Күшті желдің радиалды таралуы немесе төмен қарай соққысы

Strong surface level winds that radiate from a single point

In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originates under deep, moist convective conditions like Cumulus congestus or Cumulonimbus. Capable of producing damaging winds, it may sometimes be confused with a tornado, where high velocity winds circle a central area, and air moves inward and upward. These usually last for seconds to minutes. Downbursts are particularly strong downdrafts within thunderstorms (or deep, moist convection as sometimes downbursts emanate from cumulonimbus or even cumulus congestus clouds that are not producing lightning). Downbursts are most often created by an area of significantly precipitation cooled air that, after reaching the surface (subsiding), spreads out in all directions producing strong winds. Dry downbursts are associated with thunderstorms that exhibit very little rain, while wet downbursts are created by thunderstorms with significant amounts of precipitation. Microbursts and macrobursts are downbursts at very small and larger scales, respectively. A rare variety of dry downburst, the heat burst, is created by vertical currents on the backside of old outflow boundaries and squall lines where rainfall is lacking. Heat bursts generate significantly higher temperatures due to the lack of rain cooled air in their formation and compressional heating during descent. Down bursts are a topic of notable discussion in aviation, since they create vertical wind shear, which has the potential to be dangerous to aviation, especially during landing (or takeoff), where airspeed performance windows are the most narrow. Several fatal and historic crashes in past decades are attributed to the phenomenon and flight crew training goes to great lengths on how to properly recognize and recover from a downburst/wind shear event; wind shear recovery, among other adverse weather events, are standard topics across the world in flight simulator training that flight crews receive and must successfully complete. Detection and nowcasting technology was also implemented in much of the world and particularly around major airports, which in many cases actually have wind shear detection equipment on the field. This detection equipment helps air traffic controllers and pilots make decisions on the safety and feasibility of operating on or in the vicinity of the airport during storms.

A downburst is created by a column of sinking air that after hitting the surface spreads out in all directions and is capable of producing damaging straight line winds of over , often producing damage similar to, but distinguishable from, that caused by tornadoes. those accompanied with precipitation are known as wet downbursts. These generally are formed by precipitation cooled air rushing to the surface, but they perhaps also could be powered by strong winds aloft being deflected toward the surface by dynamical processes in a thunderstorm (see rear flank downdraft). Most downbursts are less than 2.5 mile (4 km) in extent: these are called microbursts. Downbursts larger than 2.5 mile (4 km) in extent are sometimes called macrobursts. The term microburst was defined by mesoscale meteorology expert Ted Fujita as affecting an area in diameter or less, distinguishing them as a type of downburst and apart from common wind shear which can encompass greater areas. Fujita also coined the term macroburst for downbursts larger than .

When rain falls below the cloud base or is mixed with dry air, it begins to evaporate and this evaporation process cools the air. The denser cool air descends and accelerates as it approaches the surface. When the cool air approaches the surface, it spreads out in all directions. High winds spread out in this type of pattern showing little or no curvature are known as straight line winds. Dry microbursts are typically produced by high based thunderstorms that contain little to no surface rainfall. They occur in environments characterized by a thermodynamic profile exhibiting an inverted V at thermal and moisture profile, as viewed on a Skew T log P thermodynamic diagram. Wakimoto (1985) developed a conceptual model (over the High Plains of the United States) of a dry microburst environment that comprised three important variables: mid level moisture, cloud base in the mid troposphere, and low surface relative humidity. These conditions evaporate the moisture from the air as it falls, cooling the air and making it fall faster because it is more dense.

Straight line winds (also known as plough winds, thundergusts, and hurricanes of the prairie) are very strong winds that can produce damage, demonstrating a lack of the rotational damage pattern associated with tornadoes. Straight line winds are common with the gust front of a thunderstorm or originate with a downburst from a thunderstorm. These events can cause considerable damage, even in the absence of a tornado. The winds can gust to and winds of or more can last for more than twenty minutes. In the United States, such straight line wind events are most common during the spring when instability is highest and weather fronts routinely cross the country. Straight line wind events in the form of derechos can take place throughout the eastern half of the U. S.

Straight line winds may be damaging to marine interests. Small ships, cutters and sailboats are at risk from this meteorological phenomenon.

The formation of a downburst starts with hail or large raindrops falling through drier air. Hailstones melt and raindrops evaporate, pulling latent heat from surrounding air and cooling it considerably. Cooler air has a higher density than the warmer air around it, so it sinks to the surface. As the cold air hits the ground or water it spreads out and a mesoscale front can be observed as a gust front. Areas under and immediately adjacent to the downburst are the areas which receive the highest winds and rainfall, if any is present. Also, because the rain cooled air is descending from the middle troposphere, a significant drop in temperatures is noticed. Due to interaction with the surface, the downburst quickly loses strength as it fans out and forms the distinctive "curl shape" that is commonly seen at the periphery of the microburst (see image). Downbursts usually last only a few minutes and then dissipate, except in the case of squall lines and derecho events. However, despite their short lifespan, microbursts are a serious hazard to aviation and property and can result in substantial damage to the area. Downbursts go through three stages in their cycle: the downburst, outburst, and cushion stages.

