Glossary
Air :: The mixture of gases that comprise the Earth’s atmosphere. The principle constituents include Nitrogen, Oxygen, Argon, Carbon Dioxide, and Water Vapor.
Air Mass :: A large body of air with homogeneous temperature and moisture characteristics.
Analog Forecast :: An method of forecasting that uses historical weather events and wind patterns similar to the current conditions.
Atmosphere :: The air portion of the physical environment that encircles a planet. The Earth’s atmosphere is held near the surface by the Earth’s gravitational attraction.
Atmospheric Pressure :: The weight of the atmosphere at a given point.
Barometric Pressure :: The pressure exerted by column of air due to gravitational attraction.
Blizzard :: A severe weather condition characterized by low temperatures, winds 35 mph or greater, and sufficient falling and/or blowing snow in the air to reduce visibility to ¼ mile or less for a duration of at least 3 hours.
Blowing Snow :: Snow that is raised by the wind to heights of six feet or greater.
Box Plot :: A graph that depicts the variation and central tendency of data.
Broadcloth :: Heavy cloth, often folded double for increased durability and warmth.
Chronologically :: In the order that things happened; from first to last.
Climate :: A representation of a region’s weather over a given period of time. A region's climate is often characterized in terms of the average and variation of the climate system over periods of a month or more.
Climatology Forecast ::A forecast based upon the climatologocial statistics of a region.
Cold Front :: The leading edge of an advancing cold air mass that is displacing the warmer air in its path. Generally, with the passage of a cold front, the temperature and moisture decrease, the atmospheric pressure rises, and the winds shift. Precipitation is generally found in the vicinity of the cold front. If the cold front is fast moving, a squall line may develop ahead of the front.
Conceptual Model :: A simple representation, in words or figures, of a complex process or idea.
Context :: The circumstances or setting surrounding an event or story.
Convergence :: Horizontal air movement coming together from different directions. If convergence occurs at the surface of the Earth, the air must rise since it has no other place to go.
Cultural Scene :: A reoccuring setting of social interaction for a cultural group, like a teachers' lounge for educators or a restaurant's kitchen for cooks and wait staff.
Cyclogenesis :: The development of a cyclone. Surface temperature gradients, jet streams, and tall mountain ranges can lead to extratropical cyclogenesis.
Cyclolysis :: Any weakening of >cyclonic circulation in the atmosphere; the opposite of cyclogenesis.
Cyclone :: A low pressure system enclosed by rotating winds that converge at the surface of the Earth. The center of a cyclone is a relative minimum of atmospheric pressure. The circulation of winds around a cyclone are counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Daily Maximum :: The highest value (e.g. warmest temperature) recorded for a given day.
Daily Minimum :: The lowest value (e.g. coldest temperature) recorded for a given day.
Daily Mean :: The average temperature for a day computed by averaging either the hourly readings or, more commonly, the maximum and minimum temperatures.
Divergence :: Horizontal air movements flowing outward from one another. If divergence occurs at the surface of the Earth, air must flow down from above in order to take its place.
Drifting Snow :: Snow particles blown from the ground by the wind to a height of less than six feet.
Drought :: A period of abnormally dry weather sufficiently long enought to cause a serious hydrological imbalance
Emphasis :: Attention or effort devoted to something to make it more noticeable or because it is important
Extratropical Cyclones :: Also called the midlatitude cyclone, it is a low-pressure weather systems that occur outside the tropics and can often cause wet and windy weather. Norwegian meteorologists discovered that these cyclones are associated with fronts and that they have a definite life cycle, growing from birth to maturity to death over the course of several days.
Filling :: An increase in the central atmospheric pressure of a cyclone or low pressure system.
Folklore Forecasts ::Short sayings that try to predict the weather based on sky conditions, special days of the calendar, or the behavior of animals.
Forecast ::See weather forecast.
Histogram :: A graph of a dataset made up of rectangular bars. Each bar is of the same width, which is proportional to the range of values. The height of the bars is proportional to the number of occurrences in each particular value range.
Hip boots :: Rubber boots that reach mid or upper thigh and attach to a belt that holds them up
Hypothermia :: A condition which occurs when the temperature of one’s body falls below normal. It is the failure of the body to maintain adequate production of heat under conditions of extreme cold.
Ice :: The solid form of water. It can be found in the atmosphere in the form of ice crystals, snow, ice pellets, and hail.
Interquartile Range :: the difference between the 1st and 3rd quartiles, or 25th and 75th percentiles.
Isobar :: A line drawn on a weather map connecting points of equal atmospheric pressure.
Isotherm :: A line drawn on a weather map connecting points of equal temperature.
Jargon :: Specialized terms and talk shared by members of a cultural group.
Knot :: A of speed; one nautical mile per hour. It is equal to 1.1508 miles (1.852 km) per hour or 1.687 ft per second.
