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50 common weather terms, explained

  • 50 common weather terms, explained

    In the year 350 B.C., the Greek philosopher Aristotle gave one of the earliest descriptions of weather patterns in a text called “Meteorologica,” which translates into “Meteorology.” It included some of mankind’s first attempts to observe and record natural phenomena like water evaporation and earthquakes. Although it was a far cry from the Weather Channel, “Meteorologica” was the start of something that had eluded human beings for time immemorial: the ability to understand—and even predict—the weather.

    According to the National Weather Service, modern weather forecasting is a $7 billion industry—and for good reason. Despite all the advanced technology of modern society, humans are still pretty much at the mercy of the elements. America’s GDP can fluctuate by more than $1.34 trillion depending on the weather. In 2017 alone, nearly 60,000 weather events killed 592 people in the United States and injured 4,270 more, with flash floods, tropical storms, heat, tornadoes, ice storms, and thunderstorms doing most of the damage.

    Weather forecasters are easy targets because, like football referees, people tend to take notice only when they get it wrong. The reality, however, is that meteorologists are right in astonishing percentages. When weathermen and women issue seven-day forecasts, they’re accurate about 80% of the time—90% for five-day forecasts. If someone had told Aristotle that human beings would one day be able to accurately predict the weather nine times out of 10, five days in advance, he likely would have laughed at their overactive imagination.

    It’s important to note that “climate” and “weather” are not interchangeable terms. Weather describes the short-term—day-to-day and hour-to-hour—state of the atmosphere, including temperature, precipitation, wind, and visibility. Climate, on the other hand, measures average weather patterns over several decades. Global-warming deniers often cite anomalies like warm spells in the winter as evidence backing their point of view, when they are referencing the weather, not the climate.

    Stacker used a variety of scientific sources to compile a list of 50 common weather terms. Here’s a look at the phrases, words, and terminology that dominate weather reports, which are correct far more frequently than the people who craft them are given credit for.

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  • Polar vortex

    The menacing phrase “polar vortex” is a relatively new term for winter weather forecasting, but meteorologists have understood it as a concept for decades. A polar vortex occurs when a large section of very cold air, usually the coldest in the entire northern hemisphere, is pushed down the North American continent as far south as the Midwestern and Northeastern United States.

    After a summer off, the polar vortex re-formed on the North Pole during September 2019 and was classified as about average for that time of year.

     

  • Atmospheric (barometric) pressure

    Humans inhabit the very bottom of the Earth’s atmosphere and everything above creates atmospheric pressure. High-pressure systems form when downward pressure creates a clockwise air rotation, unlike low-pressure systems, which generate counter-clockwise rotation. Both phenomena, which are measured with electronic sensors called barometers, are critical to predicting weather events like precipitation.

     

  • Inch of mercury

    Inch of mercury is a unit used to measure air pressure. It represents the amount of pressure the atmosphere places on a one-inch column of mercury under standard gravity at zero degrees Celsius.

    [Pictured: A vector illustration of a barometer which measures atmospheric pressure in inches of mercury] 

     

  • Ball lightning

    Lightning in its traditional form is frightening and deadly on its own, but ball lightning is scary even in the context of instant electrocution from the heavens. Also known as globe lightning, the phenomenon has baffled and terrified humans for centuries. Ball lightning is a floating, colorized sphere of energy that spins off from thunderstorms and sometimes crashes through windows with deadly results—it appears to be attracted to ions that accumulate on glass.

    [Pictured: This is an artist rendering of ball lightning]

     

  • Troughs and ridges

    On weather forecasts, troughs and ridges are represented by U-shaped patterns, often overlayed with directional arrows. These indicators of pressure are important clues in forecasting weather. Precipitation forms around troughs while ridges indicate dry conditions.

    [Pictured: Weather map graphic of the United States of America highlighting troughs and ridges]

  • Tropical storm

    People sometimes use the terms “tropical storm” and “hurricane” interchangeably, but one is actually an evolution of the other. Tropical storms form in the same places and under the same conditions as hurricanes, but they achieve maximum sustained wind of just 39–73 mph. If a tropical storm’s maximum sustained winds hit 74 mph, it becomes a hurricane.

     

  • Tropical depression

    Before a weather event graduates into a tropical storm, it’s a tropical depression. The infant stage of a hurricane, a tropical depression is a tropical cyclone with maximum sustained winds up to 38 mph.

  • Dew point

    Dew point represents the temperature to which air would have to be cooled to reach a level of moisture saturation. When it reaches the dew point, droplets of water, or dew, begin to form on solid objects like grass and cars.

  • Relative humidity

    Relative humidity is closely related to dew point, but the two terms are not interchangeable. This term describes the amount of atmospheric moisture that exists relative to the amount that would exist if the air were saturated.

  • Wind chill

    Everyone in America above a certain latitude knows there are two temperatures they have to consider when getting dressed in the morning in winter—the actual temperature reading and the one that counts: the wind chill factor. Also known as the “feels-like” temperature, wind chill represents how cold the weather feels on human skin when the chilling effect of the wind is taken into consideration.

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