Weather Flashcards by Ryan Fischer

Define: Trough

An area of low pressure.

Area of rising air. Rising air is conducive to cloudiness and precipitation. (bad weather with low pressure)

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Define: Ridge

An area of high pressure.

Area of descending air. This favors dissipation of clouds. (good weather with high pressure)

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Define: Isobars

Connects areas of equal pressure

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What does it mean when isobars are close together?

There is a steep pressure gradient and higher wind speeds exist.

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

The Coriolis Force

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

Surface friction

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Define: Dew Point

The temperature at which the air must be cooled to become saturated

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Dew point and temperature close together means what?

Clouds, fog, dew

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How do you determine stability of the atmosphere?

Unstable: temperature decreases uniformy and rapidly 3 degrees celcius every 1000ft
Stable: temperature remains unchanged or decreases slightly with altitude

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During pre-flight, what type of meteorological information should you be aware of with respect to icing?

Location of fronts
Cloud layers
Freezing levels
Air temperature and pressure

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Define: Freezing Level

Lowest altitude in the atmosphere at which the air temperature is 0 degrees celcius.

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Where can you get icing information?

PIREPs
AIRMETs
SIGMETs
Area Forecasts

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What conditions are necessary for structural icing?

Visible moisture

Below freezing temperatures at the point moisture strikes the aircraft

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

Structural icing
Induction system icing
Instrument icing

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What are the 3 types of structural icing?

Clear ice
Rime ice
Mixed ice

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What action should you take if you encounter icing conditions?

Leave the area of visible moisture

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What factors must be present for a thunderstorm?

Sufficient water vapor
Unstable lapse rate
Lifting force

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What are the 2 ways fog can form?

Cooling air to the dewpoint

Adding moisture to the air near the ground

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5 types of fog

Radiation fog
Advection fog
Upslope fog
Precipitation induced fog
Ice fog

Define: Wind Shear

Big change in wind velocity and direction
Can occur:
 -low level temperature inversion
 -frontal zone / thunderstorm
 -clear air turbulence

What types of weather reports will you use to determine if wind shear might exist?

Terminal forecasts
METARs
SIGMETs
LLWAS (low level wind shear alert system)
PIREPs

What is the primary means of obtaining a weather report?

FSS

1-800-WX-BRIEF

What types of weather briefings are available from FSS?

Standard briefing
Abbreviated briefing
Outlook briefing
In-flight briefing

Define: EFAS

En Route Flight Advisory Service

weather advisories in flight
PIREPs
122.0 “flight watch”

Define: HIWAS

Hazardous In flight Weather Advisory Service

Define: PIREPs

Pilot weather reports. UA - Standard Pilot Report UUA - Urgent Pilot Report

Define: Radar Weather Report (SD)

Contains information on precipitation observed by weather radar

Define: Aviation Area Forecast (FA)

Used to determine en-route weather and to interpolate weather conditions at airports with not TAFs

What is the use of In-flight aviation weather advisories (WST, WS, WA)?

Warn of potentially hazardous weather - SIGMET - Convective SIGMET - AIRMET

Define: Convective SIGMET

``` Severe thunderstorm -50 knot surface winds -3/4" hail -tornadoes Embedded thunderstorms Line of thunderstorms ```

Define: SIGMET

Severe icing not associated with thunderstorms Severe turbulence or clear air turbulence Volcanic ash Dust or sand storms

Define: AIRMET Sierra

IFR conditions or mountain obstructions

Define: AIRMET Tango

Moderate turbulence 30 knot surface winds Wind shear

Define: AIRMET Zulu

Moderate icing | Freezing level heights

Why use Winds and Temperatures aloft?

Determine most favorable altitude Possible icing Temperature inversions Turbulence

Examples of weather charts available for flight planning?

``` Surface analysis charts Weather depiction chart Radar summary chart Short range surface prog chart Significant weather prog chart Convective outlook chart Constant pressure analysis chart ```

Define: Surface Analysis Chart

Pressure systems and fronts Winds, temperatures, dew point temperatures - transmitted every 3 hours

Define: Low IFR

Ceiling less than 500 ft | Visibility less than 1 mile

Define: IFR

Ceiling 1000-500 ft | Visibility 1-3 miles

Define: Marginal VFR (MVFR)

Ceiling 1000-3000 ft | Visibility 3-5 miles

Define: VFR

Ceiling greater than 3000 ft | Visibility 5+ miles

Define: Radar Summary Chart

Shows areas of precipitation | -general areas of movement of precipitation and storms

Define: Short Range Surface Prognostic Chart

"progs" surface up to 24,000 ft forecast weather conditions (12, 24, 36, 48 hr progs)

Define: Low Level Significant Weather Prog Chart

Forecast significant weather from surface to FL240 - 2 lower panels depict 12 & 24 hour surface progs - 2 upper panels depict 12 & 24 hour sig weather progs

Define: Mid-Level Significant Weather Chart

Forecast and overview of significant en-route weather from 10,000 to FL450 -4 times daily

Define: Convective Outlook Chart

Depicts area forecasts to have the potential for severe and non-severe weather threats (every 3 days)