Storm
A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning, heavy precipitation, heavy freezing rain, strong winds, wind transporting some substance through the atmosphere such as in a dust storm, among other forms of severe weather.
Storms have the potential to harm lives and property via storm surge, heavy rain or snow causing flooding or road impassibility, lightning, wildfires, and vertical and horizontal wind shear. Systems with significant rainfall and duration help alleviate drought in places they move through. Heavy snowfall can allow special recreational activities to take place which would not be possible otherwise, such as skiing and snowmobiling.
The English word comes from Proto-Germanic sturmaz meaning "noise, tumult"; a synonym is tempest, of French origin.
Storms are created when a center of low pressure develops with the system of high pressure surrounding it. This combination of opposing forces can create winds and result in the formation of storm clouds such as cumulonimbus. Small localized areas of low pressure can form from hot air rising off hot ground, resulting in smaller disturbances such as dust devils and whirlwinds.
Types
There are many varieties and names for storms:- Blizzard There are varying definitions for blizzards, both over time and by location. In general, a blizzard is accompanied by gale-force winds, heavy snow, and very cold conditions. Lately, the temperature criterion has fallen out of the definition across the United States.
- Bomb cyclone A rapid deepening of a mid-latitude cyclonic low-pressure area, typically occurring over the ocean, but can occur over land. The winds experienced during these storms can be as powerful as that of a typhoon or hurricane.
- Coastal storm Large wind waves and/or storm surge that strike the coastal zone. Their impacts include coastal erosion and coastal flooding.
- Derecho A derecho is a widespread, long-lived, straight-line wind storm that is associated with a land-based, fast-moving group of severe thunderstorms.
- Dust devil A small, localized updraft of rising air.
- Dust storm A situation in which winds pick up large quantities of sand or soil, greatly reducing visibility.
- Firestorm Firestorms are conflagrations which attain such intensity that they create and sustain their own wind systems. It is most commonly a natural phenomenon, created during some of the largest bush fires, forest fires, and wildfires. The Peshtigo Fire is one example of a firestorm. Firestorms can also be deliberate effects of targeted explosives, such as occurred as a result of the aerial bombings of Dresden. Nuclear detonations generate firestorms if high winds are not present.
- Gale An extratropical storm with sustained winds between 34 and 48 knots.
- Hailstorm A type of storm that precipitates round chunks of ice. Hailstorms usually occur during regular thunderstorms. While most of the hail that precipitates from the clouds is fairly small and virtually harmless, there are occasional occurrences of hail greater than 2 inches in diameter that can cause much damage and injuries.
- Ice storm Ice storms are one of the most dangerous forms of winter storms. When surface temperatures are below freezing, but a thick layer of above-freezing air remains aloft, rain can fall into the freezing layer and freeze upon impact into a glaze of ice. In general, of accumulation is all that is required, especially in combination with breezy conditions, to start downing power lines as well as tree limbs. 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 small towns and large metropolitan cities alike.
- Microburst A very powerful windstorm produced during a thunderstorm that only lasts a few minutes.
- Ocean Storm or sea storm Storm conditions out at sea are defined as having sustained winds of 48 knots or greater. Usually just referred to as a storm, these systems can sink vessels of all types and sizes.
- Nor'westers A powerful storm coming from North-western direction, associated with heavy gusts, hail and thunderstorms. Usually occurs in Eastern India and Bangladesh in the late Spring and early Summer.
- Snowstorm A heavy fall of snow accumulating at a rate of more than 5 centimeters 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 connections and paralyze travel over large regions.
- Squall Sudden onset of wind increase of at least 16 knots or greater sustained for at least one minute.
- Thunderstorm A thunderstorm is a type of storm that generates both lightning and 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.
- Tornado A tornado is a violent, destructive whirlwind storm occurring on land. Usually its appearance is that of a dark, funnel-shaped cloud. Often tornadoes are preceded by or associated with thunderstorms and a wall cloud. They are often called the most destructive of storms, and while they form all over the planet, the interior of the United States is the most prone area, especially throughout Tornado Alley.