On June 21, 2023, a severe thunderstorm in the Greater Houston area resulted in a powerful downburst. The storm was part of a larger tornado outbreak sequence that occurred from June 20–26, 2023. A record breaking wind gust of 97 mph (156 km/h) was observed at George Bush Intercontinental Airport, surpassing the previous record of 82 mph (132 km/h) recorded during Hurricane Ike in 2008. The aftermath left approximately 324,000 customers without power and caused extensive damage to CenterPoint Energy's equipment and infrastructure. The storm caused significant damage to buildings, with at least 243 homes damaged. The storm was strong enough to flip a small plane and push another off the tarmac at Hooks Airport in northwest Harris County. On 21 May 2022, a particularly intense downburst was responsible for damage in Ottawa, Ontario, Canada. Maximum wind speeds reaching were surveyed and analyzed by the Northern Tornados Project, in an area measuring approximately 36 km (22 mi) long and 5 km (3 mi) wide. 10 people were killed and many communities experienced significant damage and power outages spanning days as a result of the derecho that moved across Ontario and Quebec. It was one of Canada's most destructive wind storms in its history, with over $875 million in damages across both provinces. On 31 March 2019, a very destructive downburst cluster with characteristics of a small derecho, but too small to satisfy the criteria, impacted across a wide and long swath in the Bara and Parsa Districts, Nepal. Occurring at an elevation of amsl around 18:45 local time, the 30 45 min duration winds flattened many and severely damaged numerous buildings, leading to 28 deaths and hundreds of injuries. On 15 May 2018, an extremely powerful front moved through the northeastern United States, specifically New York and Connecticut, causing significant damage. Nearly a half million people lost power and 5 people were killed. Winds were recorded in excess of and several tornadoes and macrobursts were confirmed by the NWS. On 3 April 2018, a wet microburst struck William P. Hobby Airport, Texas at 11:53 PM, causing an aircraft hangar to partially collapse. Six business jets (four stored in the hangar and two outside) were damaged. A severe thunderstorm warning was issued just seconds before the microburst struck. On 23 May 2017, a wet microburst struck Sealy, Texas with winds knocking down trees and power lines. Significant damage to structures was reported across Sealy. Twenty students were slightly injured by flying debris while attending a function at Sealy High School. On 9 August 2016, a wet microburst struck the city of Cleveland Heights, Ohio, an eastern suburb of Cleveland. The storm developed very quickly. Thunderstorms developed west of Cleveland at 9 PM, and the National Weather Service issued a severe thunderstorm warning at 9:55 PM. The storm had passed over Cuyahoga County by 10:20 PM. Lightning struck 10 times per minute over Cleveland Heights. More than 45,000 people lost power, with damage so severe that nearly 6,000 homes remained without power two days later. On 18 August 2011, a wet microburst hit the musical festival Pukkelpop in Hasselt, causing severe localized damage. Five people were killed and at least 140 people were injured. Later research showed that the wind reached speeds of On 22 September 2010, in the Hegewisch neighborhood of Chicago, a wet microburst hit, causing severe localized damage and localized power outages, including fallen tree impacts into at least four homes. No fatalities were reported. On 16 September 2010, just after 5:30 PM, a wet macroburst with winds of hit parts of Central Queens in New York City, causing extensive damage to trees, buildings, and vehicles in an area 8 miles long and 5 miles wide. Approximately 3,000 trees were knocked down by some reports. There was one fatality when a tree fell onto a car on the Grand Central Parkway. On 24 June 2010, shortly after 4:30 PM, a wet microburst hit the city of Charlottesville, Virginia. Field reports and damage assessments show that Charlottesville experienced numerous downbursts during the storm, with wind estimates at over In a matter of minutes, trees and downed power lines littered the roadways. A number of houses were hit by trees. Immediately after the storm, up to 60,000 Dominion Power customers in Charlottesville and surrounding Albemarle County were without power. On 11 June 2010, around 3:00 AM, a wet microburst hit a neighborhood in southwestern Sioux Falls, South Dakota. It caused major damage to four homes, all of which were occupied. No injuries were reported. Roofs were blown off of garages and walls were flattened by the estimated winds. The cost of repairs was thought to be $500,000 or more. On 2 May 2009, the lightweight steel and mesh building in Irving, Texas used for practice by the Dallas Cowboys football team was flattened by a microburst, according to the National Weather Service. On 12 March 2006, a microburst hit Lawrence, Kansas. 60 percent of the University of Kansas campus buildings sustained some form of damage from the storm. Preliminary estimates put the cost of repairs at between $6 million and $7 million. On 13 May 1989, a microburst with winds over hit Fort Hood, Texas. Over 200 U. S. Army helicopters were damaged. The storm damaged at least 20 percent of the fort's buildings, forcing 25 military families from their quarters. In a preliminary damage estimate, the Army said repairs to almost 200 helicopters would cost $585 million and repairs to buildings and other facilities about $15 million. On May 9, 1980, a microburst at the leading edge of an advancing cold front struck the 184.71 m freighter MV Summit Venture just as it was about to pass through the narrow channel under the Sunshine Skyway Bridge over Tampa Bay. Sudden torrential rain cut visibility to zero and straight line winds estimated at over pushed the ship into a support pier, causing the catastrophic collapse of the southbound span and 35 deaths as several private vehicles and a Greyhound Bus plummeted 45.72 m into the water. On 4 July 1977, the Independence Day Derecho of 1977 formed over west central Minnesota. As the derecho moved east southeast, it became very intense over central Minnesota around midday. From that time through the afternoon the system produced winds of 80 to more than , with areas of extreme damage from central Minnesota into northern Wisconsin. The derecho continued rapidly southeast before finally weakening over northern Ohio.