Exam 1- definitions and concepts Flashcards
Adiabatic
If a material undergoes a change in its physical state (e.g. its pressure, volume, or temperature) without any heat being added to it or withdrawn from it
Aerosols
Tiny solid or liquid suspended particles of various composition
Outgassing
The constant outpouring of gases from earth’s hot interior
Lapse rate
The rate at which the air temperature decreases with height. Environmental lapse rate is around 6.5 deg C/km
Temperature inversion
When air temperature increases with height.
Definition of climate
The accumulation of daily and seasonal rather events over a long period of time.
Concept of an air parcel
1) Thermally isolated from its environment
2) Always remaining at exactly the same pressure as its environment
3) Moving slowly enough that the macroscopic kinetic energy of the air parcel can be neglected.
First law of thermodynamics
= conservation of energy.
for atmosphere:
deltaEmechanical + delta E internal = 0
where delta E mechanical is parcel expansion/compression and delta E internal is work done to outside environment
P * delta V + delta E_internal = 0
conditionally unstable
when ELR is between DALR and SALR. Air parcel will become buoyant if lifted to the level of free convection.
stable with respect to unsaturated air, stable with respect to saturated air.
equation for first law of thermodynamics
PdV + CvdT = 0
dew point
temperature to which air must be cooled at constant pressure to become saturated with respect to a plane surface of pure water.
lifting condensation level
the level to which an unsaturated (but moist) parcel of air can be lifted adiabatically before it becomes saturated
equivalent potential temperature
air is lifted adiabatically until all of the vapor condenses, releases its latent heat, and falls out. the air is then compressed dry adiabatically to 1000 hPa. its temperature at this point is the equivalent potential temperature.
growth of cloud droplets, warm clouds
collision and coalescence
growth of cloud droplets, cold clouds
Bergeron process
Riming and Aggregation
nucleation
the deposition, freezing, or condensation of water vapor in the free air onto condensation nuclei.
Bergeron process
important in clouds with temperatures below freezing. Interactions between ice particles, supercooled water, and water vapor. “three-phase process” driven by the fact that the saturation vapor pressure over ice is less than that over supercooled water.
- ice crystals surrounded by many supercooled droplets
- water molecules evaporate from the droplets and deposit onto the ice crystal.
Riming
analogous to droplet collision
collision of ice crystals and supercooled water droplets. causes rapid growth of ice crystals and acceleration of their fall speeds
freezing rain
light rain or drizzle of supercooled water droplets fall through the air at or slightly below 0 deg C. It freezes when it hits the ground.
sleet
raindrops freeze to tiny transparent ice or ice pellets while still in the air.
graupel
liquid drops freeze onto the surface of ice crystals, and the shape of the original crystal is no longer identifiable.
precip from nimbostratus:
steady precip
precip from cumulonimbus
thunderstorms. showery precip
clouds with vertical development
cumulus, cumulonimbus
the wind direction is
the direction from which the wind is blowing
middle latitude storms are also known as
extratropical cyclones
dry air is _____ dense than humid air
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