The tornado in Oklahoma earlier this week drew global attention due to its devastating power. So, what exactly is a tornado? How is a tornado formed?
Essential Facts About Tornadoes
What is a tornado?
According to meteorological dictionaries, a tornado is: “a violent, rotating column of air that extends from a cumulonimbus cloud to the ground, forming a funnel-shaped cloud that looks like a hose.”
In other words, for a vortex to be classified as a tornado, it must be in contact with both the ground and a cloud.
How do tornadoes form?
Tornado in Oklahoma
The classic and simplest answer is: “Warm, humid air from the Gulf meets cold, dry air from the mountains.” Many storms form under similar conditions but never come close to producing a tornado. This phenomenon is not yet fully understood. This is also why tornadoes do not occur in Vietnam as they do in Oklahoma.
According to Wikipedia, tornadoes develop from thunderstorms, typically from very strong or supercell storms, meaning wherever there are severe thunderstorms, there is potential for tornadoes, though they are quite rare. They can also originate from strong wind shear (known as gust fronts) or hurricanes. It is believed that when the air aloft is cold and presses down on the warm air below, the warm air is forced to rise strongly. However, when tornadoes occur over water, convection is often not observed, nor is there a significant temperature difference between layers. Thus, the causes of tornadoes remain partly enigmatic.
Nevertheless, most tornadoes are formed from a special type of thunderstorm known as a supercell. A supercell can last for several hours, rotate within an area with a diameter of 10 to 16 kilometers, travel hundreds of miles, and produce numerous large funnels. Their origin is in regions where warm air rises and cold air descends.
First, there is the interaction between the updraft of the storm and the winds. This interaction causes the warm air at the surface to rise and rotate in the atmosphere.
Next, cold air begins to move downward toward the ground on the opposite side of the storm. The speed of this descending air can exceed 160 km/h.
How long does a tornado last?
Tornadoes can last from a few seconds to over an hour. The longest tornado on record has not been established, as numerous tornadoes with long “lifespans” have been documented since the mid-20th century. Most tornadoes last less than 10 minutes.
The recent tornado in Oklahoma lasted over 40 minutes.
What is the Fujita scale?
Dr. T. Theodore Fujita developed a system to categorize tornado intensity based on the damage inflicted on structures due to wind speed.
The original F-scale is no longer in use, having been replaced by an improved version. The wind speeds associated with tornadoes remain somewhat of a mystery, and the wind speeds on the original F-scale were never scientifically tested or verified. This is because similar damage can result from different wind events, depending on the quality of the structures involved, wind direction, duration, and other factors.
The improved F-scale now rates tornado damage from F0 to F5 based on criteria such as buildings, trees, and structural integrity.
What does a tornado sound like?
The sound of a tornado depends on what it is attacking, its size, and whether it is strong or weak. The most common sound of a tornado is a continuous rumbling, similar to the sound of an oncoming train. Sometimes, a tornado can produce a loud noise like a waterfall or the sound of car windows shattering when the vehicle is moving at high speed.
