C. Weather Info Flashcards

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1
Q

What is atmospheric stability?

A

Is the property of ambient air that either enhances or suppresses vertical motion of air parcels and determines which type of clouds and precipitation a pilot will encounter.

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2
Q

What is a surface analysis chart?

A

Surface analysis charts are analyzed charts of surface weather observations. The chart depicts the distribution of several items including sea level pressure, the position of highs and lows, ridges, troughs, the location and character of fronts, and the various boundaries such as dry lines, outflow boundaries, sea-breeze fronts, and convergence lines.

The chart is produced eight times daily.

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3
Q

How does the air flow around high and low pressure systems in the N. hemisphere?

A

Low Pressure - inward, upward, and counterclockwise

High Pressure - outward, downward, and clockwise

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4
Q

What kind of weather can you expect in a low-pressure system? In a high-pressure system?

A

A low-pressure system is characterized by rising air, which is conductive to cloudiness, precipitation, and bad weather.

A high-pressure system is an area of descending air which tends to favor dissipation of cloudiness and good weather

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5
Q

What are the type of fronts?

A

Cold front - cold air replaces warm air.
Speed - 20-35 mph… steeper frontal slope… cold fronts typically have violent wx.

Warm front - warm air replaces cold air.
10-25 mph… low ceilings, poor visibility, and rain.

Stationary front - when cold and warm pushes against each other.

Occluded front - cold front catches warm front and are moving in same direction.

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6
Q

What are the general weather characteristics near a cold front and a warm front?

A

Cold Front - towering cumulus or cumulonimbus, heavy rain accompanied by lightning, thunder and/or hail; tornadoes possible; during passage, poor visibility, winds variable and gusting; temp/dew point and pressure drop rapidly.

Warm Front - stratiform clouds, drizzle, low ceilings, and poor visibility; variable winds; rise in temp.

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7
Q

What is a trough?

A

A trough, called a trough line, is an elongated area of relatively low atmospheric pressure.

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8
Q

What is a ridge?

A

A ridge, also called a ridge line, is an elongated area of relatively high atmospheric pressure.

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9
Q

What is the standard temp. and pressure?

A

15 C (59 F) 29.92 Hg

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10
Q

What are short-range surface prognostic charts?

A

Short-range prog charts provide a forecast of surface pressure systems, fronts and precipitation for a 2.5 day period. Conditions are divided into 5 forecast periods: 12, 18, 24, 48, and 60h.

Issued 4 times daily and can be used to obtain the progression of surface weather during the included periods

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11
Q

What are isobars?

A

An isobar is a line on a weather chart which connects areas of equal or constant barometric pressure.

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12
Q

What is indicated by isobars being close together?

A

When isobars are spaced very close together, a steep pressure gradient exists which indicating higher wind speeds. A shallow pressure gradient usually means winds will be calmer.

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13
Q

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

A

The Coriolis force.

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14
Q

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

A

Surface friction

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15
Q

What is a METAR and what are the two types?

A

A METAR is an hourly surface observation of conditions observed at an airport.
There are two types of METAR reports.
METAR report every hour.
SPECI is an amended observation for weather.

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16
Q

What are TAFs?

A

A terminal aerodrome forecast is a weather forecast.

TAFs are issued at least four times a day, every six hours usually covering 24-30 hours.

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17
Q

What is AIRMET? (STZ)

A

PHAK 13
Airmens Meteorological Information
Issued every 6 hours
Potentially hazardous to light aircraft

Sierra: IFR, extensive mountain obscuration
Tango: turbulence, strong surface winds > 30 knots, non-convective low-level wind shear
Zulu: icing, and freezing levels

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18
Q

What is a SIGMET? (SSSDV)

A

PHAK 13-12/AIM 7-1-6
Significant Meteorological
Non convective weather potentially hazardous to all aircraft
Not associated with thunderstorms
Valid for 4 hours or 6 hours for hurricanes

Severe icing not associated with thunderstorms
Severe or extreme turbulence or CAT not associated with a t-storm
Sandstorms lowering surface visibilities to below 3 miles
Duststorms lowering surface visibilities to below 3 miles
Volcanic ash

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19
Q

Convective SIGMET?

6 thunderstorm reasons (SHLEPT)

A

AIM 7-1-6
Hazardous to all aircraft.
2 hours
Severe thunderstorms due to:
1. Surface winds greater than or equal to 50 knots
2. Hail at surface greater than or equal to 3/4 in. in diameter
3. Tornadoes
4. Embedded thunderstorms
5. Line of thunderstorms
6. precipitation affecting 40% or more of 3,000 sq.mi.

