stability quiz Flashcards
what is the dry adiabatic lapse rate (DALR)?
10ºC per 1000m
what is the saturated (moist) adiabatic lapse rate (SALR)?
~6ºC per 1000m
when unstable, warmer air than environment…
rises
when stable, colder air than environment…
sinks
what is the environmental lapse rate (ELR)?
observed temperature profile of atmosphere on any given day
what is an absolutely stable environment?
- ELR less than saturated lapse rate (ELR < SALR)
- usually cool, near surface air
- if an air parcel is forced to rise, it will spread horizontally and form stratus clouds
how are subsidence inversions formed?
when strong high pressure cells have sinking motions
strong subsidence traps air pollution due to what?
lack of vertical motion
what is a neutral atmosphere?
- ELR is the same as DALR or SALR
- rising air will always be the same as the environmental temperature
what is an absolutely unstable atmosphere?
- ELR greater than the DALR
- rising air is always warmer than surrounding air
- as air parcel rises, it forms a vertical cloud (which further enhances instability)
what atmosphere is best for convection, thunderstorms, and severe weather?
absolutely unstable atmosphere
what is a conditionally unstable atmosphere?
- ELR is between DALR and SALR
- ELR averages at 6.5ºC / km (atmosphere usually in this state)
what is a conditionally stable atmosphere?
- cool air aloft (radiational cooling, cold air advection)
- warming of surface (isolation, warm air advection)
- mixing and lifting
how do clouds develop?
an air parcel (saturates) rises and cools to the dew point temperature
what are the four triggers to initiate a rising air parcel?
- convection (warm air rises, vertical motion)
- orographic (topography)
- frontal (warm & cold, dry lines [density])
- convergence (air coming together)
