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CMEL > Weather Information > Flashcards

Weather Information Flashcards

1
Q

Why do surface winds generally flow across the isobars at an angle?

A

surface friction

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2
Q

What are isobars?

A

a line on a weather chart which connects areas of equal or constant barometric pressure

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3
Q

Standard temperature and pressure values for sea level

A

15ºc and 29.92”Hg

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4
Q

What is a Ridge?

A
  • elongated area of relatively high atmospheric pressure
  • air moving out of a high depletes the quantity of air
  • descending air
  • dissipation of cloudiness
  • high pressure
  • good weather
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5
Q

MVFR

A

Marginal Visual Flight Rules

ceiling: 1,000’ - 3,000’
visibility: 3-5 miles

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6
Q

General characteristics of weather near a warm front

A
  • stratiform clouds
  • drizzle
  • low ceilings
  • poor visibility
  • variable winds
  • rise in temperature
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7
Q

The boundary area formed when a warm air mass contacts and flows over a colder air mass

A

warm front

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8
Q

At what rate does atmospheric pressure decrease with an increase in altitude?

A

1”Hg per 1,000’

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9
Q

Define Dew Point

A

the temperature at which a sample of air must be cooled to attain the state of saturation

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10
Q

The density of the air has a direct effect on:

A
  • lift produced by the wings
  • power output of the engine
  • propeller efficiency
  • drag forces
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11
Q

What factors affect air density?

In what way?

A

Altitude - the higher the altitude, less density

Temperature - the warmer the air, less density

Humidity - more humid air, less density

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12
Q

When temperature and dew point are close together (within 5º) what type of weather is likely?

A

visible moisture in the form of clouds, dew, or fog

ideal conditions for carburetor icing

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13
Q

What factor primarily determines the type and vertical extent of clouds?

A

the stability of the atmosphere

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14
Q

Define WS

A

SIGMET
valid 4 hours or 6 hours (tropical cyclones and volcanic ash)

  • severe icing not associated with thunderstorms
  • sever or extreme turbulence or clear air turbulence (CAT) not associated with thunderstorms
  • widespread dust storms or sandstorms lowering surface visabilities to below 3 miles
  • volcanic ash
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15
Q

Effects of stable and unstable air on clouds

A

stable : stratiform

unstable: cumuliform

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16
Q

Effects of stable and unstable air on turbulence

A

Stable: smooth

Unstable: rough

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17
Q

Significant precipitation is occuring at the surcace. How thick can you expect the clouds to be?

A

precipitation usually requires clouds to be at least 4,000’ thick

the heavier the precipitation, the thicker the clouds

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18
Q

During your preflight planning, what type of meteorological information should you be aware of with respect to icing?

A
  • location of fronts
  • cloud layers
  • freezing layers
  • air temperature and pressure
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19
Q

What does GFA stand for?

A

Graphical Forcast for Aviation

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20
Q

What are the three stages of a thunderstorm?

A

Cumulus stage

  • updrafts cause raindrops to increase in size

Mature stage

  • rain at earth’s surface
  • it falls through or immediately beside updrafts
  • lightning
  • possible roll clouds

Dissipating stage

  • downdrafts and rain begins to dissipate
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21
Q

LIFR Minimums

A

Low Instrument Flight Rules

ceiling: less than 500’
visibility: less than 1 mile

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22
Q

Define CWA

A

center weather advisories

valid for 2 hours

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23
Q

VFR Minimums

A

Visual Flight Rules

ceiling: greater than 3,000’
visibility: greater than 5 miles

(sky clear included)

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24
Q

Define DUATS

A

Direct User Access Terminal System

for obtaining preflight briefings and inflight weather information

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25
Q

Define DUATS II

A

Lockheed Martin Flight Services

for obtaining preflight briefings and inflight weather information

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26
Q

Define TWEB

A

Transcribed Weather Broadcast

(used in Alaska)

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27
Q

What types of weather briefings are available from a FSS?

A

standard briefing

abbreviated briefing

outlook briefing (6 or more hours before departure)

inflight briefing

28
Q

What information should a weather briefing include?

A
  • adverce conditions
  • VFR flight not recommended
  • synopsis
  • current conditions
  • enroute forecast
  • destination forecast
  • winds aloft
  • NOTAMs
  • ATC delay
  • others upon request
29
Q

What does HIWAS stand for?

A

Hazardous In-flight Weather Advisory Service

30
Q

Name several types of fog

A

radiation fog

advection fog

upslope fog

frontal fog (precipitation-induced)

steam fog

31
Q

Define WA

A

AIRMET
valid for 6 hours

  • extensive moutain obscuration
  • turbulence
  • strong surface winds
  • icing
  • freezing levels
32
Q

Effects of stable and unstable air on visibility

A

stable: fair to poor
unstable: good

33
Q

What causes Radiation Fog?

A

the ground cools the adjacent air to the dew point

(calm, clear nights)

34
Q

General characteristics of weather near a cold front

A
  • towering cumulus or cumulonimbus
  • heavy rain
  • lightning
  • thunder and/or hail
  • tornadoes
  • poor visibility
  • variable winds and gusting
  • temperature drop
  • dew point drop
  • pressure drop
35
Q

What is a Trough?

