Weather Information Flashcards
What weather sources do you use to obtain the weather information regarding your flight?
- Flight Service Station
- Aviation Weather Center
- Call the weather briefer
- ForeFlight
- ATIS
- ATC
What weather products do you use to obtain the weather information regarding your flight?
- AIRMETs
- SIGMETs
- Convective SIGMETs
- PIREPs
- METARs
- TAFs
- Surface Analysis Chart
- Wind & Temp aloft forecasts
- Low level significant weather chart
- Ceiling & visibility charts
What is a METAR?
When is it issued?
- An observation of current surface weather reported in a standard international format
- Issued hourly
What is a TAF?
When is it issued?
- A concise statement if the expected meteorological conditions significant to aviation for a specified time period within 5 SM of the center of the airports runway
- Issued every 6 hours
What is a Surface Analysis Chart?
What does it show?
When is it issued?
- A chart that depicts an analysis of the current weather
- Shows areas of high and low pressure, fronts, temperatures, dew-points, wind directions and speeds, local weather and visual obstructions
- Issued every 6 hours and valid 24-30 hours
What is a Weather Depiction Chart?
What does it show?
When is it issued?
- Shows details from METAR and other surface observations
- Issued every 3 hours
What is a Radar Summary Chart?
When is it issued?
- Graphically displays a summary of radar weather reports
- Issued hourly
What is a low-level prognostic chart?
When is it issued?
- A chart that combines forecasts of fronts, isobars and high/low pressure systems
- Issued 4 times a day
What is the Winds and temperatures aloft chart?
When is it issued?
When are negative temps implied?
How do you solve is wind is greater than 99 kts? Ex. 794358
When are winds not reported?
When are temps not reported?
- A chart that shows wind speed, wind direction and temperatures at different altitudes
- Issued every 6 hours, valid for 6, 12, or 24 hrs
- At and after FL240 temps are always negative
- Subtract 50 from wind direction 79 = 290, add 100 to wind speed 43 = 143 kts, and temp -58
- Winds not reported at levels within 1,500 ft of location’s elevation
- Temps not reported at levels within 2,500 ft of location’s elevation
What are AIRMETs?
How long are they valid for?
What are they issued for?
What are the 3 types of AIRMETs?
- Adverse weather conditions that may affect safety of flight
- Valid for 6 hours
- Issued for weather phenomena at lower intensities that are NOT SIGMETs
- AIRMET (T): Moderate turbulence, winds of 30 knots or greater, and low-level wind shear
- AIRMET (S): Mountain obscuration and IFR conditions
- AIRMET (Z): Moderate icing
What are SIGMETs?
How long are they valid for?
What are they issued for?
- Adverse weather conditions that are hazardous to all types of aircrafts
- Valid for 4 hours
- Issued for severe turbulence, severe icing, dust/sand storms that lower visibility below 3 SM, and volcanic ash
What are Convective SIGMETs?
How long are they valid for?
What are they issued for?
- Inflight advisory of convective weather significant to the safety of all aircraft that can include implied severe turbulence, severe icing, and low level wind shear
- Valid for 2 hours, updated hourly
- Issued for Hail 3/4 inch or greater, tornadoes, embedded or severe thunderstorms, surface winds greater than 50 knots, squall lines of 40% coverage and 60 NM of length, and thunderstorms covering 40% of a 3000 mile area
What is the atmosphere? What is the atmosphere composed of? What causes weather? Where does most weather occur? What are the 3 layers of the atmosphere?
- A mixture of gases that surrounds the Earth
- 78% Nitrogen, 21% Oxygen, 1% other gasses
- The uneven heating of earths surface
- Most weather occurs in the Troposphere
- Troposphere, Tropopause, Stratosphere
What is standard lapse rate?
2°C down per each 1,000 feet climbed
What is wind?
horizontal motion of air caused by atmospheric pressure differences
What is wind shear?
A sudden, drastic change in wind speed and/or direction over a very small area.
What is Mountain Wave?
Wind flowing over and around mountains create waves and turbulence dangerous to aircraft
When does moisture exist?
How does precipitation occur?
What are the types of precipitation?
- Moisture exists within the atmosphere as vapor, clouds and precipitation
- Occurs when there is sufficient water vapor, sufficient lift, and a growth process
- Freezing rain, snow, ice pellets, and rain
What are air masses?
large bodies of air that have uniform temperature, humidity, and pressure
What kind of weather are cold air masses associated with and how do they move?
Fast moving, associated with instability and good visibility
How does high pressure move?
O.C.D
Outwards
Clockwise
Downwards
What kind of weather are warm air masses associated with and how do they move?
