Crm Comuncation In dealing with weather there are many types which can seriously cause damage to people and communities. Especially in the aviation we as pilot have to take into account many consideration in preparing for a flight. For instance, thunderstorms, icing levels, winds aloft, and visibility all play major factors in preparing for a flight. But there are some weather phenomena that can be extremely dangerous to fly into. Hurricanes, wind shear, and tornadoes are just some of the major threatening systems that can cause serious damage to people and places.
One of the most interesting systems is the tornado. So what is a tornado? A tornado is a violently rotating column of air, which is found below cumulonimbus clouds and is nature’s most violent wind. A tornado is officially defined as an intense, rotating column of air extending from the base of a thunderstorm cloud to the ground. Wind speeds in tornadoes can vary from 72 to almost 300 mph. Fortunately, only 2 percent of all tornadoes have winds greater than 200 mph.
When a tornado is seen and has not yet made contact to the surface this is what is called a funnel cloud. When a funnel cloud touches the ground, it becomes a tornado (Jack Williams, USA TODAY Information Network). Most tornado’s range from 300 to 2,000 feet in diameters, but have been reported to extremes of one mile. Tornado’s usually travel in a southwest to northeast direction at about 30 knots in the U.S. According to Peter F.
Lester tornado’s lifetime average only for a few minutes, but have been documented to last over three hours. In the United States there is one particular place that seems to be more prominent to have tornado’s form. The American Meteorology Society’s Glossary of Weather and Climate defines Tornado Alley as: The area of the United States in which tornadoes are most frequent. It encompasses the great lowland areas of the Mississippi, the Ohio, and lower Missouri River Valleys. According to USA today Depending on the time of year, the southern and northern borders of tornado alley extend from about central Texas to Nebraska and Iowa. This region is where tornadoes spin up most frequently and where most monster, mile-wide twisters roam. The question is why is this area so prime for tornado’s to form? Thunderstorms thrive on lots of warm, humid air.
And the rotating thunderstorms, called supercells, which spawn the biggest tornadoes, need low-level winds that shift direction and grow stronger just above the ground (USA weather). The Gulf of Mexico provides an abundance of tropical moisture blowing into the Plains on south and southeast winds. Meanwhile the higher and drier elevations of the Rockies allow a hot, dry layer of air to blow over the region from the southwest. (USA TODAY Chris Cappella USA weathers source). It’s the unique combination of atmospheric parameters — a large moisture supply, low-level wind shear, a drying and cooling middle atmosphere, and features such as the dryline and a convective cap — that turn the Great Plains into a tornado alley.
The conditions responsible for the cause of tornado’s are basically wind from the west and moister that comes from the Gulf of Mexico. The clash of warm and cold air helps supply the humidity and energy needed. Winds from different directions high above the ground help supply more energy and also give the air the turning motion needed for tornadoes. The center of the tornado’s vortex is a low-pressure area. As air rushes into the vortex, its pressure lowers, which cools the air.
Cooling condenses water vapor in the air into the tornado’s familiar funnel-shaped cloud. Although the air is rising in a tornado, the funnel itself grows from the cloud toward the ground as the tornado is forming. Tornadoes form in the air rising into a thunderstorm, in the updraft. The strongest tornadoes are often near the edge of the updraft, not far from where air is descending from the thunderstorms. (Jack Williams, USA TODAY Information Network). Some times tornado’s can be mistaken for microburst.
The difference between microburst and tornado’s is that Air moves very rapidly upward around a tornado center. This distinguishes tornadoes from microburst, which often do tornado-like damage and are often mistaken for tornadoes. Microburst, on the other hand, features air blasting downward from thunderstorms. Since each tornado that is sprung has its own different strength there is a scale to measure the intensity of each one. A scale called the Fujita scale that was developed by T.
Theodore Fujita a professor at the University of Chicago measures the intensity of the tornado. The range of the scale starts at F0 which is a gale tornado with winds 40 to 72mph and cause damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards. The next level is F1 this is called a moderate tornado with winds ranging from 73 to 112mph; the damage caused ranges from peeling surfaces off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed. The next level is F2, which is classified as a significant tornado, with winds ranging from 113 to 157mph. This types causes Considerable damage roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.
A F3 tornado is classified as a sever tornado. This type of tornado has wind speeds of 158 to 206mph. The damage caused by these tornados’s are Roof and some walls torn off well constructed houses; trains overturned. F4 tornado’s are called devastating tornado’s. These have wind speeds of 207 to 260 mphs with damage of well-constructed houses leveled; structures with weak foundations blown off some distance and cars thrown.
F5 tornado’s have winds that reach between 261 and 318mph and are classified as incredible tornado’s. The damage these produce are Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-inforced concrete structures badly damaged. Most of the damage caused by tornado’s is due to the presence of one or more suction vortices. These are small, very intense funnels that rotate within the tornado itself. The last level of the Fujita Scale is F6 this is classified as an inconceivable tornado. At this level winds reach up to 319 to some manner of ground 379 mphs.
If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may through engineering studies. Many people think that the size of a tornado represents the intensity of it. Fujita Scale is based on damage, not the appearance of the funnel. So who does the actual surveying of the area of the tornado after it had passed? Personnel from the National Weather Service office that issued the warning survey the site to determine the F-Scale rating. Tornado’s just don’t form over land they have been to form over water. Tornados that form over water are usually weaker and are called waterspout.
In dealing with thunderstorms scientist have many ways to track and gather information about these systems. The researchers launched three to eight weather balloons into most storms and another three to eight balloons near the storms. These balloons transmitted a nearly continuous stream of meteorological information as they rise several thousand’s feet from the ground. One of these balloons caught air in one thunderstorm updraft rising at about 135 mph. The balloon data are important because temperatures, humidity levels and wind speeds and directions from the ground upward above 30,000 feet are key to determining which thunderstorms are most likely to produce tornadoes.
Other type’s of tracking devices that are used is Doppler radar. Doppler radar gives researchers a picture of wind movements inside storms. Such data is key to pinning down exactly what causes some thunderstorms to spin out twisters while other storms, that appear similar, produce hail, heavy rain and downbursts, but no tornadoes (National Oceanic and Atmospheric Administration). Aircraft are also used with the Doppler radar, which they fly into the storm and gather more data relating to the storm(National Oceanic and Atmospheric Administration). Other radar used is a new generation of radar call Nexrad.
Nexrad refers to the Next Generation Weather Radar’s the National Weather Service has installed around the U.S., which use the Doppler principle. All weather radar, including Nexrad, electronically convert the reflected radio waves into pictures showing the location and intensity of precipitation. The new radar’s today rely on computers very much to interpret the weather around us. The computers today actually can be programmed to give heads up notice to weather patterns that appear to be dangerous, compared to older models that someone had to watch the screen all the time and make that determination by himself or herself. Bibliography REFERENCES Edwards, Roger Storm Prediction Center 22 Sep 2000 www.spc.noaa.gov/faq/tornado/ Golden, Joseph NOAA/OAR/USWRP Silver Spring MD www.esig.ucar.edu/socasp/weather/ NSSL Tornado Information www.nssl.noaa.gov/edu/tornado The Weather Channel Homepage/Tornado Climatology www.weather.com Bluestein, H.
B. and C.R Parks, 1983: A synoptic and photographic climatology of low precipitation severe thunderstorms in the Southern Plains. Brandes, E A. 1993: Tornadic thunderstorm characteristics determined with Doppler Radar.