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20
Q

What factors must be present for a thunderstorm to form?

A

Water vapor
Unstable atmosphere
Upward drafts

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21
Q

What does dew point mean?

A

Dew point is the temperature to which a sample of air must be cooled to attain the state of saturation.

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22
Q

When temperature and dew point are close together, within 5 degrees, what can you expect?

A

Visible moisture in the form of clouds or fog.

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23
Q

Define LIFR, IFR, MVFR, VFR:

A

LIFR - Low IFR ceiling less than 500’ and/or visibility less than 1 miles
IFR - Ceiling 500’ to less than 1,000’ and visibility 1 to less than 3 miles
MVFR - ceiling 1,000-3,000’ and/or visibility 3-5 miles inclusive
VFR - ceiling greater than 3,000’ and visibility greater than 5miles including clear sky

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24
Q

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

A

1” Hq per 1,000 Feet

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25
Q

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

A

The stability of the atmosphere.

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26
Q

What is atmospheric stability?

A

The stability of the atmosphere depends on its ability to resist vertical motion.

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27
Q

List the effects of stable and unstable air on clouds, turbulence, precipitation and visibility:

A
Stable:
Clouds: Stratiform
Turbulence: Smooth
Precipitation: Steady
Visibility: Fair to Poor
Unstable
Clouds: Cumuliform
Turbulence: Rough
Precipitation: Showery
Visibility: Good
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28
Q

When significant precipitation is occurring at the surface, how thick can you expect the clouds to be?

A

Significant precipitation usually requires clouds to be at least 4,000 feet thick. The heavier the precipitation, the thicker the clouds are likely to be.

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29
Q

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

A

Location of fronts - A front’s location, type, speed, and direction of movement.

Cloud layers - The location of cloud bases and tops, which is valuable when determining if you will be able to climb above icing layers or descend beneath those layers into warmer air; reference PIREPs and area forecasts.

Freezing levels - Important when determining how to avoid icing and how to exit icing conditions if accidentally encountered.

Air temperature and pressure - Icing tends to be found in low-pressure areas and at temperatures at or around freezing.

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30
Q

What is the definition of the term freezing level and how can you determine where that level is?

A

The freezing level is the lowest altitude in the atmosphere over a given location at which the air temperature reaches 0 degrees C.

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31
Q

What conditions are necessary for structural icing to occur?

A

Visible moisture and below freezing temp at the point moisture strikes the aircraft.

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32
Q

What are the main types of icing an aircraft may encounter in-flight?

A

Structural, induction, and instrument icing.

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33
Q

What types of structural icing may occur in flight?

A

Clear ice - forms after initial impact when the remaining liquid portion of the drop flow out over the A/C surface, gradually freezing as a smooth sheet of solid ice

Rime ice - forms when drops are small, such as those in stratified clouds or light drizzle. The liquid portion remains after initial impact freezes rapidly before the drop has time to spread out over the A/C surface

Mixed ice - forms when drops vary in size or when liquid drops are intermingled with snow or ice particles. The ice particles become imbedded in clear ice, building a very rough accumulation

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34
Q

What action is recommended if you inadvertently encounter icing conditions?

A

The first course of action should be to leave the area of visible moisture. This might mean descending to an altitude below the cloud bases, climbing to an altitude above the cloud tops, or turning to a different course. Turn on pitot heat.

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35
Q

Is frost considered to be hazardous to flight? Why?

A

Yes, because while frost does not change the basic aerodynamic shape of the wing, the roughness of its surface spoils the smooth flow of air, thus causing a slowing of airflow. This slowing of the air causes early airflow separation, resulting in a loss of lift.

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36
Q

What are the three stages of a thunderstorm?

A

Cumulus stage - Updrafts causing raindrops to increase in size.

Mature stage - Rain at earth’s surface; it falls through or immediately besides the updrafts; lightning; perhaps roll clouds .

Dissipating stage - Downdrafts and rain begin to dissipate.

37
Q

What is a temperature inversion?

A

An inversion is an increase in temperature with height - a reversal of the normal decrease with height.

38
Q

State two basic ways that fog may form?

A

Cooling air to the dew point.

Adding moisture to the air near the ground.

39
Q

What are the different types of fog? USAIRF

A
Upslope
Steam
Advection
Ice
Radiation
Frontal fog / precipitation-induced fog
40
Q

What causes radiation fog to form?

