Saturation and Adiabatic Processes in Meteorology

Condensation

Conversion of water vapor to water, resulting in a release of latent heat and is a warming process.

Saturation

Occurs when cooler air can hold less water vapor; if the air is cooled enough, it can become saturated.

Air mass mixing

Occurs when two air masses with different temperature and humidity contents converge and mix.

Cooling of the air (without vertical motion)

Many fogs are formed by the cooling of air without vertical motion.

Radiation fog

A low level cloud formed when the atmosphere loses heat through radiation loss.

Advection fog

Fog formed when warm, moist air is blown over a cool surface and chilled below the dew point temperature.

Upslope fog

Forms when humid air is forced up a slope.

Steam fog

Occurs when relatively cold, dry air moves over a warmer water surface, absorbing heat and evaporating moisture from the water surface.

Frontal fog

Associated with weather fronts, particularly warm fronts.

Cooling with the vertical motion of air

When air rises, it cools through expansion; when air sinks, it warms through compression.

Adiabatic process

The process in which a rising parcel of air cools through expansion and a sinking parcel warms through compression.

Dry Adiabatic Lapse Rate (DALR)

The rate at which an unsaturated parcel of air cools or warms, defined as DALR = 10° C/1000 m.

Saturated Adiabatic Lapse Rate (SALR)

The rate at which a saturated parcel of air cools, defined as SALR = 6° C/1000 m (variable).

Stability

Determined by comparing the temperature of an air parcel to that of its surroundings.

Forced (mechanical) convection

Includes processes such as orographic lifting, frontal lifting, and convergence.

Thermal (free) convection

Occurs due to heating of the surface by the sun or cold air over a warm surface.

Fog types

Includes upslope fog, steam fog, and frontal fog.

Cooling without vertical motion

A process that leads to the formation of fog, such as radiation fog and advection fog.

Lapse Rates

Refers to the rate at which temperature decreases with an increase in altitude.

Air parcel

A volume of air that can be analyzed for its temperature and humidity characteristics.

Latent heat

The heat released or absorbed during a phase change of water, such as condensation.

Convergence

The process where air flows together from different directions, leading to rising air.

Orographic lifting

Occurs when an air mass is forced to rise over a mountain range.

Frontal lifting

Occurs when a warm air mass is forced to rise over a cooler air mass.