Definitions
Air with a relative humidity greater than 100%.
What is supersaturated?
Homogeneous nucleation is very unlikely because of the
What is the Kelvin (curvature) effect?
This hypothesis describes why aerosols can increase cloud albedo (brighter clouds)
What is the Twomey hypothesis?
The growth of cloud droplets is dominated by vapor deposition and...
What is collision-coalescence?
Defined as a (visible) suspension of small water droplets or ice crystals in the atmosphere
What is a cloud?
This term describes the change in saturation vapor pressure due to a curved liquid-vapor interface
What is the Kelvin (curvature) effect?
Radiation, uplift, and mixing describe how this term can be achieved.
What is supersaturation?
Once a cloud drop starts to fall, then the air resistance forms another force called
What is drag?
Involves ice crystals growing at the expense of supercooled water droplets in mixed-phase clouds
What is the Bergeron process?
For the drop to be in equilibrium with the environment, the condensation rate of atmospheric water vapor must be ___ the drop's evaporation rate.
What is equal to?
The chemical that is being dissolved in the solvent
What is the solute?
This term is greater than 1 when the environment is supersaturated.
What is the Saturation Ratio?
Relates the equilibrium vapor pressure of the solution to that of pure water and to the mole fraction
What is Raoult's Law?
Lightning formation in clouds is hypothesized to be driven by
The saturation vapor pressure over a curved surface is __ the saturation vapor pressure over a flat surface of pure water
What is greater than?
Drops that reach this radius can activate and grow into a cloud drop
What is the critical radius?
As drops get bigger, their radius increases, and saturation vapor pressure over a curved surface approaches ___
What is the saturation vapor pressure (over a flat surface)?
This hypothesis describes why smaller droplets will reduce the efficiency of collision-coalescence
What is the Albrecht hypothesis?
This is believed to be initiated by a local discharge at a cloud base
What is a stepped leader (i.e., discharge)?
This process is responsible for local evaporation and reduced cloud liquid water content in growing convection
What is entrainment (of dry air)?
Describes a process by which a falling snowflake scavenges other snowflakes
What is aggregation?
The net inward force, divided by the distance along the surface, is called
What is surface tension?
This term in Raoult's Law accounts for the splitting of some solutes into components when they dissolve
What is the Van’t Hoff factor?
The fraction of the actual cross-sectional area that is swept out compared to the cross-sectional area that is geometrically possible
What is collision–coalescence efficiency?
These two effects most strongly determine the amount of supersaturation that each particle must experience in order to accumulate enough water to grow into a cloud drop
What are the physical (Kelvin) and chemical/solute (Raoult) effects?