Weather Information Flashcards
Most of Earth’s weather occurs in what region of the atmosphere?
Troposphere (SFC to 36,000 ft)
What are the standard temperature and pressure values for sea level?
15 C (59 F) and 29.92”Hg (1013.2 mb)
What are isobars?
Line on a weather chart that connects areas of equal or constant barometric pressure
If the isobars are relatively close together on a surface weather chart or a constant pressure chart, what information will this provide?
Steep pressure gradient exists, higher winds. Shallow gradient will indicate lower wind speeds
What does dew point mean?
Temperature to which air must be cooled to attain saturation
How does fog form?
When the temperature and dewpoint become identical or nearly so. Can be achieved by either cooling or adding moisture thereby elevating the dew point
What factor primarily determines the type and vertical extent of clouds?
Stability of the atmosphere
Explain the difference between a stable atmosphere and an unstable atmosphere. Why is the stability of the atmosphere important?
Stability depends on the atmosphere’s ability to resist vertical motion. Unstable atmosphere leads. to larger vertical air movement thereby producing turbulent airflow and convective activity
How can you determine the stability of the atmosphere?
Temperature decreases uniformly and rapidly as you climb (nearly 3 C per 1,000) indicates unstable air whereas little to no change would indicate stable air
List the effects of stable and unstable air on clouds, turbulence, precipitation, and visibility
Stable - stratiform, smooth, steady, fair to poor visibility
Unstable - cumuliform, rough, showery, good
State the general characteristics in regard to the flow air. around high-pressure and low-pressure system in the Northern Hemisphere
Low - inward, upward, and counterclock wise
High - outward, downward, and clockwise
If your route of flight takes you toward a low pressure system, in general what kind of weather can you expect? What if you were flying toward a high pressure system?
Low - cloudiness, precipitation, bad weather
High - clear and good weather
Describe the different types of fronts
Cold - cold, dense, stable air replaces a body of warmer air
Occluded - Fast moving cold front catches up with a slow moving warm front; cold front occlusion and warm front occlusion
Warm - Warm air mass flows over colder air mass
Stationary front - Forces of two air masses are relatively equal
What are the general characteristics of the weather a pilot would encounter when operating near a cold front? A warm front?
Cold - Towering cumulus or cumulonimbus; tornado possible; poor visibility, variable gusty winds, temp/dew point and barometric pressure drop rapidly
Warm - Stratiform clods, drizzle; low ceilings, and poor visibility; variable winds; rise in temp
Note: Weather associated depends on the moisture available, stability of the air, slope of front, speed of front, and upper wind flow
What is a trough?
An elongated area of relatively low atmospheric pressure; air unable to expand outward and cannot descend further due to the ground, therefore, is forced to move upward, therefore, is an area of rising air
What is a ridge?
Elongated area of high atmospheric pressure; descending air
What service does the FAA provide for pilots to obtain a weather briefing?
Flight Service by 1-800-WX-BRIEF or online
What are the two main categories of sources of weather data?
Federal government - FAA and National Weather Service (NWS) and is the only approved authority for sources of weather observations
Commercial weather information providers - repackage weather products based on NWS information and modify layout
Does the weather data provided by commercial and/or third-party vendors satisfy the preflight action required by 14 CFR 91.103?
May not qualify, consult with FSS if in doubt
What type of weather briefings are available from an FSS briefer?
Standard - Mass dissemination
Abbreviated - supplement mass disseminated data
Outlook - Departure time is 6 or more hours in advance; only for planning purposes only
Inflight - Update a preflight briefing
What pertinent information should a weather briefing include? 7-1-5
Adverse conditions
VFR not recommended
Synopsis
Current conditions
Enroute forecast
Destination forecast
Winds aloft
NOTAMs
ATC Delay
Any other route related information may be requested
What is a Flight Information Services - Broadcast (FIS-B)
Ground service provided thru the ADS-B (978 MHz UAT dat link) network to provide weather and aeronautical information
Can onboard datalink weather (FIS-B) be useful in navigating an aircraft safely around an area of thunderstorms?
No; weather data is not real-time information only recent conditions
What is ATIS?
Automatic Terminal Information Services - continuous broadcast of recorded non-control information in select high-activity terminal areas; updated hourly or special weather
What type of information is provided in an ATIS broadcast?
Latest weather, ceiling, visibility, temp, dew point, wind direction (magnetic) and velocity, altimeter, pertinent remarks, instrument approach and runway in use
While en route, how can a pilot obtain updated weather information?
FSS on 122.22 and appropriate RCO frequencies
ATIS, ASOS, or AWOS broadcasts along route of flight
ARTCC
Datalink weather
ATC (work permitting)