Meteorology Topics
- Absolute Altitude
- Altitude above the actual surface, either land or water, of a planet or natural satellite.
- Absolute Temperature
- Temperature measured on a scale that sets absolute zero as zero.
- Adiabatic Saturation Process
- A process to determine absolute or relative humidity.
- Aerology
- The study of atmospheric conditions away from ground level.
- Aerometry
- The science of measuring the air, including the doctrine of its pressure, elasticity, rarefaction, and condensation.
- Aeronomy
- The study of the upper regions of the atmosphere where ionization, dissociation, and chemical reactions take place.
- Aeropause
- A region of indeterminate limits in the upper atmosphere, considered as a boundary or transition region between the denser portion of the atmosphere and space.
- Altocumulus
- Composed of flattened, thick, gray, globular masses, this middle cloud genus is primarily made of water droplets.
- Altocumulus Castellanus
- A middle cloud with vertical development that forms from altocumulus clouds.
- Altostratus
- Middle cloud genus is composed of water droplets, and sometimes ice crystals.
- Anemometer
- A sensor that measures wind speed.
- Anticyclone
- A relative pressure maximum. An area of pressure that has diverging winds and a rotation opposite to the earth′s rotation.
- Apparent Horizon
- Where the shy appears to meet the Earth.
- Atmospheric Windows
- The spectral bands in which the atmosphere least affects the transmission of radiant energy.
- Automated Surface Observing System
- This system is a collection of automated weather instruments that collect data.
- Automatic Weather Station
- A weather station that accurately and automatically measures and records meteorological variables over extended periods.
- Backing
- A counterclockwise shift in the wind direction in the Northern Hemisphere at a certain location. In the Southern Hemisphere, it is clockwise.
- Ball Lightning
- A relatively rare form of lightning, consisting of a reddish, luminous ball, of the order of 0.3m in diameter, which may move rapidly along solid objects or remain floating in midair.
- Barogram
- A continuous trace of air pressure variation with time, typically produced by a barograph.
- Barograph
- A recording type instrument that provides a continuous trace of air pressure variation with time.
- Barometric Pressure
- The total pressure exerted by the atmosphere.
- Beaufort Scale
- In 1805 Admiral Beaufort drew up a scale of wind strengths related to commonly observable phenomena.
- Ceiling Light
- An instrument consisting of a drum and an optical system that projects a narrow vertical beam of light onto a cloud base.
- Ceilometer
- An instrument that is used to measure the angular elevation of a projected light on the base of a cloud.
- Cirriform
- Clouds composed of small particles, mostly ice crystals.
- Cirrocumulus
- A cirriform cloud with vertical development, appearing as a thin sheet of small white puffs which give it a rippled effect.
- Cirrostratus
- A cirriform cloud that develops from cirrus spreading out into a thin layer, creating a flat sheetlike appearance.
- Cirrus
- Cirrus are thin, wispy clouds composed of ice crystals and often appear as veil patches or strands.
- Cloud Bank
- A well-defined cloud mass that can be observed at a distance.
- Cloudburst
- A sudden, heavy rainfall of a showery nature.
- Clouds
- A visible collection of minute particle matter, such as water droplets or ice crystals, in the free air.
- Cold Air Funnel
- Funnel clouds, usually short-lived, that develop from relatively small showers or thunderstorms when the air aloft is very in cold.
- Cold Core Thunderstorms
- Thunderstorms formed primarily due to steep lapse rates, especially when very cold air aloft overlies warmer surface air.
- Comma Cloud
- A feature seen on satellite images with a distinctive comma-shape.
- Contrail
- Acronym for CONdensation TRAIL. A cloud-like streamer or trail often seen behind aircraft flying in clear, cold, humid air.
- Crosswind
- Any wind that is blowing perpendicular to a line of travel.
- Cumuliform
- Clouds composed of water droplets that exhibit vertical development.
- Cumulonimbus
- A vertically developed cumulus cloud, often capped by an anvil-shaped cirriform cloud.
- Cumulonimbus Mammatus
- A portion of a cumulonimbus cloud that appears as a pouch or udder on the under surface of the cloud.
- Cumulus
- One of the three basic cloud forms.
- Cumulus Fractus
- Cumulus clouds that appear in irregular fragments.
- Cumulus Humilis
- Cumulus clouds with little or no vertical development characterized by a generally flat appearance.
