What is a mini tornado called?

Tornadoes: An Irish Perspective

We often receive e-mails or messages from members of the public inquiring about tornadoes or wondering if what they have witnessed could have been a tornado. In short, Ireland is not immune to tornadoes, and even if they are sometimes referred to as “mini-tornadoes”, they are still tornadoes. In fact, the term “mini-tornado” came into use to distance these tornadoes from the larger ones recorded in the U.S. and other countries. However, all tornadoes can be dangerous and on average there are 10 occurrences in Ireland each year.

Generally speaking, tornadoes are associated with the Mid-West or South of the United States, regions which are nicknamed Tornado Alley and Dixie Alley respectively. In these areas, very strong tornadoes mainly occur in spring and early summer, often causing tremendous damage and loss of life. Elsewhere, Bangladesh has a history of devastating tornadoes; the deadliest of these killed an estimated 1300 people in 1989. Due to poor infrastructure and warning systems Bangladesh accounts for five of the top ten deadliest tornadoes on record. In Europe approximately two to three hundred tornadoes per year were reported on average over the past few decades. The low countries, Germany, Southern Scandinavia, parts of Italy and Central England have the highest reported occurrences.

May 24th 2016, south of Dodge City, Kansas, U.S. Photo credit: Paul Downes.

In comparison, Ireland has had a relatively small number. The Irish tornado records include an interesting note on what was believed to be Ireland’s first documented tornado which occurred near Rosdalla, Kilbeggan, Co. Westmeath on the 30 th of April 1054 and is documented in the Annals of the Four Masters, Chronicon Scotorum.

Traditionally, supercells – a type of thunderstorm with a deep rotating updraft – are necessary to spawn the strongest tornadoes. Supercells are extremely rare in Ireland and thus landspouts (i.e. weak tornadoes not associated with a supercell) are more common. Landspouts are often generated along squall lines or associated with briefly energetic cumulus clouds. Funnel clouds also form in Ireland – those that do not come into contact with the ground or other surface are most common. Funnel clouds consisting of a violently rotating column of air, which is in contact with both the ground or surface and the base of the cloud, can be classified as tornadoes. Landspouts are often 20-100 m in diameter and have wind speeds of 60-180 km/h. In comparison, the widest tornado on record at 4 km wide occurred near El Reno Oklahoma in 2015 and the strongest on record, with wind speeds of 500 km/h, occurred in 1999 near Bridge Creek Oklahoma.

While summertime is marginally more conducive to the formation of tornadoes, the risk in Ireland, though low, spans throughout the year. Most tornadoes here are weak and brief and many occur without being noticed.

Research, Environment & Applications Division,

Tornadoes: An Irish Perspective

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  Cyclone vs. Tornado

  

  Cyclones and tornadoes are both stormy atmospheric systems that have the potential of causing destruction. They are caused due to instability in atmospheric conditions. According to the region and severity of stormy conditions, these storms may be referred to as typhoons, hurricanes, tropical cyclones and others.

  Comparison chart

  Cyclone versus Tornado comparison chart

  Cyclone	Tornado
  About	A cyclone is an atmospheric system of rapidly circulating air massed about a low-pressure center, usually accompanied by stormy often destructive weather. Storms that begin in the Southern Pacific are called cyclones.	A tornado is a rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud. Winds 40-300+ mph.
  Rotation	Clockwise in the southern hemisphere and counterclockwise in the northern hemisphere.	Clockwise in the southern hemisphere and counterclockwise in the northern hemisphere
  Intensity	Commonly quite strong. The scale for measuring cyclones is called the Beaufort Scale and Saffir-Simpson scale and may vary in different countries.Winds may approach 300kph and cause widespead damage.	The scale used for rating the strength of tornadoes is called the Fujita (F), Enhanced Fujita (EF), and TORRO (T) Scale.
  Location	Southern Pacific Ocean, Indian Ocean. Cyclones in the northwest Pacific that reach (exceed) 74 mph are «typhoons».	Tornados have been spotted in all continents except Antarctica.
  Most affected areas	Pacific Ocean	In areas where a convergence of cold and warm fronts is common. i.e. US Midwest.
  Frequency	10-14 per year	The United States records about 1200 tornadoes per year, whereas the Netherlands records the highest number of tornadoes per area compared to other countries. Tornadoes occur commonly in spring and the fall season and are less common in winters
  Occurrence	warm areas	Places where cold and warm fronts converge. Can be just almost anywhere.
  Forms of precipitation	rain	Rain, sleet, and hail

  Definition

  A cyclone is defined in the dictionary as «an atmospheric system characterized by the rapid inward circulation of air masses about a low-pressure center, usually accompanied by stormy often destructive weather».

  A tornado is defined in the dictionary as «a rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud». The wind speeds of tornadoes range from 40 mph to 110 mph, span about 75 m across and can travel a few miles. In extreme cases, tornadoes have also reached a speed of 300 mph.

  Geographical location

  Cyclones begin in tropical regions such as Pacific islands, Northern Australia and other areas.

  Tornadoes have been spotted in all continents except Antarctica. Highest frequencies occur in the Netherlands, and up to 1200 on average in the United States.

  Characteristics and types

  Cyclones have a low pressure center which is called the “eye”, and the wind circling around is counter clockwise on the northern hemisphere and clockwise in the southern hemisphere. Speed of cyclones varies from 32 to 200 kmph. Cyclones mainly occur in a particular season and mainly affect the coastal areas. Cyclones can be of six main types: polar, polar low, extratropical, subtropical, tropical and mesocyclones.

