An air parcel is a meteorologically defined chunk of air in the atmosphere. Meteorologists study the movements and changes in air parcels over time as one tool in weather forecasting.
air parcel"An imaginary volume of air to which may be assigned any or all of the basic dynamic and thermodynamic properties of atmospheric air.
air parcel—See parcel.
albedo—The ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it, commonly expressed in percentage; in meteorology, ...
Air Parcel - an imaginary body of air a few meters in diameter which possesses nearly uniform properties within it
Air Pollution - airborne gaseous, chemical, or organic matter which pollutes the atmosphere ...
Air parcel See Parcel of air.
Air pollutants Solid, liquid, or gaseous airborne substances that occur in concentrations high enough to threaten the health of people and animals, to harm vegetation and structures, ...
Air Parcel- An imaginary small body of air that is used to explain the behavior of air.
Moving Air Parcel:
This animation depicts how the pressure gradient and Coriolis forces influence the movement of air parcels.
coriolis force ...
However, air parcels displaced along certain sloped, or "slantwise" trajectories may attain positive buoyancy due to a unique combination of gravitational and centrifugal forces.
When a dry air parcel is lifted adiabatically, its pressure falls, and so it expands. This expansion takes place against the inwards pressure of the surrounding environmental air on the parcel.
The path of an air parcel that flows steadily over or around an obstacle.
STRFM
Stratiform ...
The tendency for air parcels to accelerate when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted.
It is determined by lifting an air parcel to 500 millibars and then comparing its temperature to that of the environment. If the parcel is colder than its new environment, then the atmosphere is more stable.
They are obtained on a sounding by computing the area enclosed between the environmental temperature profile and the path of a rising air parcel, over the layer within which the latter is cooler than the former.
Instability(abbrev. INSTBY)- The tendency for air parcels to accelerate when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted.
Theta-e, which typically is expressed in degrees Kelvin, is directly related to the amount of heat present in an air parcel. Thus, it is useful in diagnosing atmospheric instability. Theta-e RidgeAn axis of relatively high values of theta-e.
an air parcel) and its surroundings. In an adiabatic process, compression always results in warming, and expansion results in cooling.
Mixing RatioThe ratio of the weight of water vapor in a specified volume (such as an air parcel) to the weight of dry air in that same volume.
Equilibrium Level(EL) - On a sounding, the level above the level of free convection (LFC) at which the temperature of a rising air parcel again equals the temperature of the environment.
Air parcels rising into this layer become cooler than the surrounding air, which inhibits their ability to rise further. As such, the cap often prevents or delays thunderstorm development even in the presence of extreme instability.
Any instrument used to measure the water vapor content of an air parcel (atmospheric humidity) by evaporative cooling of the air to its wet bulb temperature. Examples include a sling and an aspirated psychrometer.
in a slow moving anticyclone, or a tropical maritime airmass, then an air parcel subject to lifting/adiabatic cooling will readily find itself colder than its surroundings ... denser ...
VORTICITY The measurement of the rotation of a small air parcel. It has vorticity when the parcel spins as it moves along its path.
STABLE/STABILITY Occurs when a rising air parcel becomes denser than the surrounding air. It will then return to its original position.
Instability: The tendency for air parcels to accelerate their motion when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted by either topographical features, convergence, ...
CONDENSATION PRESSURE DEFICIT (COND PRES DEF)- On an isentropic chart (a layer of constant potential temperature), condensation pressure deficit represents the amount of lift, expressed in millibars, needed to saturate an air parcel.
Atmospheric stability Property of ambient air that either enhances (unstable) or suppresses (stable) vertical motion of air parcels; ...
FREE CONVECTION - Region where air in a rising air parcel is always warmer, and thus less dense, than the surrounding air. The air parcel will continue rising as long as it is lighter that the surrounding air.
A measure of the spin of a fluid, usually small air parcels. Absolute vorticity is the combined vorticity due to the earth's rotation and the vorticity due to the air's circulation relative to the earth.
CAP Composed of a layer of warmer, dryer air aloft which may suppress or delay the development of thunderstorms. As an air parcel rises, it becomes cooler relative to the ambient, or surrounding, air in the cap and therefore, ...
The rate of change of temperature in a rising or descending saturated air parcel. The rate of cooling or warming varies but a common value of 6C per 1000 m (3.3F/1000 ft) is used. "Molecular viscosity
Monsoons(3) ...
The rising air now cools and the moisture in that air parcel begins to condense into ice crystals and clouds form.
When enough moisture condenses out of the air, it falls in the form of snow over the water and the lee side (downwind side) of the lake.
EQUIVALENT POTENTIAL TEMPERATURE- The temperature of a parcel of air after all moisture and latent heat is condensed out of an air parcel then descended to the 1000 mb level. Also known as Theta-E ...
environmental lapse rate: the rate of decrease of air temperature as altitude increases. Is compared to the dry adiabatic lapse rate or moist adiabatic lapse rate to determine vertical motions of an air parcel.
enhanced static stability separating a layer below possessing large convective available potential energy from a layer above with lower static stability. The presence of a lid is generally accompanied by substantial convective inhibition. Air parcels ...
out, and
c) it was returned adiabatically (i.e., without transfer of heat or mass) to a pressure of 1000 millibars.
Theta-e, which typically is expressed in degrees Kelvin, is directly related to the amount of heat present in an air parcel.
Lifting condensation levelThe level in the atmosphere where a lifted air parcel reaches its saturation point, and as a result, the water vapor within condenses into water droplets.
Potential temperature Temperature assumed by an unsaturated air parcel when brought adiabatically to a standard pressure (1,000 mb). Potentiometer An instrument for measuring differences in electric potential.
 See also: Parcel, Air, Temperature, Atmosphere, Pressure
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