Camera records downburst in the United States

A downburst was recorded by television cameras as it occurred last week in Wake County, North Carolina. The images were taken by the camera installed in the tower of the television station. WRAL and recorded the violent downdraft of wind accompanied by rain, a phenomenon of an isolated character and virtually impossible to predict exactly which zone it will hit.

This type of phenomenon occurs mainly in the summer because it is the time when the days are very hot and, under the presence of high humidity, clouds of great vertical development of the Cumulonimbus (Cb) type are formed, which can reach up to 15 to 20 kilometers. in height and are capable of generating destructive wind. That’s what caused much damage in the municipality of Guaíba last January.

On its website, the National Weather Service from the United States explains what a downburst is – a violent downdraft of wind – which is capable of producing damage and damage as severe as that of a tornado due to the enormous speed that the wind can reach during episodes of this type of phenomenon.

“A downburst is a strong and relatively small area of ​​rapidly descending air under a storm that can result from very strong wind at altitude being carried to the surface. Or it could be the effect of the very rapid cooling of the air with the rain that evaporates in an initially dry atmosphere. The cooler, denser air quickly descends to the surface.

A downburst differs from an ordinary storm wind by its potential to cause damage near the surface, where it spreads or diverges considerably. In contrast, in tornadoes they converge on a narrow strip of terrain.

Intense downbursts can be phenomenal. Wind speeds can reach marks as high as those observed at 281 km/h in Morehead City (North Carolina) and 254 km/h at Andrews Air Force Base (Maryland). Severe episodes of downburst can cause sounds and noises that people often refer to as being from a freight train, a term typically associated with tornadoes.

Although downbursts are not tornadoes, they can cause damage equivalent to that of a small or medium tornado, after all, wind is wind. Downbursts are classified as either macrobursts or microbursts, depending on the extent of the area affected by the wind. Damage from macrobursts extends horizontally for more than four kilometers while in microbusts the destructive winds occur in an area of ​​less than four kilometers.”

A Cumulonimbus cloud, due to its violent updrafts and downdrafts, inside and next to the cloud, generates strong to severe turbulence, hail, ice formation, lightning and sometimes tornadoes, which is a risk for aircraft mainly during landing and take-off before the danger of wind shears and violent downdrafts (microburst).

After several air accidents caused by downward currents (downbursts) in the United States, airports started to have meteorological radars and several studies were carried out in the country.

The most famous case is the Delta Flight 191 disaster in which 137 people died. The aircraft was preparing to land at Dallas airport when it was hit by a microburst, an intense downdraft in a storm cloud, and the plane was caused to crash into the ground a kilometer from the runway.

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