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.
parcel"An imaginary volume of fluid to which may be assigned various thermodynamic and kinematic quantities. The size of a parcel is arbitrary but is generally much smaller than the characteristic scale of variability of its environment.
Parcel
A volume of air small enough to contain uniform distribution of its meteorological properties and large enough to remain relatively self-contained and respond to all meteorological processes.
Parhelion ...
Parcels of air
A parcel of air is, in essence, nothing more than a sample of air. Generally it is assumed to be small enough to be homogenous (the same all the way through).
Parcel - permalink - collapse
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A volume of air small enough to contain uniform distribution of its meteorological properties and large enough to remain relatively self-contained and respond to all meteorological processes.
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 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 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- An imaginary small body of air that is used to explain the behavior of air.
Max Parcel Level (MPL) This signifies the highest attainable level that a convective updraft can reach; therefore, it is a good indication of how tall a thunderstorm may reach.
An air parcel initially at rest will move from high pressure to low pressure because of the pressure gradient force (PGF).
The temperature a parcel of dry air would have if brought adiabatically (i.e., without transfer of heat or mass) to a standard pressure level of 1000 mb.
PPI ...
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.
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.
Lifting Condensation Level - the level at which a parcel of moist air becomes saturated when it is lifted dry adiabatically.LDSLightning Detection SystemLDTLocal Daylight Time.
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.
adiabatic lapse rateThe rate of decreased temperature experienced by a parcel of air when it is lifted in the atmosphere under the restriction that it cannot exchange heat with its environment.
Air density The mass density of a parcel of air expressed in units of mass per volume. Airlight formula See Koschmieder's law.
Cap or Cap Strength: It measures the ability of stable air aloft (a layer of relatively warm air) to inhibit low-level parcel ascent.
It can be used to track air-parcel movement and to identify the origins of air masses. Examples are absolute humidity, equivalent potential temperature, radioactivity, and CCN composition. 2.
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.
stable and unstable atmospheric conditions: If a parcel of air is moved upward due to local convergence, convection, orographic lifting, ...
Such ascent/descent is said to be adiabatic, which means that the energy/heat changes are confined to that particular parcel.
Provided the parcel is warmer (less dense) than the environmental air through which it is passing, it is buoyant, and rises.
Specifically, it represents the cumulative effect of atmospheric layers they are warmer than the parcel moving vertically along the adiabat. Low level parcel ascent is often inhibited by such stable layers near the surface.
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.
VORTICITY The measurement of the rotation of a small air parcel. It has vorticity when the parcel spins as it moves along its path.
Baroclinic instability is a situation that results from the tight thermal gradients when air parcels are unstable to slantwise forcing.
INSTABILITY The state of equilibrium in which a parcel of air when displaced has a tendency to move further away from its original position. It is the condition of the atmosphere when spontaneous convection and severe weather can occur.
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.
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, ...
EQUILLIBRIUM LEVEL - The point in the atmosphere when a rising air parcel is the same temperature as the surrounding air. The parcel, in theory, will lose its buoyancy and stop rising at this level.
Atmospheric Stability - An indication of how easily a parcel of air is lifted. If the air is very stable it is difficult to make the parcel rise. If the air is very unstable the parcel may rise on its own once started.
stability: a state of the atmosphere when a parcel of air will return to its starting position when moved up or down. This is because the parcel of air is denser than its surrounding air. Stability is often associated with fair weather.
Atmospheric stability Property of ambient air that either enhances (unstable) or suppresses (stable) vertical motion of air parcels; ...
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 ...
DEWPOINT TEMPERATURE: The temperature to which a given parcel of air must be cooled at constant pressure and constant water vapor content in order for saturation to occur. Any further cooling usually results in the formation of dew or frost.
Specific humidity The ratio of the mass of water vapor in a given parcel to the total mass of air in the parcel.
Spontaneous nucleation (freezing) The freezing of pure water without the benefit of any nuclei.
Dew point (dew-point temperature) The temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur.
Adiabatic cooling takes place when a parcel of air moves upwards through the atmosphere. E.g. being forced over a mountain and adiabatic heating occurs when air descends as can happen in an area of high pressure ...
Conditionally Unstable-Atmosphere that is stable with respect to an unsaturated parcel of air, but unstable with respect to a saturated parcel of air.
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, ...
Adiabatic lapse rate - how quickly the temperature of a moving parcel of air changes, even though no heat enters or leaves it.
Gravity wave - A wave disturbance in which buoyancy acts as a restoring force on parcels displaced from hydrostatic equilibrium.
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.
The more unstable the parcel of air the more likely it will continue to rise with the possibility of severe weather. The more stable the air is indicates that the air will rise slowly or not at all.
 See also: Air, Temperature, Pressure, Water, Surface
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