 60-90º lattitude

A

1 NE trade winds
2 Westerlies
3 Polar easterlies

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12
Q

4 Changes that have to be seen for a front to be in place

A
  1. Temperature change
  2. Dew point number change -
    Increase warmfront - drop coldfront
    (moister content of airmass is DP)
  3. Pressure fall then rise
    (Decreasing as low pressure comes in - as front moves away then high pressure behind increases pressure)
  4. Wind shift

3) all fronts are low pressure

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13
Q

What are the 6 air mass “codes” ?

A

C = Continental (dry air)
M = Maritime (moist air)
A = Arctic (70-90º - cold)
P = Polar (40-60º - cold)
T = Tropical (10-30º - warm)
E = Equatorial (0-10º - warm)

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14
Q

What are the 4 types of heat transfer ?

briefly describe

A

Radiation (electromagnetic waves)
Conduction (Touch)
Convection (movement of partical transporting heat from warm to cold - Vertical)
Advection (horizontal moving air)

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15
Q

What is the “OLR”

A

Observed lapse rate
A change in temperature with altitude
2º per 1000’

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16
Q

Is seabreez an exampel of convection og advection - why ?

A

Advection because air is being “sucked” horizontally from the sea into land where air is being warmed and lifted - therefore creating a void to be filled.

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17
Q

What’s a temperature inversion ?

A

An altitude where this is warmer air above colder air temperature is increasing with altitude

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18
Q

What are the two types of temperature inversions ?

A

1 Radiation - nocturnal
(ground releases heat at night and air above is warmer than at the surface)
2 Frontal
(When a cold airmass undercuts a warm airmass - cold airmass can push beneath because it’s more dense)

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19
Q

What can prevent a radiation temperature inversion ?

A

Cloud layer (OVC) above the ground deflects the heat back down again

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20
Q

Simply put - What’s the difference between convection & advection ?

A

Convection is vertical
Advection is horizontal

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21
Q

What causes wind speeds ?

A

PGF Pressure gradient force

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22
Q

Would you expect the wind to be strongest at point A or B ?

A

B - Due to the isobars laying closer together

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23
Q

If you have a left crosswind pushing you to the left - are you moving towards or away from low pressure ?

A

Moving towards low pressure

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24
Q

If you go from KOZR with an altimeter setting of 30.22 to KMAI 30.01 - and you don’t correct you kollsman window - what is your true altitude in regard to you indicated ?

A

“From high to low - look out below” = your true altitude is lower than your indicated

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25
Q

How does moister in the air affect flight performance?

A

Moister = less air density = higher density altitude = reduction in lift and engine performance

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26
Q

Name the 3 atmospheric conditions which provide the best lift

A

1) High pressure
2) Low humidity
3) Low temperature

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27
Q

What type of clouds would you expect at low altitude in an unstable enviroment ?

A

Cumuliform clouds

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28
Q

What type of clouds would you expect at low altitude in an stable enviroment ?

A

Statiform clouds

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29
Q

All fronts are _____

A

Low pressure

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30
Q

____ are lines of equal pressure, seperated by ____ mb. Above ____ the wind blows ____ to the ____

A

Isobars are lines of equal pressure, seperated by 4 mb. Above 2000’ the wind blows parallel to the isobars

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31
Q

What’s the standard atmospheric pressure - Hg & hP/mb

A

29.92 Hg
1013.2 hP/mb

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32
Q

What’s the characteristics of a High pressure system/weather?

A

Sinking air near center
Clockwise wind direction
Divergence (air moves away)
Good visibility
Good flying conditions

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33
Q

What’s the characteristics of a Low pressure system/weather?

A

Lifting air near center
Counterclockwise wind direction
Convergence (air moving towards)
Limited visibility due to clouds/fog/rain
Poor flying conditions

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34
Q

What information can be deduced from the isobars ?

A
  • High / low pressure
  • Wind direction
  • Relative wind speeds
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35
Q

What’s the definition of the pressure gradient force ?

A

Rate at which air will accelerate depends on rate at which pressure changes with distance

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36
Q

Which force causes the wind to blow ?

A

Uneven heating og earths surface creating a Pressure gradient force

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37
Q

How does coriolis force affect circuling air in the northern hemisphere ?

A

Deflection to the right (from the direction of movement)

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38
Q

Which two forces affect global wind direction ?