- 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 its origin in the tropics and their cyclonic nature. Tropical cyclones 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. Tropical cyclones form in the oceans if the conditions in the area are favorable, and depending on their strength and location, there are various terms by which they are called, such as tropical depression, tropical storm, hurricane and typhoon.
- Wind storm A storm marked by high wind with little or no precipitation. Windstorm damage often opens the door for massive amounts of water and debris to cause further damage to a structure. European windstorms and derechos are two type of windstorms. High wind is also the cause of sandstorms in dry climates.
Classification
Extraterrestrial storms
Storms do not only occur on Earth; other planetary bodies with a sufficient atmosphere also undergo stormy weather. The Great Red Spot on Jupiter provides a well-known example. Though technically an anticyclone, with greater than hurricane wind speeds, it is larger than the Earth and has persisted for at least 340 years, having first been observed by astronomer Giovanni Domenico Cassini. Neptune also had its own lesser-known Great Dark Spot.In September 1994, the Hubble Space Telescope – using Wide Field Planetary Camera 2 – imaged storms on Saturn generated by upwelling of warmer air, similar to a terrestrial thunderhead. The east–west extent of the same-year storm equaled the diameter of Earth. The storm was observed earlier in September 1990 and acquired the name Dragon Storm.
The dust storms of Mars vary in size, but can often cover the entire planet. They tend to occur when Mars comes closest to the Sun, and have been shown to increase the global temperature.
One particularly large Martian storm was exhaustively studied up close due to coincidental timing. When the first spacecraft to successfully orbit another planet, Mariner 9, arrived and successfully orbited Mars on 14 November 1971, planetary scientists were surprised to find the atmosphere was thick with a planet-wide robe of dust, the largest storm ever observed on Mars. The surface of the planet was totally obscured. Mariner 9's computer was reprogrammed from Earth to delay imaging of the surface for a couple of months until the dust settled, however, the surface-obscured images contributed much to the collection of Mars atmospheric and planetary surface science.
Two extrasolar planets are known to have storms: HD 209458 b and HD 80606 b. The former's storm was discovered on 23 June 2010, and measured at, while the latter produces winds of across the surface. The spin of the planet then creates giant swirling shock-wave storms that carry the heat aloft.
Effects on human society
Shipwrecks are common with the passage of strong tropical cyclones. Such shipwrecks can change the course of history, as well as influence art and literature. A hurricane led to a victory of the Spanish over the French for control of Fort Caroline, and ultimately the Atlantic coast of North America, in 1565.Strong winds from any storm type can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. In the United States, major hurricanes comprise just 21% of all landfalling tropical cyclones, but account for 83% of all damage. Tropical cyclones often knock out power to tens or hundreds of thousands of people, preventing vital communication and hampering rescue efforts. Tropical cyclones often destroy key bridges, overpasses, and roads, complicating efforts to transport food, clean water, and medicine to the areas that need it. Furthermore, the damage caused by tropical cyclones to buildings and dwellings can result in economic damage to a region, and to a diaspora of the population of the region.
The storm surge, or the increase in sea level due to the cyclone, is typically the worst effect from landfalling tropical cyclones, historically resulting in 90% of tropical cyclone deaths. The relatively quick surge in sea level can move miles/kilometers inland, flooding homes and cutting off escape routes. The storm surges and winds of hurricanes may be destructive to human-made structures, but they also stir up the waters of coastal estuaries, which are typically important fish breeding locales.
