Atmosphere Exam 3

Radiative inversions (nocturnal inversions)

Inversions formed when the surface cools more rapidly than the air above. THese are most common on days without clouds and when winds are calm (no forced convection). Radiative inversions can be very shallow at 10s of meters in depth. They are disrupted when the sun rises;

Atmospheric boundary layer (ABL) inversions

defined by the height to which the surface atmosphere is mixed via daytime convection

marine layer inversions

cool air from over the ocean moves inland underneath warmer continental air

subsistence inversions

when air sinks from a higher altitude, which, as it does, it compresses, causing the temperature to increase

frontal inversions

when a cold air mass moves in underneath a warm air mass

environmental lapse rate

the decrease in temperature of air with altitude for a specific time and place

specific humidity (q_v)

the mass of water per unit moist air

virtual temperature

the temperature a dry parcel of air would need to have in order for that parcel’s density to equal the density of the moist parcel, assuming equal pressures

climate mitigation

policies and practices that reduce f

climate adaptation

policies and practices that respond to changes brought on by climate change

specific heat

the amount of energy needed to raise the temperature of 1g of a substance by 1^oC

first law of thermodynamics

the total energy of an isolated system is constant 0- energy can be transformed but not created or destroyed

joules law

if an ideal gas expands without doing external work and without exchanging heat, then the temperature doesn’t change

adiabatic process

no heat is exchanged

lifting condensation level (LCL)

the pressure at which saturation is achieved by a parcel ascending adiabatically

absolutely stable

when the environmental lapse rate is less than the moist adiabatic rate

absolutely unstable atmosphere

when the environmental lapse rate is greater than the dry adiabatic lapse ratec

conditionally unstable atmosphere

stable to dry adiabatic motions and unstable to moist adiabatic motions (typical in atmosphere)

sublimation

solid to gas

deposition

gas to solid

liquid-gas equilibrium

when the rate of condensation = rate of evaporation

saturation vapor pressure (e_s)

the amount of water in the gas phase at equilibrium

supersaturation

e > e_s → only exists when cooling occurs faster than condensation can occur

dew point

the temperature to which air needs to be cooled for saturation to occur for fixed e (vapor pressure of water)

latent heat of vaporization (L)

amount of energy needed to change the phase of water from a liquid to a gas

curvature effect

for very small droplets, the curved shape of droplets means more gas-phase water molecules fit above the surface and are required to maintain equilibrium. the smallest droplets require conditions of supersaturation just to maintain equilibrium, let along growth

radiation fog

think radiative inversion. fog that forms on calm, clear nights as the Earth radiationally cools

more common in the morning

can be opaque enough to prevent surface warming

advection fog

fog that forms as warm moist air moves over a cold surface. the surface must be cold enough to cool the air to its dew point. requires air movement and can occur during the day

upslope fog

fog that forms as moist air flows up a mountain side. the air cools as it is lifted

bergeron process

saturation vapor pressure of water higher above liquid water and ice

accretion

ice crystals sticking to supercooled liquid droplets

aggregation

ice crystals collide and fracture, function as seeds form more crystallization