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18 Cards in this Set
- Front
- Back
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Trough vs Ridge |
Trough: elongated area of relative low pressure -> Rising air -> cloudiness & precipitation
Ridge: elongated area of relative high pressure -> Descending air -> Dissipation of cloudiness. |
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Isobars |
Lines of same barometric pressure |
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Factors required for thunderstorm formation |
3 factors: - Instability - Moisture - Lift
* hot temp not required. |
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Stages of thunderstorm |
- Cumulus: Updrafts - Mature: Begins when precipitation starts. Updrafts and downdrafts - Dissipating: Downrafts!
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Convective sigmets |
- Convective significant weather - Issued hourly - Lines of thunderstorms - Embedded and severe thunderstorms |
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SIGMET |
Potentially hazardous weather: - Severe icing - Severe or extreme turbulence - Duststorms - Sandstorms - Volcanic ashes |
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AIRMETS |
Specially useful for small and VFR: Sierra: - IFR Conditions - Mountain obscuration
- Moderate turbulence - Surface winds > 30kts - LLWS
Zulu: - Moderate icing - Freezing levels
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EFAS |
En route Flight Advisory Service: - provides weather info. Over 5000' AGL - 122.00 |
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Freezing level |
Lowest altitude over a given location at which the air temp reaches 0C. - There can be several (temp inversion above a freezing level). - Find in PIREP's, FA, AIRMET's, SIGMET's |
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Conditions necessary for STRUCTURAL ICING |
Visible moisture Below freezing temp at the point moisture strikes the aircraft |
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Main types of icing |
- Structural icing - Induction system icing - Instrument icing |
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Types of structural icing |
- Clear: forms after initial impact - Rime: small drops (stratified clouds, drizzle) - Mixed: when drops vary in size or liquid drops are interingled with snow. |
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What to do if encountering icing? |
- Get out of visible moisture
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Types of fog |
Radiation Advection Upslope Steam |
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Explain radiation fog |
On clear calm cool nights, the ground decreases it's temp due to radiation, cooling down moist warm air -> fog |
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Explain advection fog |
Result of movement of warm moist air over cold surface. Typical in coastal areas. Requires wind. |
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Explain upslope fog |
It forms when wind moves upslope a mass of moist stable air. |
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Wind-shear |
Change of wind speed/direction per unit distance. Usually found in: - Low level temperature inversion - Frontal zone or thunderstorm - Clear air turbulence at high levels associated with a jet stream
Dangerous: it will change the relative wind speed suddenly |
