Tornado : Southern United States
Over 20 people have died in the southern United States due to severe storms and tornado outbreaks affecting Missouri and Kentucky.
- A tornado is a vertical, land-based column of violently rotating air that forms from the base of a thunderstorm to the ground.
- It is characterised by a rapid cyclonic circulation and is often seen as a cloud-filled condensation funnel extending from the sky to the ground.
- In cases of low humidity, the tornado may not form a visible funnel and may appear only as a swirl of dust or debris near the ground.
- When such a rotating column of air forms over a water body, it is known as a waterspout.
- Tornadoes typically exhibit wind speeds ranging from 105 to 322 km/h, but some extreme events can exceed this range.
- They can be stationary or move at high speeds, often advancing at around 97 km/h across the landscape.
- The sheer speed and intensity of the winds make tornadoes one of the most destructive natural phenomena on land.
- Tornado formation is closely linked to interactions between contrasting air masses.
- A collision of warm, moist air (usually from tropical regions) with cool, dry air (typically from polar or upper regions), especially in the presence of a low-pressure system or trough, leads to the formation of thunderstorms and may trigger tornadoes.
- Cyclonic circulations and atmospheric instability further contribute to the rotational dynamics needed for tornado development.
- Tornadoes occur most commonly in mid-latitude regions (between 20° and 60° latitude in both hemispheres) where cold polar air meets warm tropical air, producing frequent thunderstorm activity.
- The United States experiences the highest frequency of tornadoes globally, particularly in the region known as “Tornado Alley”.
- Other countries prone to tornado occurrences include Argentina and Bangladesh, which also lie in the tropical-midlatitude interaction zones.
- The Enhanced Fujita Scale is used to classify the strength of tornadoes based on estimated wind speeds and associated damage levels.
