Section 3: Weather Information Flashcards
What is a METAR? How often are they issued and how long are they valid for?
An observation of CURRENT surface weather; issued hourly and is valid until next issuance.
What is a SPECI? How long are they valid for?
Special Weather Report (SPECI): special issuance, valid until next issuance
What is a TAF? How often are they issued and how long are they valid for?
forecasted weather within a 5nm radius from the airport; issued every 6 hours (4 times a day), and is valid 24-30 hours.
What is a surface analysis chart and what does it SHOW?
A chart of the current surface weather.
It shows:
1. areas of high and low pressure
2. fronts
3. temperatures (in degrees F) and dew-points
5. wind directions and speeds
6. visual obstructions
How often are surface analysis charts issued and how long are they valid for?
Issued every 3 hours; valid at observation
What is a radar summary chart? How often are they issued?
Weather product derived from the national radar network that graphically displays a summary of radar weather reports; issued HOURLY as a summary
What does a low-level prognostic chart show? How long are they valid for?
combines forecasts of fronts, isobars, and high/low pressure systems; valid at time on chart
What does a winds and temperatures aloft chart show?
shows wind speed/direction and temperature at different altitudes. (winds are not reported at levels within 1500 feet of location’s elevation; temp forecasts not reported for levels within 2500 feet of location’s elevation)
How often is a winds and temperatures aloft chart issued and how long is it valid for?
- Issued every 4 hours
- Valid for either 6,12, or 24 hours
What are troughs?
Elongated areas of low pressure
What is an advisory circular and where can you find these?
Advisory material the FAA sends out, and they can go into depth about types of weather. You can find them online and look up any type of AC you need (ex: thunderstorms)
What do you get in a standard weather briefing?
TAFs, METARs, Winds and Temps Aloft, Surface Analysis Chart, Prognosis Chart, NOTAMs and TFRs (temporary flight restrictions)
Where can you find METARs and TAFs?
Foreflight, Aviationweather.gov, or by texting 358-782
What are PIREPs and how do they report about wind shear?
PIREPs are pilot reports submitted to the FSS, depicting real time weather conditions.
Report about wind-shear as a loss/gain in altitude/airspeed
What is a Weather Depiction Chart and how often are they issued, as well as how long are they valid for?
- Details surface conditions as derived from METAR ad other surface observations.
- Issued every 3 hours
- Valid at observation
How can you get weather before a flight?
- Call 1-800 wxbrief and get a weather briefing
- Look at METARs or TAFs
- Look at surface analysis charts, winds and temps aloft charts
- Use GFA tool on aviationweather.gov ( you can plot your flight and it will tell you the weather along the way)
What should you look at in order to get current weather?
METARs
How can you get weather while en route?
- Use Flight Service Stations
- You can also listen to AWOS as you go, but this is not the best option if you’re trying to plan for weather further than 30 miles out.
What are AIRMETs and who are they intended for?
- Adverse weather conditions that MAY affect safety of flight (other than convective activity)
- Intended for all pilots as a safety precaution
How often are AIRMETs issued, and how long are they valid for?
Issued as needed; valid for 6 hours
What are the three types of AIRMETs and what is each specifically for?
- Sierra- mountain obscurations, IFR conditions
- Tango- moderate turbulence, surface winds of 30 knots or greater, and/or non-convective wind-shear
- Zulu- moderate icing, info about freezing levels
How do you make a PIREP?
Give information to FSS or ATC if not too busy
What is a SIGMET, how long are they valid for and when are they issued?
- adverse weather conditions that will likely affect safety of flight (for all aircraft)
- issued as needed
- valid for 4 hours (6 if hurricane)
What are SIGMETs issued for?
- Severe or clear-air turbulence
- Severe icing not associated with thunderstorms
- Dust/sand storm that lowers visibility below 3 sm
- Volcanic ash
What are CONVECTIVE SIGMETs, how long are they valid for and when are they issued?
- Issued for any convective situation that the forecaster feels is hazardous to all aircraft
- Issued as needed
- Valid for 2 hours (updated hourly)
What is implied in a CONVECTIVE SIGMET?
implied severe turbulence, icing, and low level wind shear
In what conditions would a CONVECTIVE SIGMET be issued for (6)?
- Hail 3/4 inches in diameter or greater
- Embedded thunderstorms
- Tornadoes
- Surface winds greater than 50 knots
- Thunderstorms covering at least 40% of a 3000 square mile area
- Squall lines
What is windshear? What does it do to aircraft?
a sudden, drastic change in wind direction and/or wind speed over a very small area. It can rapidly change the performance of an aircraft.
What are mountain waves? What do these create?
mountains cause winds blowing across them to oscillate from their equilibrium; creates violent downdrafts and updrafts, turbulence, and strong shear and rotor zones.
What kinds of clouds are generally associated with mountain waves?
Lenticular clouds
What do isobars indicate? What does it mean if isobars are close together?
Indicate areas of similar pressure; isobars close together= turbulence (a high gradient of pressure can mean there are strong winds, while a low pressure gradient means weak winds)
Where does turbulence come from?
pressure, obstructions on the ground, uneven heating of the Earth’s surface
What is density altitude made up of?
altitude, moisture, and temperature
What is density altitude?
Pressure altitude corrected for nonstandard temperature
At higher altitudes, is the air more or less dense? How does this affect our performance?
High altitude= less dense; causes poor performance
At lower altitudes, is the air more or less dense? How does this affect our performance?
Low altitude= more dense; causes better performance (gives more thrust in the engine because of the air molecules and more authority for the air foils)
Is hot air more or less dense than cold air? How does this affect our performance?
Hot air is less dense; which causes poor performance (better performance in cold air)
Is moist air more or less dense than dry air? How does this affect our performance?
Moist air is less dense than dry air; causes poor performance (better performance in dry air)
What is pressure altitude?
height above standard datum plane (29.92)
Would high density altitude cause poor or good performance on our aircraft? How come?
High density altitude= poor performance; causes less thrust and we would climb more slowly and possible not as high as usual.
How would a high density altitude affect takeoff performance?
It could cause a longer takeoff roll and slower climb, which could result in not being able to clear an obstacle.
What is standard temperature and pressure?
Standard temp= 15 degrees Celsius
Standard pressure = 29.92
What are the ingredients for structural icing?
- Visible moisture
- Temperatures near freezing
What are the types of structural icing? Explain them.
- Rime ice= like the ice that gathers in our freezer (freezes instantly on impact with an aircraft)
- Clear ice= most dangerous (has time to slide, freezes not instantly on impact with an aircraft)
- Mixed ice= a mix of clear and rime ice
What are microbursts?
-strong downdrafts (up to 6000 fpm) from convective activity within a small area
- usually last 15 minutes
-spread outwards once they hit surface, which causes vertical and horizontal wind shears
-1-2 miles in diameter
Dewpoint
temperature where the air is going to be fully saturated and we will have visible moisture (fog, rain, ice, clouds , snow, etc.)
What is fog? What causes fog to form?
a cloud on the surface; when the temperature meets the dewpoint