PPL - Weather Patterns
Terms
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- What is Adiabatic Heating and Adiabatic Cooling ?
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Adiabatic Heating is when air descends it's pressure increases, volume decreases, and temp. increases.
Adiabatic Cooling is when air rises, pressure decreases, volume increases, and temperature decreases. - What is Temperature Inversion and when does it occur ?
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-It is when temp. increases with alt.
-It occurs in stable air with little or no wind and turbulence. - What is Evaporation ?
- It is when iquid water changes to invisible water vapor.
- What is Condensation ?
- It is when water vapor changes to a liquid, as when water drops form on a cool glass on a warm day.
- What is Sublimation ?
- It is when ice change into water vapor.
- What is Deposition ?
- It is when water vapor turns into ice.
- What is Humidity and Relatvie Humidity ?
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- Humidity simply refers to moisture in the air.
- Relative Humidity is the actual amount of moisture in the air compared to the total amount that could be present at that temperature. - When is air said to be saturated ?
- When the dewpoint has been reached, as in when the air contains 100% of the moisture it can hold at that temp.
- How do clouds form and how can you anticipate the formation of fog or cloud ?
- As air cools to its saturation point, condensation changes invisible water vapor into clouds. By monitoring the differences between surface temp. and dewpoint. AKA temerpature/dewpoint spread.
- What is the dry adiabatic lapse rate (unsaturated air) and the moist adiabatic lapse rate ?
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- 3 degree celsius
(5.4 degree fahreneit)/ 1000 FT
- varies from 1.1 C to 2.8 degree C (2F - 5F)/1000 FT - Explain Atmospheric Stability ?
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- In a stable enviroment, vertical airflow motions are smooth and small.
- In an unstable atmosphere, air rises because it is warmer than its surroundings (convection). This instability can lead to severe cloud development, turbulence, and hazardous weather. - How can air be cooled ?
- By moving over a cooler surface, rising, or cooled from the underlying surface.
- What do Stratus, Cumulus, Cirrus, and Nimbus all refer to ?
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stratus > sheet-like clouds
Cumulus > puffy clouds
Cirrus > wispy clouds
Nimbus > violent rain - What are Low Cloud characteristics ?
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- Low clouds extend from near the sfc. to about 6500 FT AGL.
- Consist of water, or supercooled water which can create an icing hazard for aircraft.
- Types include: stratus, stratocumulus, & nimbostratus - What are Middle Cloud characteristics ?
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- Middle clouds have base ranage from about 6500-20000 FT AGL.
- Consist of water, ice crystals, or supercooled water, and may contain moderate turbulence and potentially severe icing.
- Types include: Altostratus and Altocumulus. - What are High Cloud characteristics ?
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- High clouds have bases beginning above 20000 FT AGL.
- white to light gray in color and form in stable air.
- Consist of ice crystals and seldom pose a serious turbulence or icing hazard.
- Types include: Cirrus, Cirrostratus, & Cirrocumulus - The lifting of unstable air can cause...... ?
- Vertical cloud development and turbulence.
- What is an Airmass ?
- is a large body of air with fairly uniform temp. and moisture content.
- Describe the tropical airmass source regions ?
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- from the south of west and east there is the
Martime Tropical (mT) [Warm,Moist]
- in the south is the
Continental Tropical (cT)
[Hot,Dry] - Describe the polar airmass source regions ?
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- from the north of west and east there is the
Maritime Polar (mP)
[Cool,Moist]
- in the north is the
Continental Polar (cP)
[Cool,Dry] - What is a Front and wat is a Cold Front, Warm Front, Stationary Front, and Occluded front ?
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Front: a boundary between airmasses
Cold front: cold air is moving to displace warmer air
Warm front: warm air is moving to displace colder air
Stationary front: has no movement
Occluded front: is when cold and warm fronts merge. - What is Frontal discontinuities and it's 3 types ?
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- It is the rapid changes in the meteorological characteristics of an airmass
- Temperature, Wind, Pressure - What causes Radiation Fog ?
- - moist air over low, flat areas on clear, calm nights.
- What causes Advection Fog ?
- - when a low layer, of warm , moist air moves over a cooler surface.
- What causes Upslope Fog ?
- - when moist, stable air is forced up a sloping land mass.
- What causes Steam Fog ?
- - when cold, dry air moves over comparatively warmer water.
- Stratocumulus Clouds characteristics ?
- - are white puffy clouds that form as stable air is lifted.
- Nimbostratus cloud characteristics ?
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- are gray or black clouds
- can be more than several thousand feet thick
- contain large amount of moisture
- produces widespread areas of rain or snow
- if temp. is below freezing, they may create heavy aircraft icing.