A

Pressure gradient force and coriolis

(uneven heating is the reason the winds occur)

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39
Q

How does the wind flow in relation to the isobars below 2000’

A

Across the isobars

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40
Q

Buys ballot’s law

Standing with your back to the wind - the low pressure will be to your? (left/right)

A

Left

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41
Q

When you’re moving towards a low pressure - what weather conditions should you expect ?

A

Lifting air, vertical clouds, turbulence and possible storms

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42
Q

Explain which states (from/to) each refer to:
Sublimation
Deposition
Evaporation
Condensation

A

Sublimation
Solid to gas
Deposition
Gas to solidt
Evaporation
Liquid to gas
Condensation
Gas to liquid

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43
Q

When somthing is “saturated” what does that mean ?

A

It’s holding as much water/moister as possible

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44
Q

What’s “dew point” ?

A

A temperature at which the air is saturated - beyond this visible moister and rain will form.

2 degrees before dew point = visible moister possible

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45
Q

What’s relative humidity ?

A

A procentage of how humidt the air is in regard to how much water is can hold.

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46
Q

What’s an adiabatic process ?

A

A change in temperature without heat transfer.
Energy transfered due to work (compression of gas or expansion)

Air pushed up the mountain - expands and cools ?

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47
Q

What happens at LCL ?

what’s saturation in % ?

A

Clouds start to form

100% saturation / relative humidity

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48
Q

What’s a front ?

A

A boundary between air masses of different density

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49
Q

Frontal weather is caused by the lifting of ____ and ____ air by ____ and more ____ air

A

Frontal weather is caused by the lifting of warm and moist air by colder and more dense air

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50
Q

Does all fronts have temperature inversions ?

A

YES

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51
Q

What 4 things would you expect a change in during a frontal passage ?

A

1 Temperature
2 Dew point
3 Pressure “fall then rise”
4 Wind shift (approx. 90º)

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52
Q

What happens when warm air is lifted over cold air ?

A

The warm air cools with altitude, condenses and creates clouds

“Make weather”

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53
Q

Cold front

Clouds assosiated ?

A

Cumuliform

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54
Q

What’s a squall line ?

and which front is it assosiated with ?

A

A line of thunderstorms

cold fronts

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55
Q

When the altimeter setting is decreasing and then starts to increase - which front has passed ?

A

a cold front

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56
Q

Cold front

Which direction does the wind blow from behind and infront of the front ?

A

Behind: NW
Infront: SE

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57
Q

What happens to temperature when the cold front has passed ?

A

It’s lower - colder air

58
Q

How does a faster cold front affect weather

A

It becomes more severe - squall lines could form

59
Q

What’s the sequence of clouds during a warmfront

(from front being far away to close)

A

CI - CS - AS - NS

60
Q

Which type of front is mostly stable/unstable air?

A

Coldfront: unstable air
Warmfront: stable air

61
Q

What’s the relation between air temperature and moister ?

A

Colder air masses are dryer - warm air masses holds more water

62
Q

Wind direction behind and infront of a warm front ?

A

Behind: SW
infront: SE

63
Q

What characterises a stationary front ?

A

Clouds and rain for a long time
no movement and upredictable

64
Q

Cold front occlusion definition

A

Cold air overtaking the warm front is colder than the air ahead of the warm front

65
Q

warm front occlusion

A

In a warm occlusion, the cool air mass overtaking the warm front is warmer than the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air.

66
Q

Why is an occluded front considered more complex than the others ?

A

Because it’s a combination of both frontal weathers

67
Q

What the most important element of weather usually not found above the troposphere ?

A

Moister

68
Q

What’s the standard temperature lapse rate?

A

2º per 1000’

69
Q

Cold dense air, lifting warmer less dense air is an example of what type of temperature inversion ?

A

Frontal

70
Q

During low pressure the rising air is ____ ? ( warmed/cooled)

A

cooled

71
Q

What’s the characteristic of air around a high/low pressure below 2000’ ?

A

Low pressure - Converge towards
High pressure - Diverge away

72
Q

What causes winds to flow across the isobars rather than parallel to ?

A

Surface friction

73
Q

A large dewpoint spread indicates (high/low) relative humidity ?

A

low

74
Q

Which clouds are associated with noctural cooling ?

A

Low stratus and fog

75
Q

The frontal inversion of any front always slopes over the ____ and the precipitation associated occurs in the ____ air

A

The frontal inversion of any front always slopes over the cold air and the precipitation associated occurs in the cold air

76
Q

The type of air masses most often associated with fronts in the USA are ____ & _____

air mass abbreviations

A

P & T

77
Q

What’s the definition of a cold front ?

