Meteorology and Atmospheric Properties Flashcards

These vocabulary flashcards cover atmospheric properties, meteorological measurements, weather systems (cyclones, fronts), severe weather (thunderstorms, tornadoes, hurricanes), and environmental hazards (floods, droughts, heat waves) based on the lecture transcript.

Temperature

A measure of the average speed that molecules move in a substance.

Tropopause

The boundary between the troposphere and stratosphere that prevents vertical motions from moving into the stratosphere.

Atmospheric Pressure

The force applied by air on a unit area of surface.

Millibar (mb)

The unit of pressure used by meteorologists, with average sea level pressure being $1013.25\,mb$.

Relative Humidity

The amount of water vapor in the atmosphere relative to its capacity for moisture at a given temperature.

Dewpoint Temperature

The lowest temperature to which air can be cooled at constant pressure before saturation occurs.

Latent Heat

The “hidden heat” required for a phase change.

Synoptic Measurements

Meteorological measurements that are made simultaneously, coordinated using Universal Coordinated Time (UTC).

Rawinsonde

A balloon-borne instrument package used to measure atmospheric conditions above the surface, including pressure, temperature, dewpoint, and wind.

Doppler Radar

A radar system that measures the frequency shift of returned energy to determine the wind along the beam in addition to precipitation intensity.

Isobars

Lines of constant pressure on a weather map.

Isotherms

Lines of constant temperature on a weather map.

Isodrosotherms

Lines of constant dewpoint temperature on a weather map.

Numerical Weather Prediction (NWP)

The science of predicting future weather using mathematical models based on physical principles solved on a computer.

Ensemble Forecasting

A technique where a model is run repeatedly for the same case with slight changes to the initial state or model formulation to account for uncertainty.

Adiabatic Process

A process in which a parcel of air does not mix with or exchange heat energy with its environment.

Dry Adiabatic Lapse Rate

The rate at which an unsaturated air parcel cools as it rises, valued at $10\,^{\circ}C/km$.

Moist Adiabatic Lapse Rate

The rate at which a saturated air parcel cools as it rises, approximately $6\,^{\circ}C/km$ in the lower atmosphere.

Lifting Condensation Level (LCL)

The altitude where condensation first occurs (cloud base) when an air parcel is lifted from the surface.

Level of Free Convection (LFC)

The altitude where a rising air parcel becomes buoyant and warmer than its environment.

Coriolis Force

An apparent force associated with the rotation of the earth that acts to the right of the direction of motion in the Northern Hemisphere.

Geostrophic Balance

The force balance existing when the horizontal pressure gradient force is equal and opposite to the Coriolis force.

Hydrostatic Balance

The force balance existing when the vertical pressure gradient force is equal and opposite to the gravitational force.

Jetstreak

A region of exceptionally strong winds embedded within a jetstream.

Airmass

A large body of air (typically over one million square km) with relatively homogeneous surface characteristics, such as temperature and moisture.

Front

A boundary between two different airmasses.

Trowal

Acronym for “trough of warm air aloft”; a wedge of warm air that wraps around a low-pressure center to its North, Northwest, and West.

Nor’easter

A strong frontal cyclone offshore of New England that brings strong northeasterly winds and heavy precipitation.

Supercooled Water

Water that remains in a liquid state even though its temperature is below $0\,^{\circ}C$ ($32\,^{\circ}F$).

Ice Pellets

Frozen raindrops that reach the ground already in a solid state.

Wind Chill Temperature

The equivalent temperature felt by human skin due to heat loss caused by the combined effects of cold and wind.

Chinook Winds

Downslope windstorms on the east slope of the Rocky Mountains characterized by adiabatic warming during descent.

Mesoscale Convective System (MCS)

A large complex of thunderstorms, typically $200$ to $300\,miles$ in diameter, that provides critical summer rainfall to the Central Plains.

Supercell

A large, long-lived, rotating thunderstorm with organized updraft and downdraft circulations.

Mesocyclone

A cyclonic circulation within the updraft region of a supercell thunderstorm, normally where tornadoes form.

Enhanced Fujita (EF) Scale

A scale used to assign a rating to a tornado based on the extent of damage using Damage Indicators to estimate wind speeds.

Hail Embryo

A small ice particle that forms the core of a hailstone.

Interface Charging

The transfer of electrical charges between substances with different surface properties, such as graupel and ice crystals.

Downburst

A strong downdraft that originates within a cumulus cloud or thunderstorm and creates strong straight-line winds upon reaching the ground.

Microburst

A small (less than $4\,km$), intense downburst.

Virga

Rain that falls from a cloud base but evaporates before reaching the ground.

Saffir-Simpson Scale

The scale used to classify the intensity of hurricanes based on maximum sustained wind speed.

Watershed

The specific area of land that is drained by a particular stream or river.

Pineapple Express

An atmospheric circulation pattern that transports large amounts of tropical moisture from Hawaii toward the West Coast of North America.

Bermuda High

A semi-permanent surface high-pressure center over the North Atlantic that can influence drought conditions along the U.S. East Coast.

Urban Heat Island Effect

The phenomenon where urban areas are warmer than surrounding rural areas due to human activities and heat retention by structures.

Heat Index

A measure of the combined effect of high air temperature and relative humidity on the human body.