- Cumulus Mediocris
- Cumulus clouds characterized by moderate vertical development with upper protuberances not very marked in appearance.
- Cup Anemometer
- A rotation-type anemometer consists of an array of three, or more, hemispherical cups mounted symmetrically about a vertical rotation axis.
- Cyclogenesis
- The process that creates a new low pressure system or cyclone, or intensifies a pre-existing one.
- Cyclone
- An area of closed pressure circulation with rotating and converging winds, the centre of which is a relative pressure minimum.
- Dew Point
- The temperature at which water vapour begins to condense.
- Dew Point Hygrometer
- An instrument used for determining the dewpoint.
- Dropsonde
- A modified radiosonde package that is dropped by parachute from an aircraft to obtain temperature, pressure, and humidity profiles of the atmosphere below flight level.
- Dry Bulb Thermometer
- A thermometer used to measure the ambient temperature.
- Environmental Lapse Rate
- The rate at which the air temperature decreases as you move higher in the atmosphere.
- Flanking Line
- A line of attached cumulus or towering cumulus clouds of descending height.
- Fractus
- The elements of cumulus and stratus clouds that appear in irregular fragments.
- Free Atmosphere
- The layer of the atmosphere above the boundary layer that is not affected by surface friction.
- Global Warming
- The prediction that climate will warm as a result of the addition to the atmosphere of humanly produced greenhouse gases.
- Globe Lightning
- Another name for Ball Lightning.
- Greenhouse Gases
- The three most powerful long lived greenhouse gases in the atmosphere are: Carbon Dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O).
- Hair Hygrometer
- Measures atmospheric relative humidity by means of the variation in length of a bundle of human hairs as they adsorb atmospheric water vapour.
- Heat Island Effect
- A dome of elevated temperatures over an urban area caused by structural and pavement heat fluxes, and pollutant emissions.
- Horizontal Range
- The maximum distance in the horizontal direction that one can see.
- Hot-Wire Anemometer
- Uses the wind induced changes in the temperature of a metal wire that is heated by an electric current and cooled by convective heat loss.
- Hydrologic Cycle
- The cycle of water from evaporation through condensation to precipitation.
- Hygrometer
- A tool for measuring the humidity of the air.
- Hypobaric
- Pertaining to low atmospheric pressure.
- Ionospheric Storms
- Disturbances in the earth′s magnetic field that make communications practical only at lower frequencies.
- Lenticular Cloud
- A cloud species which has elements resembling smooth lenses or almonds and more or less isolated.
- Lightning
- An atmospheric discharge of electricity usually accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms.
- Linke Turbidity Factor
- A measure of atmospheric turbidity, equal to the ratio of total optical depth to the Rayleigh optical depth.
- Mackerel Sky
- The name given to cirrocumulus clouds with small vertical extent and composed of ice crystals.
- Mammatocumulus
- An obsolete term for cumulonimbus mammatus, it is a portion of a cumulonimbus cloud that appears as a pouch or udder on the under surface of the cloud.
- Mare Tail
- The name given to thin, wispy cirrus clouds composed of ice crystals that appear as veil patches or strands, often resembling a horse′s tail.
- Mesopause
- Extremely cold region of the earth′s atmosphere at an altitude of approximately 80 km, representing the boundary between the mesosphere and the overlying thermosphere.
- Meteorograph
- A collection of automatic meteorological recording instruments, often times describing the package that is carried aloft on an instrument platform.
- Meteorological
- Of or pertaining to atmospheric phenomena, especially weather and weather conditions.
- Micrometeorology
- The detailed study of the weather at a specific location.
- Minimum Thermometer
- A thermometer designed to automatically register the lowest temperature attained during any time interval before it is set.
- Nimbostratus
- This cloud exhibits a combination of rain or snow, and sometimes the base of the cloud cannot be seen because of the heaviness of precipitation.
- Noctilucent Clouds
- Rarely seen clouds of tiny ice particles that form approximately 75 to 90 kilometers above the earth′s surface.
- Overcast
- The amount of sky cover for a cloud layer that is 8/8ths, based on the summation layer amount for that layer.
- Pentad
- A period of 5 days.
- Pilot Balloon
- A balloon that ascends through the atmosphere at a constant rate and is tracked by a theodolite in order to obtain timed data for the computation of the wind speed and wind direction at various levels in the upper air above the station.
- Pressure Gradient
- The change in pressure per unit of distance.