A
  • elongated area of relatively low atmospheric pressure
  • at the surface when air converges into a low, it cannot go outward against the pressure gradient, nor can it go downward into the ground, it must go upward
  • area of rising air
  • cloudiness and precipitation
  • low pressure and bad weather
36
Q

Characteristics of Advection Fog

A
  • results from the transport of warm humid air over a cold surface
  • forms primarily along coastal areas during the winter
  • may occur with winds
  • may occur with cloudy skies
  • over a wide geographic area
  • any time of the day or night
37
Q

Two basic ways fog may form:

A

cooling air to the dew point

adding moisture to air near the ground

38
Q

What factors must be present for a thunderstorm to form?

A

sufficient water vapor

an unstable lapse rate

an initial upward boost (to start the storm process)

39
Q

Characteristics of Upslope Fog

A
  • forms as a result of moist, stable air being cooled adiabatically as it moves up sloping terrain
  • once wind ceases, fog dissipates
  • quite dense
  • extends to high altitudes
40
Q

Define Wind Shear

A
  • the rate of change of wind velocity (direction and/or speed) per unit distance
  • expressed as vertical or horizontal wind shear
  • occurs at any level in the atmosphere
41
Q

Name the main types of icing an aircraft may encounter in-flight.

A

structural

induction

instrument

42
Q

What does ADS-B stand for?

A

Automatic Dependent Surveilance - Broadcast

43
Q

Types of PIREPs:

A

UA - routine

UUA - urgent

44
Q

Effects of stable and unstable air on precipitation.

A

stable: steady
unstable: showery

45
Q

What does AWOS stand for?

A

Automated Weather Observing System

46
Q

What does ASOS stand for?

A

Automated Surface Observing System

47
Q

What does AWSS stand for?

A

Automated Weather Sensor System

48
Q

What does FA stand for?

A

Aviation Area Forcast

49
Q

Define WST

A

Convective SIGMET
valid 2 hours

  • severe or greater turbulence
  • severe icing
  • low-level wind shear
  • issued hourly at H+55 (special bulletins any time)
  • Severe thunderstorm due to:
    • surface winds >50kts
    • hail >¾”
    • tornadoes
  • Embedded thunderstorms
  • A line of thunderstorms
  • Thunderstorms producing heavy precipitation that affects 40% or more of an area at least 3,000 square miles
50
Q

Occurs when a mass of cold, dense, and stable air advances and replaces a body of warmer air

A

Cold Front

51
Q

When the forces of two air masses are relatively equal, the boundary or front that separates them

A

stationary front

52
Q

What does TIBS stand for?

A

Telephone Information Briefing Service

53
Q

What does TAF stand for and what are the types?

A

Terminal Aerodrome Forcast

TAF: routine forcast

TAF AMD: amended forcast

TAF COR: corrected forcast

54
Q

The types of inflight aviation weather advisories

A

SIGMET

Convective SIGMET

AIRMET

Center Weather Advisory

55
Q

IFR Minimums

A

ceiling: 500’ - 1,000’
visibility: 1 - 3 miles

56
Q

When isobars are relatively close together on a surface weather chart or a constant pressure chart:

A

steep pressure gradient exists

high wind speeds

57
Q

Define the three types of structural icing that may occur in flight.

A

Clear Ice

Forms after initial impact when the remaining liquid portion of the drop flows over the aircraft surface, gradually freezing as a smooth sheet of solid ice

Rime Ice

Forms when drops are small (stratified clouds or light). The liquid portion remaining after initial impact freezes rapidly before the drop has time to spread out over aircraft surface

Mixed Ice

Forms when drops vary in size or when liquid drops are intermingles with snow or ice particles. The ice particles become imbeded in clear ice building a very rough accumulation.

58
Q

Occurs when a fast-moving cold-front catches up with a slow-moving warm front.

A

Occluded Front

59
Q

3 areas of special concern for wind shear:

A
  • wind shear with a low-level temperature inversion
  • wind shear in a frontal zone or thunderstorm
  • clear air turbulence (CAT) at high levels (associated with a jet stream or strong circulation)
60
Q

What does FIS-B stand for?

A

Flight Information Service - Broadcast

61
Q

Types of AIRMETs:

A

Sierra

  • describes IFR conditions and/or extensive mountian obscurations

Tango

  • moderate turbulence
  • sustained surface winds greater than 30kts
  • nonconvective low-level wind shear

Zulu

  • moderate icing
  • freezing level hights
62
Q

What does FB stand for?

A

winds and temperatures aloft forcasts

63
Q

Examples of NWS weather charts you will use during preflight planning

A

S surface analysis chart

W weather depiction chart

S short-range surface prognostic chart

S significant weather prognostic chart

C convective outlook chart

C constant pressure analysis chart

64
Q

What causes the winds aloft to flow parallel to the isobars?

A

The Coriolis Force

65
Q

State the general characteristics in regard to the flow of air around high and low pressure systems in the northern hemisphere

A

low pressure: inward, upward, counterclockwise

high pressure: outward, downward, clockwise

CMEL (4 decks)

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