Exam 3 Flashcards
Adiabatic Processes
No exchange of heat across the boundary of the parcel, associated with rising air.
Diabatic Processes
Assumes an exchange of heat between parcel and environmental air. Parcel sinking
DALR
The rate at which the temperature of unsaturated air changes as it ascends or descends in the atmosphere. Usually about 5 deg. F per 1000 ft.
ELR
Environmental Lapse Rates
When ELR > 5.5 F per 1000ft the atmosphere is
Absolutely Unstable
MALR
Moist Adiabatic Lapse Rate ~ 3.3 F per 1000 ft.
When ELR > MALR but ELR < DALR the atmosphere is
Conditionally unstable
When ELR < MALR the atmosphere is
Absolutely stable
Thermodynamic Diagram
Shows temperature and humidity with height
Stability is Enhanced by
Radiational cooling of the Earth after sunset
Cooling of air masses from below as they moves over colder surfaces.
Sinking air, or subsidence
High Clouds (20,000 ft.)
Cirrus, Cirrocumulus, Cirrostratus
Cirrus (Ci)
Wispy johns
Cirrocumulus (Cc)
Little cum puffs, indicative of instability in upper air
Cirrostratus (Cs)
Super thin wide layer clouds at high levels
Middle Clouds (6,000-20,000ft)
Altocumulus, Altostratus
Altocumulus (Ac)
Grey and white thumb-puff size with dark bases, indicates middle air instability
Altostratus (As)
Very large cloud covering the entire sky, usually makes the sun look like a glowing disk. Form in advance of storms that produce widespread precip
Low Clouds (Surface - 6000ft)
Stratus, Stratocumulus, Nimbostratus
Stratus
Low clouds 2000 ft up, drizzle
Stratocumulus
Low and lumpy, form when cumulus break up
Nimbostratus
Big grey lumpy clouds, no thunder, medium precip
Cumulus
Big dumpers, indicate rising air motion, instability.
Undulatus
Waves, associated with Altocumulus
Translucidus
TO shine through, Cirrostratus