A

The ground cools the adjacent air to the dew point on clam, clear nights.

41
Q

How does advection fog form?

A

Advection for results from the transport of warm humid air over a cold surface. A pilot can expect advection for to form primarily along coastal areas during the winter.

42
Q

What is upslope fog?

A

Upslope fog forms as a result of moist, stable air being cooled adiabatically as it move up sloping terrain. Upslope fog is often quite dense and extends to high altitudes.

43
Q

What is wind shear and when is it likely to occur?

A

Wind shear is a change in wind speed and/or direction over a short distance.

Wind shear with a low-level temp. inversion.
Wind shear in a frontal zone or thunderstorm.
Clear Air Turbulence at high levels associate with a jet stream or strong circulation.

44
Q

Why is wind shear an operational concern to pilots?

A

Wind shear is an operational concern because unexpected changes in wind speed and direction can be potentially very hazardous to aircraft operations at low altitudes on approach to and departing from airports.

45
Q

What type of weather information will you examine to determine if wind shear conditions might affect your flight?

A

Terminal forecasts - any mention of low level wind shear or the possibility of severe thunderstorms, heavy rain showers, hail, wind gusts suggest the potential for LLWS and microbursts

METARS - inspect for any indication of thunderstorms, rain showers, or blowing dust. Additional signs such as warming trends, gusty winds, cumulonimbus clouds, etc. should be noted

Severe weather watch reports - SIGMETS and convective SIGMETs severe convective weather is a prime source for wind shear and microbursts

LLWS reports - installed at 110 airports in the US; designed to detect wind shifts between outlying stations and a reference centerfield station

PIREPs - reports of sudden airspeed change on departure or approach and landing corridors provided a real-time indication of the presence of wind shear

46
Q

What is the primary means of obtaining a weather briefing?

A

Flight Service Station (1-800-WX-BRIEF)

Foreflight

47
Q

What type of weather briefings are available?

A

Standard briefing - Request when you are planning a flight and you have not received a previous briefing or have not received preliminary information through mass dissemination media.

Abbreviated Briefing - Request when you need information to supplement mass disseminated data, update a previous briefing, or when you need only one or two items.

Outlook Briefing - Request whenever your proposed time of departure is six or more hours from the time of the briefing; for planning purposes only.

Inflight Briefing - Request when needed to update a preflight briefing.

48
Q

What pertinent information should a weather briefing include?

A
Adverse Conditions
VFR Flight not recommended
Synopsis
Current conditions
Enroute forecast
Destination forecast
Winds aloft
NOTAMs
ATC delay
49
Q

What is HIWAS?

A

Hazardous In-flight weather advisory service is a continuous broadcast of in-flight weather advisory including summarized aviation weather warnings, SIGMET, Convective SIGMET, Center Weather Advisory, AIRMET, and urgent PIREPs. HIWAS is an additional source of hazardous weather information which makes this data available on a continuous basis.

50
Q

What is a flight information service?

A

FIS is a ground broadcast service provided through the Automatic Dependent Surveillance Broadcast (ADS-B) The system provides pilots and flight crews of properly-equipped aircraft with a flight deck display of aviation weather and aeronautical information.

51
Q

Can onboard datalink weather FIS-B be useful in navigating an aircraft safely around an area of thunderstorms?

A

Weather data linked from a ground weather surveillance radar system is not real-time information; it displays recent rather than current conditions. This data is typically updated every 5 minutes, but can be as much as 15 minutes old by the time it displays in the cockpit. Not the best for tactical avoidance of severe weather such as negotiation a path through a weather hazard area.

52
Q

While en route, how can a pilot obtain updated weather information?

A

FSS
ATIS broadcast along your route of flight
ATC workload permitting

53
Q

Describe the basic elements of a METAR.

A

Meteorological Terminal Air Report is an observed weather report.
Observed weather updated every 1 hour.
SPECI is amended METAR.

54
Q

What types of weather observing programs available?

A

Manual Observations - with only a few exceptions these reports are from airport locations staffed by FAA personnel who manually observe, perform calculations, and enter their observations into the communication system

AWOS - Automated weather observing system; consists of various sensor, a processor, a computer-generated voice subsystem, and a transmitter to broadcast local, minute-by-minute weather data directly to the pilot.

ASOS/AWSS - Automated Surface Observing System / Automated Weather Sensor System; the primary US surface weather observing system. AWSS is a follow-on program that provides the identical data as ASOS. Both systems provide continuous minute-by-minute observations that generate METARs and other aviation weather information. Transmitted over a discrete VHF radio frequency or the voice portion of a local NAVAID, and are receivable to a maximum of 25 NM from the station and a maximum altitude of 10,000 AGL.

