associated with a heavy or severe thunderstorm over Enschede, Netherlands]]A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather. It may be marked by strong wind, thunder and lightning (a thunderstorm), heavy precipitation, such as ice (ice storm), or wind transporting some substance through the atmosphere (as in a dust storm, snowstorm, hailstorm, etc).
There are many varieties and names for storms.
- Ice Storm - Ice storms are one of the most dangerous forms of winter weather. When surface temperatures are below freezing, but a thick layer of above freezing air remains aloft above ground level, rain can fall into the freezing layer and freeze upon impact into a glaze. In general, 8 mm or 1/4" of accumulation is all that is required, especially in combination with breezy conditions, to start downing power lines as well as tree limbs.City of Kent, Washington. Snow/Ice Storm. Retrieved on 2006-11-26. Ice storms also make unheated road surfaces too slick to drive upon. Ice storms can vary in time range from hours to days and can cripple both small towns and large urban centers alike.
- Blizzard - There are varying definitions for blizzards, both over time and by location. In general, a blizzard is accompanied by gale-force winds (winds of around 35 kts/40 mph or greater), heavy snow (accumulating at a rate of a 5+ cm/2+ in per hour), and very cold conditions (below approximately -10C/14F). As of late, the temperature criteria has fallen out of the definition across the United StatesUniversity Corporation for Atmospheric Research. Winter Storms. Retrieved on 2006-11-26.
- Snowstorm - A heavy fall of snow (accumulating at a rate of a 5+ cm/2+ in per hour) that lasts several hours. Snow storms, especially ones with a high liquid equivalent and breezy conditions, can down tree limbs, cut off power, and paralyze travel over a large region. ]]
- Ocean Storm - Storm conditions out at sea are defined as having sustained winds of 48 kts/55 mph or greater.Ocean Prediction Center. Terminology and Weather Symbols. Retrieved on 2006-11-26. Usually just referred to as a storm, these systems can sink vessels of all types and sizes out at sea.
- Dust devil - a small, localized updraft of rising air.
- Windstorm - a severe weather condition indicated by high winds and with little or no rain, like European windstorm.
- Squall - sudden onset of wind increase of at least 16 knots or greater sustained for at least one minute.
- Gale - An extratropical storm with sustained winds between 34-48 kts/39-55 mph.
- Thunderstorm - A thunderstorm is a type of storm that generates lightning and the attendant thunder. It is normally accompanied by heavy precipitation. Thunderstorms occur throughout the world, with the highest frequency in tropical rainforest regions where there are conditions of high humidity and temperature along with atmospheric instability. These storms occur when high levels of condensation form in a volume of unstable air that generates deep, rapid, upward motion in the atmosphere. The heat energy creates powerful rising air currents that swirl upwards to the tropopause. Cool descending air currents produce strong downdraughts below the storm. After the storm has spent its energy, the rising currents die away and downdraughts break up the cloud. Individual storm clouds can measure 2-10 km across.
- Tropical Cyclone - A tropical cyclone is a storm system with a closed circulation around a centre of low pressure, fueled by the heat released when moist air rises and condenses. The name underscores their origin in the tropics and their cyclonic nature. They are distinguished from other cyclonic storms such as nor'easters and polar lows by the heat mechanism that fuels them, which makes them "warm core" storm systems.
in Hong Kong. Sanvu was the first typhoon in 2005 that passed through the city.]]
- Tornado - A tornado is a violent, destructive wind storm occurring on land. Usually its appearance is that of a dark, funnel-shaped cyclone. Often tornadoes are preceded by a thunderstorm and a wall cloud. They are often called the most destructive of storms, and while they form all over the world, the American Midwest is the most prone area, especially Oklahoma and Kansas.
A strict meteorological definition of a terrestrial storm is a wind measuring 10 or higher on the Beaufort scale, meaning a wind speed of 24.5 m/s (89 km/h, 55 mph) or more; however, popular usage is not so restrictive. Storms can last anywhere from 12 to 200 hours, depending on season and geography. The east and northeast storms are noted for the most frequent repeatability and duration, especially during the cold period. Big terrestrial storms alter the oceanographic conditions that in turn may affect food abundance and distribution: strong currents, strong tides, increased siltation, change in water temperatures, overturn in the water column, etc.
on Jupiter]]Storms are not unique to Earth; other heavenly bodies with a sufficient atmosphere (gas giants in particular) also undergo stormy weather. A famous example is the Great Red Spot on Jupiter. Though technically a hurricane, it is larger than the earth and has been raging for at least 340 years, when it was observed by astronomer Galileo Galilei. Neptune also had its own lesser known Great Dark Spot.In September of 1994 Hubble telescope using Wide Field Planetary Camera 2 imaged the storms on Saturn, generated by upwelling of warmer air, similar to a terrestrial thunderhead. The east-west extent of the same-year storm was equal to the diameter of Earth (ca. 7,900 miles). The storm was observed earlier in September, 1990 and acquired the name Dragon Storm.