Lake Effect Snow :: Snow showers that are created when cold dry air passes over a large warmer lake.
Low Pressure System :: An area with a central relative minimum in atmospheric pressure that has convergent winds at the Earth’s surface and rotates in the same direction as the Earth. This is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Also known as a cyclone.
Maritime Polar Air Mass :: An air mass influenced by the sea and originating North of the midlatitudes.
Median :: The value in a data set that has an equal number of values falling above and below it. For an odd number of values, arranged from lowest to highest, the median is simply the middle value. For an even number of values, the median is the average of the two values at the center. (Also called the 50th percentile, or 2nd quartile).
Midlatitude Cyclone :: Also called an extratropical cyclone, it is a low-pressure weather systems that occur outside the tropics and can often cause wet and windy weather. Norwegian meteorologists discovered that these cyclones are associated with fronts and that they have a definite life cycle, growing from birth to maturity to death over the course of several days.
Millibar :: Units of atmospheric pressure. The average atmospheric pressure at sea level is 1013.25 mb.
Mode :: The most frequently occurring value in a data set.
Normal :: The mean value of a weather element, such as temperature or precipitation, averaged over a period of 30 years.
Norwegian cyclone model :: A conceptual model of the midlatitude cyclone. Though simplified, it can help explain most of the characteristics of a real-life, deadly midlatitude cyclone.
Nowcast :: A forecast of the weather for the next few hours.
Numerical Forecast :: The prediction of weather or climate using mathematical approximations to the equations of motion and conservation.
Occluded Ffront :: A front that forms as a cyclone moves deepter into colder air.
Occupational folklore is the various skills, techniques, verbal expressions, and customs performed within a certain occupation or workplace.
Percentile :: The Nth percentile is the value for which at least N percent of the data is at an equal or lesser value.
Persistence Forecast ::A forecast that assumes that tomorrow’s weather will be the same as today ’s weather.
Personal Experience Narrative (PEN) :: An account of a personal experience told in first-person.
Precipitation :: Water, liquid or solid that falls from clouds and reaches the ground.
Pressure Gradient :: The change in atmospheric pressure over some distance.
Quartile :: The 25th, 50th and 75th percentiles make up the 1st, 2nd, and 3rd quartiles, respectively.
Range :: The difference between the maximum and minimum values.
Repetition :: Saying a word or phrase more than once, or saying it a different way so that the meaning is repeated
Scattering ::The process by which light rays change direction of propagation through the interaction with particles, such as molecules aerosols and cloud particles.
Sea Level Pressure :: What the atmospheric pressure would be if the observation were taken at mean sea level.
Severe Blizzard :: A severe weather condition characterized by temperatures near or below 10ºF, winds exceeding 45 mph, and visibility reduced by snow to near zero.
Snow :: Precipitation in the form of ice crystals or aggregates of crystals.
Snowfall :: The rate at which snow falls, usually expressed in inches of snow depth over a six hour period.
Squall line: A line of intense thunderstorms.
Temperature :: The measure of molecular motion or the degree of heat of a substance.
Thermometer :: An instrument used for measuring temperature.
Trend Forecast ::A weather forecast that assumes that tomorrow’s weather will change due to approaching weather systems that are not changing.
Tropopause :: The boundary between the troposphere and the stratosphere.
Trough :: An elongated area of low atmospheric pressure, generally indicated by the isobars dipping southward in the Northern Hemisphere.
Visibility :: A measure of how far one can see through the atmosphere with the unaided eye.
Waders :: Waist or chest high rubber (nowadays often neoprene) waterproof pants or overalls worn over other clothing.
Warning :: A forecast issued when severe weather has developed, is already occurring and reported, or is detected by radar. Warnings state a particular hazard or imminent danger, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, heavy snows, etc.
Watch :: A forecast issued in advance of a severe weather event to alert the public to the possibility of a particular hazard, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, heavy snows, etc.
Waterfowl :: Large swimming birds, like geese and ducks.
Water Vapor: The gas phase of water, not to be confused with steam which consists of tiny droplets of liquid water.
Weather :: The state of the atmosphere at a specific time.
Weather Forecast :: An assessment of the future state of the weather.
Whiteout :: When visibility is near zero due to blizzard conditions or on sunless days when clouds and surface snow seem to blend, erasing the horizon and creating a completely white vista.
Wind :: Air that flows in relation to the Earth’s surface, generally horizontally. There are four properties of wind that are measured: direction, speed, character, and shifts.
Wind Barb :: A means of representing wind speed in the plotting of a weather map. One barb represents 10 knots and a half-barb represents 5 knots, and a triangle 50 knots.
Winter :: The period between the Winter Solstice (around December 21) and the Vernal Equinox (around March 20).
