Atoc Chapt 5 and 6 Flashcards

Ch5 – What is condensation?

The process by which water vapor changes into liquid water when air is saturated and cooled below its dew point.

Ch5 – What are condensation nuclei?

Microscopic particles such as dust, salt, or smoke on which water vapor condenses to form cloud droplets.

Ch5 – Why can’t water vapor easily condense on its own?

Because the curved surfaces of very small droplets make it hard for water molecules to stick; condensation nuclei reduce surface tension.

Ch5 – What are the main types of condensation at ground level?

Dew, frost, and fog.

Ch5 – What conditions lead to dew formation?

Clear, calm nights with surface cooling by radiation until the temperature drops to the dew point.

Ch5 – What causes frost to form?

When surface temperature falls below freezing and water vapor deposits directly as ice crystals.

Ch5 – What are the main types of fog?

Radiation fog, advection fog, upslope fog, and evaporation (steam) fog.

Ch5 – How does radiation fog form?

By nighttime cooling of the ground, cooling the air above to its dew point under clear skies and calm winds.

Ch5 – How does advection fog form?

When warm, moist air moves over a cooler surface and cools to its dew point.

Ch5 – How does upslope fog form?

When moist air flows upward along terrain and cools adiabatically to its dew point.

Ch5 – How does evaporation fog form?

When cold air moves over warm water, causing evaporation that saturates the lower air layer.

Ch5 – What determines the type of cloud that forms?

The altitude, stability of the air, and lifting mechanism (convection, frontal, orographic, convergence).

Ch5 – What are the 10 basic cloud types?

Cirrus, Cirrostratus, Cirrocumulus, Altostratus, Altocumulus, Stratus, Stratocumulus, Nimbostratus, Cumulus, Cumulonimbus.

Ch5 – What are high clouds composed of?

Ice crystals; include cirrus, cirrostratus, and cirrocumulus.

Ch5 – What are middle clouds composed of?

Mainly water droplets, sometimes ice; include altostratus and altocumulus.

Ch5 – What are low clouds composed of?

Mostly liquid water; include stratus, stratocumulus, and nimbostratus.

Ch5 – What clouds produce steady precipitation?

Nimbostratus clouds.

Ch5 – What clouds produce thunderstorms?

Cumulonimbus clouds.

Ch5 – What are lenticular clouds?

Lens-shaped clouds that form over mountains due to orographic lifting.

Ch5 – What are mammatus clouds?

Pouch-like structures hanging beneath cumulonimbus clouds; indicate turbulence.

Ch5 – What is fog most similar to?

A cloud resting at the ground.

Ch6 – What is atmospheric stability?

The tendency of air parcels to resist or enhance vertical motion depending on temperature differences with surrounding air.

Ch6 – What is an air parcel?

A small hypothetical bubble of air that moves independently from its surroundings for analysis of stability.

Ch6 – What is the dry adiabatic lapse rate (DALR)?

10°C per 1000 m; the rate at which unsaturated air cools as it rises or warms as it sinks.

Ch6 – What is the moist adiabatic lapse rate (MALR)?

About 6°C per 1000 m; slower cooling because condensation releases latent heat.

Ch6 – What is the environmental lapse rate (ELR)?

The actual rate of temperature decrease with height in the atmosphere at a given place and time.

Ch6 – How do you determine stability?

Compare the parcel’s lapse rate (DALR or MALR) to the environmental lapse rate.

Ch6 – When is the atmosphere absolutely stable?

When the environmental lapse rate is less than the moist adiabatic rate (ELR < MALR).

Ch6 – When is the atmosphere absolutely unstable?

When the environmental lapse rate is greater than the dry adiabatic rate (ELR > DALR).

Ch6 – When is the atmosphere conditionally unstable?

When the ELR is between the dry and moist adiabatic lapse rates (MALR < ELR < DALR).

Ch6 – What happens when air is stable?

Rising air cools faster than surroundings and sinks back down; clear skies, calm weather.

Ch6 – What happens when air is unstable?

Rising air remains warmer than surroundings and continues to rise; cumulus or cumulonimbus clouds form.

Ch6 – What is convection?

Vertical air movement caused by surface heating that creates buoyant rising thermals.

Ch6 – What are the four main lifting mechanisms?

Convection, orographic uplift, frontal lifting, and convergence.

Ch6 – What is orographic lifting?

Air forced to rise over a mountain range; causes cooling, cloud formation, and precipitation on the windward side.

Ch6 – What is frontal lifting?

Warm air forced to rise over cooler, denser air along fronts (cold, warm, or occluded).

Ch6 – What is convergence lifting?

When air flows toward a low-pressure center and rises where it meets.

Ch6 – What is conditional instability responsible for?

Cumulus development, thunderstorms, and deep convection under moist conditions.

Ch6 – How does surface heating affect stability?

Strong heating or cooling aloft makes air unstable; radiative cooling or subsidence aloft stabilizes it.

Ch6 – What is an inversion?

A layer in which temperature increases with height, producing strong stability and limiting vertical motion.

Ch6 – Why are mornings often more stable than afternoons?

Because surface air is cooler after overnight radiative cooling, reducing buoyancy.

Ch6 – Why are afternoons often unstable?

Because solar heating warms the surface and lowers the air density, promoting rising motion.