  There are many shapes and sizes of tornadoes. Tornadoes look like big funnels low in height with a cylindrical profile are referred to as “stovepipe” tornado, whereas those that are like large wedges stuck to the ground are called wedges. Tornadoes can also be a small swirl of dust close to the ground and not easily identifiable. Similarly tornadoes can assume twisted and rope-like shape that narrow and extends from the clouds down in a long and narrow tube like fashion; these are referred to as “rope tornado”. Tornadoes with more than one vortex can swirl around one common centre and appear as a single funnel. The types of tornadoes include multiple vortex, waterspout, gustnado, dare devil, fire whirls and steam devils.

  The color of tornadoes varies according to the region they occur in and depends on the color of the soil and debris collected. For instance, tornadoes with little debris appear gray or white, tornadoes in the Great Plain have a reddish hue because if the color of the soil, and tornadoes that occur in the mountainous snow-covered region turn white.

  Rotation

  Both cyclones and tornadoes turn clockwise in the Southern hemisphere and anticlockwise in the northern hemisphere.

  Intensity and Damage

  The scale for measuring cyclones is called the Beaufort Scale and Saffir-Simpson scale and may vary in different countries. The scale for measuring the intensity of cyclones depends on the intensity of damage and the wind speed. The scale ranges from negligible house damage, and destruction of plants and tress to extensive damage and widespread destruction, with wind speed ranging from 74 to 156 mph.

  The intensity of tornadoes can also vary in intensity those with a longer track being stronger. The scale used for rating the strength of tornadoes is called the Fujita (F), Enhanced Fujita (EF), and TORRO (T) Scale. The range varies from F0, EF0 or T0 for minimal damage (damages trees but not buildings) up to F5, EF5 or T11 for vast degree of damage (buildings and skyscrapers end up getting damaged).In the United States, maximum tornadoes (80%) fall into the EF0 and EF1 (T0 to T3) category and less than 1% are violent (EF4, T8 or more).

  Frequency

  There are 10-14 cyclones that occur per year.

  The United States records about 1200 tornadoes per year, whereas the Netherlands records the highest number of tornadoes per area compared to other countries. Other countries that have frequent occurrence of tornadoes include South Africa, Paraguay, parts of Argentina, and parts of Europe, Australia and New Zealand. Tornadoes occur commonly in spring and the fall season and are less common in winters.

  Detection

  Cyclones and tornadoes are detected by Pulse-Doppler radar, photogrametry, and ground swirl patterns.

  5 types of tornadoes

  The size of a tornado does not necessarily indicate its strength.

  By Jordan Smith Source FOX Weather

  

  5 types of tornadoes

  There are five types of tornadoes that you might see. Here’s what you need to know.

  Not all tornadoes are created equal. They vary in intensity, but they also vary in shape and size.

  According to the National Weather Service, there are five main types of tornadoes that you may encounter. Let’s take a dive into some tornado history and look at each type. Remember, the size of a tornado does not necessarily indicate its strength.

  Rope

  Rope tornadoes are usually the smallest kind of tornadoes and have a ropy, sinuous shape in their final minutes, but they can remain narrow during their entire lifespan. Although rope tornadoes may look weaker than much larger ones, some get more intense as they narrow and tighten.

  

  An example of a rope tornado.

  (NOAA)

  Cone

  Cone tornadoes are what everyone pictures when they hear the word «tornado.» They are wider at the base than rope tornadoes, and much wider where they meet the thunderstorm. This gives them a conical appearance. Because their footprint is wider, they can leave a larger trail of destruction.

  

  An example of a cone tornado.

  (NOAA)

  A «stovepipe» tornado is a cousin to the cone tornado. Its width at the ground and the base of the thunderstorm are similar, giving it a more cylindrical shape.

  

  An example of a «stovepipe» tornado.

  Wedge

  «Wedge» is slang for a large tornado that has a condensation funnel that is at least as wide at the ground as it is tall. The term is often used somewhat loosely to describe any large tornado, but not every large tornado is a wedge. A true wedge tornado is very rare.

  Wedges often appear with violent tornadoes, ranking EF-4 or EF-5 on the Enhanced Fujita Scale, but many documented wedges have been rated lower. Some violent tornadoes may not appear as wedges. However, according to the NWS, it generally is safe to assume that most wedges have the potential to produce major damage.

  Whether a tornado achieves wedge status depends on several factors other than intensity. In particular, meteorologists look at the height of the cloud base and the availability of moisture below the cloud base.

  

  An example of a wedge tornado.

  (NOAA)

  Multi-vortex

  Multi-vortex tornadoes are twisters in which two or more condensation funnels or debris clouds are present at the same time. They also often rotate around a common center or each other. These tornadoes can be especially damaging, according to the NWS.

  

  An example of a multi-vortex tornado.

  (NOAA)

  Waterspout

  A waterspout is a column of wind that rotates over a body of water. Despite its name, a waterspout is not filled with water. The visible column of wind that makes up a waterspout is created by condensation that occurs.

  Waterspouts can sometimes move ashore and cause damage. They usually dissipate quickly once moving onto land.

  According to the National Ocean Service, there are two types of waterspouts: tornadic and fair-weather.

  Tornadic waterspouts have the same characteristics as a tornado over land and are associated with severe thunderstorms. They often create rough water, large hail and lightning.

  Fair-weather waterspouts often form along the base of developing cumulus clouds and are not associated with thunderstorms. These waterspouts develop upward from the surface of the water and don’t usually move very much. This type of waterspout is near maturity by the time it is visible.

  

  Several waterspouts are seen in this image.

  (NOAA)