EAS 1310

Adiabatic Cooling

Cooling caused by the expansion of a rising air parcel as it moves into lower atmospheric pressure, without exchanging heat with its surroundings.

Adiabatic Lapse Rate

The rate at which an air parcel changes temperature as it rises or sinks without exchanging heat with its surroundings.

Adiabatic Process

A process in which an air parcel changes temperature without exchanging heat with its surroundings.

Adiabatic Warming

Warming caused by compression as an air parcel descends into higher atmospheric pressure.

Cloud Base

The lowest level of a cloud; in the parcel model, approximately the level where rising air first becomes saturated and condensation begins.

Composition

The mixture of gases making up the atmosphere. Composition affects density because different atmospheric molecules have different masses.

Convection

Vertical atmospheric motion driven primarily by buoyancy.

Diabatic Process

A process in which energy is transferred between an air parcel and something outside the parcel.

Examples include heating by a fire, the ground, or radiation.

Dry Convection

Buoyancy-driven vertical motion that occurs without saturation or cloud formation.

Dry-Adiabatic Lapse Rate

The rate at which an unsaturated air parcel changes temperature as it rises or sinks adiabatically.

For rising dry air, the temperature decreases by approximately 9.8°C per kilometer.

Environmental Lapse Rate

The observed rate at which atmospheric temperature changes with height at a particular place and time.

Latent Heat

Energy associated with a change of phase.

In moist convection, condensation transfers energy to the surrounding air-cloud system and helps offset some of the cooling caused by expansion.

Lapse Rate

The rate at which temperature changes with height.

Moist Convection

Buoyancy-driven vertical motion in which water vapor eventually condenses and commonly produces clouds.

Moist-Adiabatic Lapse Rate

The rate at which saturated rising air cools during adiabatic ascent.

It is smaller than the dry-adiabatic lapse rate because condensation releases latent heat.

Potential Temperature

The temperature an air parcel would have if it were brought adiabatically to a standard reference pressure, usually 1000 hPa.

Potential temperature purpose

allows air at different pressure levels to be compared on a common basis.

Power

energy divided by time.

Pyrocumulus

A cumulus cloud produced or enhanced by intense surface heating, commonly from a fire.

Specific Gas Constant

A constant used in forms of the ideal gas law that apply to a specific gas.

For dry air it is commonly written as Rd.

Thermal

A rising region or plume of relatively warm, buoyant air produced by surface heating.

Unsaturated Air

Air containing less water vapor than is required for saturation at its current temperature and pressure.

Virtual Temperature

The temperature dry air would need to have to possess the same density as moist air at the same pressure.

Virt temp purpose

provides a way to account for the effect of water vapor on air density.

Water vapor does whar?

affects atmospheric density and provides latent heat when it condenses.