55
Q

Define aviation area forecast.

A

Abbreviated as FA, this is a forecast of specified weather phenomena covering a flight information region or other area designated by the meteorological authority.
FAs are issued 3 times daily for each of the 6 areas in the contiguous 48 states.

FAs are also issued for the Gulf of Mexico, Caribbean, Hawaii, and Alaska. More area forecast were canceled in 2017 replaced by GFA

56
Q

What information is provided by FA?

A

Area forecasts are issued for the conterminous US and cover the airspace between the surface and 45,000 feet AMSL. They include

Synopsis
Clouds and weather description of the clouds and weather for the first 12-h period for each state or group of states including
Cloud amount
Cloud bases and tops
Precipitation
Visibilities between 3 and 6 SM
Sustained surface winds 20 knots or greater
12 to 18 hour categorical outlook - IFR, MVFR, VFR

57
Q

What is a Graphical Forecast for Aviation (GFA)?

A

The GFA is intended to provide the necessary aviation weather information as a complete picture of the weather that may impact flight in the US. The webpage includes observational data, forecasts, and warnings that can be viewed from 14h in the past to 15h in the future, including thunderstorms, clouds, flight category, precipitation, icing, turbulence and wind.

58
Q

Describe the winds and temperature aloft forecasts.

A

Wind and temp aloft forecasts are computer prepared forecasts of wind direction, speed, and temperature at specified times, altitudes, and locations. They are produced 4 times daily.

Wind direction in tens of degrees, two digits, with reference to true north and wind speed is given in knots.

59
Q

What are PIREPs (UA) and where are they usually found?

A

A pilot report provides conditions as they actually exist in the air, which cannot be gathered from any other source.
Pilots can confirm the height of bases and tops of clouds, locations of win shear and turbulence, and the location of inflight icing. There are two types of PIREPs; routine UA and urgent UUA.
PIREPS are available from an FSS and on the internet via the ADDS web page

60
Q

What valuable information can be determined from winds and temp aloft forecasts?

A

Most favorable altitude based on wind and direction of flight

Areas of possible icing by noting air temp of 2 to -20 C

Temperature inversion

Turbulence by observing abrupt changes in wind direction and speed at different altitudes

61
Q

Give some examples of NWS(national weather service) weather charts you will use during preflight planning.

A
Surface analysis chart
Weather depiction chart
Short-range surface prognostic chart
Significant weather prognostic chart
Convective outlook chart
Constant pressure analysis chart
62
Q

What is a convective outlook chart?

A

The convective outlook chart depicts ares of forecast to have the potential for sever tornado, wind gust 50 kt or more, or hail 3/4” or greater and non-sever general convection and specific sever weather threats during the following 3 days. The chart defines areas of slight risk SLGT, moderate risk MDT, or high risk HIGHT of severe thunderstorms for a 24-h period beginning at 1200 UTC.

63
Q

What atmospheric factor causes rapid movement of surface fronts?

A

Upper winds blowing across the front

64
Q

Where is the normal location of the jet stream relative to surface lows and fronts?

A

The jet stream is normally located north of the surface systems.

65
Q

What type of icing is associated with the smallest size of water droplet similar to that found in low level stratus clouds?

A

Rime ice forms when drops are small such as those in level stratus clouds

66
Q

What condition is necessary for the formations of structural icing in flight?

A

Flying through visible moisture and the temperature where the water strikes the aircraft must be freezing

67
Q

What condition is indicated when ice pellets are encountered during flight?

A

Freezing rain at higher levels

68
Q

When will frost most likely form on aircraft surfaces?

A

When both the temperature and dew point are below freezing. Occurs on clear nights with little or no winds.

69
Q

What is and where do squall lines most often develop?

A

A narrow band of active thunderstorms, develops ahead of a cold front in moist unstable air.

70
Q

Which types storms are most likely to produce funnel clouds or tornadoes?

A

Steady state (frontal) thunderstorms

71
Q

You are observing cumulonimbus mamma clouds. What inference can be made to this sighting?

A

Violent thunderstorms and tornadoes, turbulence.

72
Q

Where is the greatest area of thunderstorm turbulence?

A

Under the anvil

73
Q

What is the recommended flight separation from thunderstorms?

A

+20 miles

74
Q

At what altitude of cloud tops should a thunderstorm be considered extremely hazardous?

