Atmosphere And Weather

Anatomy of a Super Cell



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Have you ever watched one of those apocalyptic movies where suddenly, the sky turns black, and a thick rolling cloud wall rips apart unleashing the ominous four horsemen. To a storm chaser or a meteorologist, it’s a rather fitting description of the awesome formation of a large supercell.

And, if every tempest was to have its maker, the supercell would have to be the grandmaster, producing some of the most devastatingly damaging storms. Supercells have the potential to deliver high-winds, severe down-pours, lightning, hail, micro-bursts, and down drafts—and, lest us not forget the extreme likelihood of the destructive force of a tornado.

Supercell and understanding storm formation.

To first understand the anatomy of a supercell, you need to know some of the basics about storm formations. Storms come in four types, single-cell, multi-cell cluster, multi-cell line, and supercells.

A storm (single-cell) by nature requires three basic ingredients: moisture (precipitation), unstable rising air mass, and something to force or lift the air.

First for this to happen, the sun begins to heat the earth, causing the lower layer of warmer air to rise. As this air rises, cooler, denser air falls below; this exchange is called convection, which in combination with moisture and unstable air masses, such as a strong jets-stream, can produce moderate to severe storm systems.

Most storms have a simple three stage life cycle: the developing or cumulus stage, the mature stage, where the storm is building and beginning to show lightning/thunder, and rain. Then, finally the dissipating stage, which is dominated by downdrafts as the moisture is dispelled.

 Most typical single cell systems have an average life cycle of 24 km, and lasts around 30 minutes.

Now, taking this model, we can now consider the second most important factor that defines a supercell storm system, which is rotation.

Rotation is produced by the fourth crucial ingredient, which is in the form of fast moving air, also known as wind shear. As hot air rises and cold air continues to mesh through convection, the catalyst, wind shear from the faster, cooler moving air in the upper atmosphere, clash with the slower, warmer air, thus forming the first signs of rotation.

What Makes These Bad Boys Tick:

Once this vertical wind shear keeps pushing vertically into this high/low pressure instability, the updraft pressure increases, and forms a mesocyclone or rotating updraft, which is also considered the vortex. At this point, the storm has developed into a supercell, which can be defined by its ability to create a repeating process, which unlike other storms can increase the longevity, travelling great distances before collapsing.

defined in three categories:

Rear Flanking – Low precipitation (LP), in these storms, like its name the updraft is located at the rear portion of the storm. Visibly, this may appear like a cork-screw like updraft, but can be difficult to discern, without the aid of something like Radar to identify the position of the vortex.

Classic (CL), More commonly, appear to have a large, flat updraft base, which has a wall cloud that may show precipitation banding around the boundary of the vortex. Usually, classic formations are typical to exhibit heavy precipitation and large hail-stones. Another unfortunate characteristic is the ability to produce large, long-lived tornadoes.

Front Flanking – High precipitation (HP), again the main updraft column will be positioned in the front of the storm, and will present itself with a large, sometimes obscured wall cloud. HP supercells can produce tornadoes, but are also associated to flash-flooding, and hail.

The anatomy of a super cell is in some ways, almost comparable to the affect that can occur if you place a drill in the center of a cup of water. The rotation can be increased with little change to the speed, but with a slight tilt, a vortex will form within the center axis. Sure water is not the same as air, and a drill does not bare any atmospheric pressure, but it does show how a tilted funnel can increase in both size and intensity. When this happens within the depths of a super cell, a deep rotating updraft or mesocyclone can continue to feed off the warm air that is layered over top of the cold air, which can prevent warmer surface air from dispelling far enough to disperse the instability that creates rotation near the base of the storm.

The Characteristics of a Super Cell: CLASSIFICATION)

- The precipitation area is the simplest term to understand, it obviously would be the region with the most moisture, or precipitation. This area lays between a precipitation-free-base and the precipitation striations that band around the updraft. A common trait found in a super cell is the increase or threshold of precipitation closer to the updraft.

- The wall cloud is formed close to the down, and updraft vortex, which is between the drier and less moist region of the cell, and the higher precipitation base. These walls are formed when rain cooled air from within the downdraft are sucked into the updraft. The wet, cold air sufficiently saturates as it rises again into the updraft, forming a cloud that could be described as though it was sinking. This characteristic is not a set descriptive for super-cells, and can occur in even less violent storm systems.

- Mammatus clouds are large fluffy puffs of cotton that billow from beneath the most violent part of these storms. The clouds are the conception of the cold air that descends into the warmer air beneath the funnel of the vortex.

- Precipitation-free-base, is highly likely to be found on the most southern side of the storm or the region, which sits fairly low below the main updraft (engine), and the main area of inflow. Like the name, there is barely any precipitation visible, but actually it can contain heavy downpours and onslaughts of large hailstones.

The most destructive system that are extremely likely to evolve from a supercell storm system is a tornado, but other severe conditions such as hail, damaging winds and lightning are expected. Isolated violent bursts of air called down bursts can certainly cause equal damage to that of a smaller class twister, but it is the tornado that still holds no opposition to describe the magnitude of destruction a supercell may possess.

Due to the increased advancements in satellite storm monitoring, coupled with a highly accurate Doppler system, super cells now can give us enough warning that we can sufficiently predict a impending tornado producing storm. There is still much more need for advance weather warning to ensure the safety of the public in such areas like Tornado Alley, but also so we can better understand the mystery, and maliciousness of a supercell!


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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.crh.noaa.gov/lmk/soo/docu/supercell.php
  • InfoBoxCallToAction ActionArrowhttp://www.nssl.noaa.gov/primer/tstorm/tst_basics.html
  • InfoBoxCallToAction ActionArrowhttp://www.srh.noaa.gov/srh/jetstream/tstorms/windshear.htm
  • InfoBoxCallToAction ActionArrowhttp://www.theweatherprediction.com/habyhints/42/
  • InfoBoxCallToAction ActionArrowhttp://www.usatoday.com/weather/wdoppler.htm
  • InfoBoxCallToAction ActionArrowhttp://www.crh.noaa.gov/lmk/?n=cloud_classification