Slow moving, associated with stability and poor visibility
How does low pressure move?
I.C.C.U
Inwards
Counterclockwise
Upwards
What are fronts?
What are the 4 types of fronts?
- A boundary between two air masses
- C.O.W.S
Cold front
Occluded front
Warm front
Stationary front
What is a cold front?
What kind of weather does it contain?
- A fast moving front with a steep slope that forces warm air up abruptly
- Narrow bands of showers and thunderstorms
What is an occluded front?
What kind of weather does it contain?
- A fast moving cold front overtaking a slow warm front
- Unstable and severe weather
What is a warm front?
What kind of weather does it contain?
- A slow moving front with a gentle slope that forces cold air up gradually
- Cirrus or stratus clouds and fog
What is a stationary front?
What kind of weather does it contain?
- Warm front and a cold front at a standstill
- Combination of cold and warm front
What are clouds?
Clouds are a large collection of very tiny droplets of water or ice crystals that condense onto tiny pieces of dust that are floating in the air. when billions of these droplets come together they become a cloud
What is turbulence?
What are kinds of turbulence exist?
-Turbulence is caused by the flow of wind being broken from its equilibrium
-Convective currents (thermals), mechanical turbulence,
temperature inversion, and clear air turbulence (CAT)
What are convective currents?
Areas of rising warm air and sinking cool air due to the uneven heating of the earths surface. These can also sometimes be know as thermals
How is mechanical turbulence caused?
Caused by obstructions such as trees, buildings, and mountains. This is what causes mountain waves
What is clear air turbulence (CAT)?
Higher altitude turbulence associated with wind-shear. caused mostly by jet streams. Most common in winter where jet streams are strongest
What are thunderstorms?
A storm produced by a cumulonimbus cloud that is always accompanied by lightning and thunder, strong gusts, heavy rain, and sometimes hail
What are the 3 conditions to form a thunderstorm?
- Sufficient water vapor
- An unstable lapse rate
- An uplifting force
What are the 3 stages of a thunderstorm?
- Cumulus stage: mostly updrafts
- Mature stage: when the storm is at its strongest point
- Dissipating stage: strong down drafts
What are some thunderstorm hazards
- Limited visibility
- Strong updrafts/ downdrafts
- Hail
- Wind shear
- Icing
- Heavy rain
- Severe turbulence
- Lightning and tornadoes
Name the 4 types of thunderstorms and explain each one
- Single cell: one cell
- Multicell: a cluster of cells, usually squall lines
- Supercell: has a single rotating updraft that can last many hours
- Embedded thunderstorms: Thunderstorms that can be embedded in other cloud types making it hard to see them
How do you fly through a thunderstorm?
- DO NOT fly under it or within 20 NM of it
- Advice ATC if deviation is necessary and try to land and wait it out
- If flying through the storm then turn on the anti icing equipment such as the pitot heat, fly a Va and maintain constant altitude
What is a microburst?
What are some indications of a microburst
What kind of weather does it contain?
How long does it last and what size can it reach?
- Small scale intense downdrafts of up to 6,000 FPM which spread outwards upon reaching the surface
- Intense rain at the surface, virga at a cloud base and dust halos
- They consist of both vertical and horizontal wind shears
- They usually last 15-30 minutes and can be 1-2 miles in diameter
How do you fly through a microburst?
Increase full power and try to climb out and through it
What are the 3 different types of icing?
- Structural icing
- Instrument icing
- Induction icing
Name the 3 types of structural icing and explain each and what temperatures they begin to form
- Clear icing: Clear, hard to see ice. Formed by slow freezing. (0 to -10 C)
- Mixed icing: Mixture of clear and rime ice. Forms from small scale variations of liquid water. (-10 to -15 C)
- Rime ice: Milky and opaque. Formed by instantaneous freezing of small supercooled water droplets. (-15 to -20 C)
What is instrument icing?
Icing that can occur on the pitot-static system
What is induction icing?
Icing that occurs on the induction system of an aircraft such as the air intake
What is freezing level information?
The altitude at which the temperatures are cold enough to facilitate icing
What is fog?
Clouds at the surface
Name the 4 types of fog and explain each
- Advection fog: warm, moist air over a cool surface
- Upslope fog: warm air travels up slope and cools
- Steam fog: cold air over warm surface
- Radiation fog: cool air over warm surface
What is frost?
The formation of thin ice crystals on solid objects below the freezing point that disrupt the smooth airflow over the wings which can reduce lift
Name some obstructions to visibility abs where they are reported
- Smoke, haze, volcanic ash, and dust-storms
- Smoke and haze are reported in METARs
- Volcanic ash and dust storms are reported in SIGMETs
