Chapter #5 Flashcards
(35 cards)
Ideal weather conditions for the formation of dew and frost
- Objects on surface colder than dew point
- when objects near the surface become colder than the frost-point temperature
Difference between hygroscopic nuclei and hydrophobic nuclei
- Hygroscopic = water seeking, condenses when RH less than 100%
- Hydrophobic = water-repelling, condenses when humidity above 100%
Difference between dry and wet haze
- Dry Haze = has aerosols that scatter sunlight, causes a decrease in visibility
- Wet haze = has aerosols that cause a condensation process when RH >75%, particles slightly larger than in dry haze
For you to see your breath, does it have to be below freezing?
No, condenses because when it mixes with the air, it becomes super-saturated.
Four methods of fog formation
1) Cool the air to saturation
2) Add moisture to the air
3) Add moisture to colder air and mix to saturation
4) Mix two unsaturated air parcels to create a saturated air parcel
Five types of fog
1) Radiation
2) Advection
3) Upslope
4) Evaporation - Steam & Frontal
5) Ice
Process of formation/characteristics of Radiation Fog
Process of formation: Lowering the air temperature to the dew-point temperature
Characteristics:
- Usually overnight when skies are clear and wind is light
- Shallow, low-lying, most commonly found around sunrise
Process of formation/characteristics of Advection Fog
Process of formation: lowering the air temperature to the dew-point temperature
- occurs when warm, moist air moves over a colder surface, causes saturation to occur and therefore fog
Characteristics:
-Dense, widespread, long-lasting
Process of formation of Upslope Fog
Process of Formation: lower the air temperature to dew point temperature, when moist air rises over an elevated terrain, causes air to cool due to expansion
Difference between Steam Fog and Advection Fog
Steam Fog: forms when cold air is over a body of warmer water
Advection Fog: Formed when moist, warm air moves over a cold surface
Characteristics of Frontal Fog
Fog that forms when warm rain drops fall into an unsaturated layer of colder air near the surface
Characteristics of Cirrus
Thin, wispy clouds, made up of ice crystals that can be blown by upper levels winds into long streamers
Characteristics of Cirrostratus
High, thin, layered, ice crystals, may cover a large portion of the sky, can produce halos and/or sun dogs
Characteristics of Cirrocumulus
Small individual elements, Nickname is ‘Mackerel Sky’
Characteristics of Altostratus
Mid-level, gray to blue gray cloud composed of ice crystals and/or water droplets, sun or moon maybe dimly visible as a round disk
Characteristics of Altocumulus
Mid-level, ice crystals and/or water droplets, rounded individual puffy elements
Characteristics of Stratus
Grayish, low, layered, cloud that often covers the entire sky with uniform bases, could produce drizzle
Characteristics of Stratocumulus
Low cloud, puffy elements but shallow, may produce a brief snow shower during the winter season
Characteristics of Nimbostratus
Light to moderate steady rain or snow, no lightning is present
Characteristics of Cumulus
Puffy, cotton ball looking, water droplets, often seen on a warm summer afternoon
Characteristics of Cumulus Congestus
Good vertical growth, may have showery activity but lightning not yet present
Characteristics of Cumulonimbus
Scientific name for a thunderstorm, moderate to heavy rain, possible hail, and lightning
Difference between nimbostratus and cumulonimbus
Nimbostratus = light to moderate precipitation
Cumulonimbus = moderate to heavy precipitation accompanied by lightning
Clear: sky conditions (% and x/8?)
Clear below 24,000’ AGL (ASOS)