Cloud-to-ground lightning frequently occurs within the phenomena of thunderstorms and have numerous hazards towards landscapes and populations. One of the more significant hazards lightning can pose is the wildfires they are capable of igniting. Under a regime of low precipitation thunderstorms, where little precipitation is present, rainfall cannot prevent fires from starting when vegetation is dry as lightning produces a concentrated amount of extreme heat. Wildfires can devastate vegetation and the biodiversity of an ecosystem. Wildfires that occur close to urban environments can inflict damages upon infrastructures, buildings, crops, and provide risks to explosions, should the flames be exposed to gas pipes. Direct damage caused by lightning strikes occurs on occasion. In areas with a high frequency for cloud-to-ground lightning, like Florida, lightning causes several fatalities per year, most commonly to people working outside.
Precipitation with low potential of hydrogen levels, otherwise known as acid rain, is also a frequent risk produced by lightning. Distilled water, which contains no carbon dioxide, has a neutral pH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are bases. "Clean" or unpolluted rain has a slightly acidic pH of about 5.2, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid, but unpolluted rain also contains other chemicals. Nitric oxide present during thunderstorm phenomena, caused by the splitting of nitrogen molecules, can result in the production of acid rain, if nitric oxide forms compounds with the water molecules in precipitation, thus creating acid rain. Acid rain can damage infrastructures containing calcite or other solid chemical compounds containing carbon. In ecosystems, acid rain can dissolve plant tissues of vegetations and increase acidification process in bodies of water and in soil, resulting in deaths of marine and terrestrial organisms.
Hail damage to roofs often goes unnoticed until further structural damage is seen, such as leaks or cracks. It is hardest to recognize hail damage on shingled roofs and flat roofs, but all roofs have their own hail damage detection problems. Metal roofs are fairly resistant to hail damage, but may accumulate cosmetic damage in the form of dents and damaged coatings. Hail is also a common nuisance to drivers of automobiles, severely denting the vehicle and cracking or even shattering windshields and windows. Rarely, massive hailstones have been known to cause concussions or fatal head trauma. Hailstorms have been the cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 9th century in Roopkund, Uttarakhand, India. The largest hailstone in terms of diameter and weight ever recorded in the United States fell on 23 July 2010, in Vivian, South Dakota in the United States; it measured in diameter and in circumference, weighing in at. This broke the previous record for diameter set by a hailstone diameter and circumference which fell in Aurora, Nebraska in the United States on 22 June 2003, as well as the record for weight, set by a hailstone of that fell in Coffeyville, Kansas in 1970.
Various hazards, ranging from hail to lightning can affect outside technology facilities, such as antennas, satellite dishes, and towers. As a result, companies with outside facilities have begun installing such facilities underground, to reduce the risk of damage from storms.
Substantial snowfall can disrupt public infrastructure and services, slowing human activity even in regions that are accustomed to such weather. Air and ground transport may be greatly inhibited or shut down entirely. Populations living in snow-prone areas have developed various ways to travel across the snow, such as skis, snowshoes, and sleds pulled by horses, dogs, or other animals and later, snowmobiles. Basic utilities such as electricity, telephone lines, and gas supply can also fail. In addition, snow can make roads much harder to travel and vehicles attempting to use them can easily become stuck.
The combined effects can lead to a "snow day" on which gatherings such as school, work, or church are officially canceled. In areas that normally have very little or no snow, a snow day may occur when there is only light accumulation or even the threat of snowfall, since those areas are unprepared to handle any amount of snow. In some areas, such as some states in the United States, schools are given a yearly quota of snow days. Once the quota is exceeded, the snow days must be made up. In other states, all snow days must be made up. For example, schools may extend the remaining school days later into the afternoon, shorten spring break, or delay the start of summer vacation.
Accumulated snow is removed to make travel easier and safer, and to decrease the long-term effect of a heavy snowfall. This process uses shovels and snowplows, and is often assisted by sprinkling salt or other chloride-based chemicals, which reduce the melting temperature of snow. In some areas with abundant snowfall, such as Yamagata Prefecture, Japan, people harvest snow and store it surrounded by insulation in ice houses. This allows the snow to be used through the summer for refrigeration and air conditioning, which requires far less electricity than traditional cooling methods.