A

Tops above 35,000ft

75
Q

What changes will you notice after crossing a front?

A

Temperature, wind speed and direction, and humidity will change rapidly over a short distance.

76
Q

What in-flight hazards are associated with thunderstorms?

A
Turbulence
Lightning
Icing
Hail
Low ceiling, low visibility
Wind shear
Microbursts
77
Q

What would you do if you entered a thunderstorm?

A

Tighten safety belt and harness
Plan course to take you through the storm in a minimum amount of time (and hold that course)
Turn on pitot heat
Use power settings for reduced turbulence airspeed recommended in aircraft manual.
Turn up cockpit lights to lessen temporary blindness caused by lightning
Keep eyes on instruments
Don’t change power settings
Maintain constant attitude
Don’t turn back once in the thunderstorm

78
Q

What is our atmosphere made of?

A

PHAK 12-2/AC 00-06b
78% nitrogen
21% oxygen
1% of Argon/Carbon Dioxide and other trace gases

79
Q

How do weather systems form?

A

Water to vapor rises

  1. Evaporation - liquid to vapor
  2. Transpiration - liquid from plants to vapor
  3. Sublimation - solid to vapor (snow, ice to vapor)
  4. Condensation - vapor condenses to a cloud
  5. Transportation - wind pushes it
  6. Precipitation - rain, snow, ice, mist… that falls to the earths surface
80
Q

What are Air Masses?

A

00-06b 10-1
Is a large body of air with generally uniform temperature and humidity.
Source Region- is where an air mass originated from.

81
Q

How many air masses are there and what are they?

A
00-06b 10-1
There are 5 types.
3 continental- which means dry air masses that developed over land.
cA - Continental Arctic
cP - Continental Polar
cT - Continental Tropical
2 Maritime- which means moist air that developed over water.
mP - Maritime Polar
mT - Maritime Tropical
82
Q

What are the different kinds of atmospheric stability, or air parcels?

A

Stable parcel - if the lifted parcel is colder than surrounding air it will be denser than the surrounding air and sink back to its original state.
Neutral parcel - if lifted parcel is same temperature as air it will be the same density and remain at the same level.
Unstable parcel - if lifted parcel is warmer therefore less dense than surrounding air, it will rise on its own until it reaches same temperature as its environment.

83
Q

What are the wind forces, or what makes the wind move?

A

00-6B ch. 7
1. Pressure Gradient Force (PGF)
Wind falls from high pressure to lower pressure… like a stream going down hill.
2. Coriolis Force
The earth spinning effects the wind. Note: north of equator pushes wind to the right. South of equator pushes wind to the left.
3. Friction
Whenever the wind hits the surface, it slows the wind down.

84
Q

What is the vertical structure of the atmosphere? Or what are the various atmospheres?

A

Earth surface to space

  1. Troposphere- vast majority of weather happens.
  2. Tropopause - up to 48,000 feet in height, but varies with season.
  3. Stratosphere - temperature gets warmer due to absorption of ultralight radiation
  4. Stratopause - gets up to negative 3 degrees Celsius.
  5. Mesosphere - gets colder
  6. Mesopause - down to negative 100 degrees Celsius.
  7. Thermosphere - temp increases with height
  8. Thermopause
  9. Exosphere - atoms an molecules escape to space, satellite orbit earth.
85
Q

Microbursts indications and attributes:

A

PHAK 12-11
Indication: intense rain shaft at the surface but Virga at the cloud base and a ring of blowing dust is often the visual clue.
Note: virga is the evaporation of precipitation before it reaches the earths surface.
Attributes: 1-2 miles in diameter. Depth of 1000 ft. Lifespan is 5-15 min. Downdrafts up to 6000 ft. Per. Min. (FPM). Headwind loss of 30-90 knots.

86
Q

Cloud types

A
Low clouds: sfc-6500ft.
1. Stratus 2. Stratocumulus 3. Nimbostratus
Middle clouds: 6500-20,000ft.
1. Altostatus 2. Altocumulus
High clouds: above 20,000 ft.
1. Cirrostratus 2. Cirrocumulus 3. Cirrus
Vertical development clouds:
1. Towering cumulus 2. Cumulonimbus
87
Q

Obstructions to visibility include?

A
Fog
Mist
Haze
Smoke
Precipitation
Blowing snow
Dust storm
Sandstorm
Volcanic ash
(Definitions are in 00-6B ch. 16)
88
Q

How do you read wind charts?

A

By the barbs, small bard indicates 5, big barb 10, triangle 50.