- Psychrometric Chart
- A chart that shows relationship between the temperature, pressure and moisture content of the air.
- Psychrometry
- The study of air-vapour mixtures.
- Radiosonde
- A small, expendable, balloon-borne instrument package with a radio transmitter used to measure the air temperature, pressure and humidity of the atmosphere above the earth′s surface.
- Rain Bucket
- Device for measuring rain fall.
- Rain Gauge
- Instrument used to measure the total amount of precipitation that falls upon a given unit area during a specified time interval.
- Rocket Sounding
- A probe of the upper atmosphere with a meteorological rocket to produce a record of the vertical variation of a weather element such as air temperature, density, composition or winds.
- Rocketsonde
- An instrument package carried aloft by a meteorological rocket to make a measure one or more weather elements in a sounding of the upper atmosphere.
- Roll Cloud
- A relatively rare, low-level, horizontal, tube-shaped cloud.
- Rotor Cloud
- An altocumulus cloud formation that can be found in the lee of a mountain or similar barrier.
- Sferics Observation
- An evaluation, from one or more sferics receivers, of the location of weather conditions with which lightning is associated.
- Sferics Receiver
- An instrument which measures, electronically, the direction of arrival, intensity, and rate of occurrence of atmospherics.
- Sky Cover
- The amount of the celestial dome that is hidden by clouds or obscurations.
- Sounding
- Any probe of the environment made to obtain information at various levels.
- Sporadic E Layer
- Irregular, cloud-like patches of unusually high ionization.
- Stratiform
- Clouds composed of water droplets that exhibit no or have very little vertical development.
- Stratocumulus
- A low cloud composed of layers or patches of cloud elements.
- Stratosphere
- Located between the troposphere and the ionosphere.
- Stratus
- One of the three basic cloud forms.
- Stratus Fractus
- Stratus clouds that appear in irregular fragments.
- Summation Layer Amount
- The amount of sky cover for each layer is given in eighths of sky cover attributable to clouds or obscurations.
- Temperature
- A measure as to whether two bodies are hot or cold relative to one another.
- Temperature Humidity Index
- Actual temperature and humidity of air sample compared to air at standard conditions.
- Temperature Inversion
- The condition in which warm air is formed above a layer of cool air that is near the earth′s surface.
- Thermogram
- A continuous trace of temperature variation with time, typically produced by a thermograph.
- Thermohygrograph
- An instrument for measuring humidity and temperature.
- Thermometer
- An instrument for measuring temperature.
- Thermosphere
- The region of the Earth′s atmosphere above the mesopause, starting at 80 km altitude, where the air temperature increases with altitude.
- Towering Cumulus
- Another name for cumulus congestus.
- Tropopause
- The cold region in t earth′s atmosphere located about 10 km above the surface.
- Troposphere
- The portion of the atmosphere, closest to the surface of the earth, where all weather phenomena take place.
- True Altitude
- Actual height above sea level; calibrated altitude corrected for air temperature.
- Undercast
- An opaque cloud layer viewed from an observation point above the layer.
- Upwind
- The direction from which the wind is blowing. Also the windward side of an object.
- Vapour Trail
- A cloud like streamer or trail often seen behind aircraft flying in clear, cold, humid air.
- Veering
- A clockwise shift in the wind direction in the Northern Hemisphere at a certain location. In the Southern Hemisphere, it is counterclockwise.
- Virga
- Streaks or wisps of precipitation, such as water or ice particles, that fall from clouds but evaporate before reaching the ground.
- Wall Cloud
- An abrupt lowering of a cloud from its parent cloud base, a cumulonimbus or supercell, with no visible precipitation underneath.
- Water Cycle
- Also known as the Hydrologic Cycle.
- Wet Bulb Thermometer
- A wet wick is placed over a standard thermometer and air is blown across the surface. The temperature depends on how much moisture is in the air.
- Wind
- Air in motion relative to t earth′s surface, caused by the average movement of a large number of molecules of air.
- Wind Shear
- The difference between wind velocity measured at two specific locations divided by the distance between those two positions.
- Wind Speed
- Normally measured relative to the earth′s surface.
- Wind Vane
- A sensor used to measure wind direction.
- Wind Velocity
- A vector quantity that describes wind motion in terms of wind speed and wind direction.
- Zonal Wind
- Atmospheric wind component which flows along the latitude.