A

The leading edge of an advanding mass of cold air

78
Q

What’s the average speed of a cold front ?

A

25-30 kts

79
Q

In which direction does a cold front generally move ?

A

SE

80
Q

What’s the flight procedure if in the vicinity of a cold front ?

A

Land and wait for weather to pass

81
Q

Define a warm front

A

The trailing edge of a retreating mass of cold air, with warm air moving in behind the frontal symbol

82
Q

Warm fronts generally moves to the ____

A

NE

83
Q

Where does weather occur in regards to a stable warm front ? (Ahead, behind)

A

Ahead

84
Q

What weather hazards could be expected if the warm air being lifted by the warm front is unstable

A

Embedded thunderstorms and/or CB clouds

85
Q

What’s important doing preflight planning when flying in the vicinity of a warm front ?

A

An alternate airport + fuel

86
Q

A stationary front will normally be more similar to that of a ____ but less intense

A

Warm front

87
Q

How does the wind at a stationary front usually flow in relation to the chart symbol ?

A

Parallel to the frontal symbol

88
Q

what’s the definition of fog ?

A

Visible moister with base below 50’ and no visible downward motion

89
Q

What’s the difference between fog (FG) and mist (BR) ?

A

Fog: Visibility less than 5/8 SM
Mist: Visibility greater or equal to 5/8 SM

90
Q

What factors need to be present for fog to occur ?

A
  • Small dew point spread / temperatures
  • Abundant condensaton nuclei
  • Light surface wind (except 2 types)
  • Cooling land surfaces with warm moist air above
91
Q

How does OVC sky affect fog ?

A

Prevents fog og lengthen the time it takes to dissapear

92
Q

Name the types of fog

A

Radiation fog
Advection fog
Precipitation-induced fog
Freezing fog
Upslope fog
Ice fog

93
Q

Explain: Radiation fog

A

Caused by (terrestial) radiation cooling the ground which cools the lower levels of air on clear, calm nights

midnight to sunrise - light winds

94
Q

Explain: Advection fog

A

Caused by surface cooling from warm, moist air flowing over (vertically) a cooler surface

3-9 kts winds

95
Q

Explain: Precipitation-induced fog

Where do we find this type of fog ?

A

Caused by rain falling through a frontal inversion and saturates the cooler air below = visible moister = fog

Ahead of warm front - behind cold front

96
Q

Explain: Upslope fog

A

Caused by moist, stable ar being liftes by sloping terrain

clouds on mountains is also fog - cools adiabatically - wind + 10 kts

97
Q

Explain: Freezing fog

A

Fog which is made of supercool droplets.

If thoses droplets get in touch with an object - they’ll freeze.

Fog in negative temperatures

98
Q

Explain: Ice fog

A

Fog comprised of tiny ice crystals suspended in the air

temps -30 degreese celcius

99
Q

When is frost formed ?

A

Ice crystals formed by deposition of water vapor contacting a cold surface

Cold clear nights

100
Q

When is rime icing formed ?

A

when supercooled water droplets contact a surface

101
Q

When is clear icing formed

A

When large supercooled water droplets contact a surface

During freezing precipitation

102
Q

When does freezing rain form ?

A

When rain droplets fall thru a frontal inversion into a layer of air which has sub zero temperatures

Most common with warm fronts due to shallow slope

103
Q

What’s the categories of icing intensity ?

A

Trace
Only hazardous if encountered + 1 hour
(No matter deicing)
Light
May be hazardous if encountered - 1 hour (Not if deicing)
Moderate
Even short encounters are potentially hazardous
(Deicing necessary)
Severe
Deicing can’t control the hazard - diversion necessary

104
Q

Which 3 factors need to be present for thunderstorms to develope ?

A

1 Unstable or conditionally unstable air
2 High moister content
3 Lifting action

105
Q

Name the 3 types of thunderstorms

A

1 Air mass thunderstorms
(Thermal convective activity)
2 Orographic thunderstorms
(Terrain)
3 Frontal thunderstorms
Types : ( Fast moving cold front creates CB, squall line (CB) created by fast moving cold front, warm front unstable air comes in contact with warmfront slope, Stationary front developed into CBs, Occluded front develope CBs - worst weather, stacked over a spot)

106
Q

What are the 3 stages of a thunderstorm ?

A

1 Towering cumulus
2 Mature
(begins when precipitation starts - vertical currents)
3 Dissipating

107
Q

OWS icing chart

At what altitudes can we expect icing if the following is reported ?

A

Icing from surface to 3000’ MSL

108
Q

What hazards for flight follow icing

A
  • Reduction of lift
  • Increased drag and weight
  • Reduce rotor stall speed
  • Reduce visibility on windshield
  • Block statis/pitot ports = instrument errors
109
Q

OWS turbulence chart

At what altitudes can we expect turbulence if the following is reported ?

A

Surface to 18.000’ MSL

110
Q

When does microburst most commonly occur ?

A

Mid summer in the afternoon when high cloud tops are present

111
Q

What’s the difference between wet and dry microbursts ?

A

Wet has surface rain
Dry has virga
(“dry storm” = rain falls from sky but evaporates before reaching ground)

112
Q

What can stationary fronts develope into ?

A

Frontal waves ( or open waves)

113
Q

What may frontal waves develope into ?

A

An Occluded front

114
Q

If an occluded front symbol is extended from the cold front symbol it is a ____ type occlusion

A

Cold type occlusion

115
Q

What’s procedure when flying in the vicinity of an occluded front ?

A

Circum navigate

116
Q

What are the dissipation factors for most types of fog ?

A
  • Heating
  • Strong winds
  • Greenhouse effect / overcast sky
117
Q

Will an OVC sky slow or speed up the dissipation of fog ?

A

slow

118
Q

What’s the difference between clear ice and rime ice ?

A

The size of the supercooled water droplets

119
Q

Which intensity of icing would require immediate diversion from the affected altitude ?

A

Severe icing

120
Q

Where is freezing rain typically found during winter months ?

A

ahead of a warm front

121
Q

Which OWS chart is the only one that shows numbers in thousands of feet ?
“12” on chart = “12.000”

A

Freezing level chart

122
Q

Is “small temperature/dewpoint spread” one of the factors needed for thunderstorms ?

A

Yes - Because a small dewpoint spread = high moister content - which is one of the three factors in creation of thunderstorms

123
Q

A summertime thunderstorm that occurs every day in the same area is a ____

A

Air mass thunderstorm (Thermal)

124
Q

How do you know a thunderstorm is in the mature stage ?

A

Begins to rain and downdrafts are coming from the cloud

125
Q

What’s the flight procedure when in the vicinity of a thunderstorm caused by thermal activity ?

A

Land og circumnavigate

126
Q

The OWS turbulence chart is drawn for what category of turbulence ?

A

CAT 2

(Out category as Lakota)

127
Q

If an aircraft is rated as CAT 3 for turbulence - will the forecasted turbulence on the OWS chart be experienced less of more ?

A

Less then the severity forecasted

128
Q

What’s the best conditions for a dry microburst to happen

Time a year, Time a day, cloud type

A

Hottest part of the year
Hottest time a day
Convective clouds

Eg. July - 14:00 - CU clouds

129
Q

Who do you contact if your local WX service is closed ?

A

Military operational weather squadron (OWS) - covering your area

130
Q

How does a lower relative humidity affect a/c performance ?

A

Lower RH = Smaller % of moister in air = fewer clouds and better a/c performance

131
Q

How does a lower relative humidity affect a/c performance ?

A

Lower RH = Smaller % of moister in air = fewer clouds and better a/c performance

132
Q

What’s the standard pressure lapse rate with altitude ?

A

1 Hg per 1000’

133
Q

If you don’t reset your altimeter setting - what will you TALT be in regard to your IALT ?

A

Lower

134
Q

Which air mass code and characteristic does each of the 4 airmasses have ?

A
135
Q

What change in wind direction can be expected with a stationary front ?

A

180 degree change

136
Q

Which type of front is the stationary front typically more similar to ?

A

More like the warm front

137
Q

In flight on your instruments - how would can you see that a front as passed ?

A

Change in OAT and windshift

138
Q

If the temperature is decreasing a ____ front has passed

A

Cold

139
Q

If the temperature is increasing a ____ front has passed

A

warm

140
Q

Occlusions happen when the ____ front catches up to the ____ front

A

Cold catches the warm

141
Q

When does frontal waves occur ?

What can it turn into ?

A

When the cold front and warm front shares the same low pressure

Can turn into an occlusion

142
Q

What’s the difference between a cold and warm occlusion ?

A

Cold The cold air overtaking the warm front is the colder than the air ahead of the front and plows underneath both.
Warm The cold air overtaking the warm front is not colder than the. air infront and rides over

UH 72 (42 decks)

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