Tornado and Hurricane formation processes - Research Paper Example

Tornado and Hurricane formation processes Abstract The introductory part of the paper gives a general overview of the effects of tornadoes in the United States of America by citing the worst hit years. The second part of the discussion explicates the tornado formation processes. Consequently, a discussion of the effects of hurricane as well as the formation processes is discussed on the last chapter of this paper. Introduction The United States of America has had an experience of the World’s deadliest tornadoes between 1925- 2011. A deadly tornado occurred in 18th March, 1925 which affected three towns (The Tri-State). The disastrous tornado began in Missouri and stayed on the ground for about 220 miles moving at a super speed to Illinois and Extending to Indiana (The tornado project 2012) The tornado left a trail on its passage measuring approximately 1.6 kilometers in width. Approximately six hundred and ninety eight persons lost their lives whereas two thousand people experienced injuries. (The tornado project 2012) On 14th April, 2011 a series of deadly tornadoes hit the Southern United States devastating the Cities of Oklahoma to Northern Carolina where dozens of people lost their lives and property (The tornado project 2012) The tornado formation process According to Weisman et al 1982, concur that majority of violent tornadoes are spawned by Supercells storms; these storms undergo an average rotational movement (cyclonic in nature) with the highest vorticity almost coincident with the updraft core. The average rotational movement is referred as the mesocyclone. Supercells are always developed in extremely high convectible existing potential energy characterized by warm, moist air within the PBL and a lot of cool air aloft; large winds shear as well as convectible inhibition. Other factors responsible for the formation of Supercells may include the availability of dry air within the troposphere. This may be directed into the storm, cooled by an evaporative cooling in within the mixed air parcel. This condition leads to the development of the down draft. Strong down drafts implies strong updrafts as well as more severe storms (Weisman et al 1982) There are other three mechanisms that lead to the formation of strong tornadoes: The presence of mesocyclone with an average diametrical measurement of 15-20 km. The circulation process is at least a dimension of magnitude larger than the tornado itself. However, near the ground the mesocyclone can be eliminated by the updraft a process referred as the vortex stretching. It increases the magnitude of the circulation as a result of angular momentum conservation. A continuation of the stretching leads to the development of a narrow funnel which can be observed due to low core pressure. A diabatic expansion results into cooling which triggers condensation hence the droplets of the clouds develops a visible funnel (Weisman et al 1982) Another mechanism is the tilting of the rotation around the horizontal axis, the horizontal vorticity resulting from the vertical shear of the wind in the storm environment. Majority of supercell storms develop in sheared environments with poleward wind almost at the ground and strong westerly winds aloft. The horizontal vortex is tilted as the air begins to rise within storm’s updraft leading to creation of a component of spin about the vertical axis. Vertical vorticity as a result of horizontal tilting is always intensified more by vortex stretching. The wind shear that develops the horizontal vorticity can be triggered by the storm (Weisman et al 1982) Consequently, a cold pool developing under the mature severer storms could lead to formation of violent tornadoes. Evaporation of rain water below the cloud as well as a result of an average entrainment of air characterized by much lower equivalent potential temperatures than the surface causes the development of a cold pool below the cloud. A boundary is formed between the cold pool and warm moist inflow known as the gust front. Horizontal vorticity is formed by temperature gradient along the gust front. The baroclinically developed vorticity is moved into the main updraft by a low level inflow into the gust front, and the vorticity movement spins along the updraft (Weisman et al 1982) Hurricanes Hurricanes are experienced throughout the world mostly on the Atlantic and Pacific Oceans and are called by different names depending on where it occurs. Within the Pacific and the Atlantic Oceans, they are referred as the hurricanes while in the Southern Pacific they are referred as the Cyclones (WTVY 2002) In other pacific regions, they are called typhoons. Hurricanes have had significant negative impacts on the environment as well as on human well-being. A case of the disastrous nature of the hurricanes has been of observed in the Haiti on August 2008 where hurricane hit the Central Plateau Region submerging several homesteads as well as death of dozens of people. Property worth million dollars were also lost (WTVY 2002) The Hurricane formation process Tropical cyclones develop over warm waters from initially existing disruptions. The disruptions always develop every three to four days from the African coasts as tropical waves that are made of unsettled weather. This leads to development of storm which subsequently develops into a mature hurricane (WTVY 2002) The subsequent processes that lead to the formation of the cyclone and eventually the hurricane are distinctive of: Stage one: (Tropical wave) a disturbance is exhibited in the normal tropical easterly wind flow; ascribed turning of wind which results to low level of convergence air. This process leads to reduction of pressure as well as enhanced showers Heat and energy for the storm collects together as a result of disruptions through contact on the warm ocean waters (WTVY 2002) Stage two: (Depression stage) during these early processes, he system is visible on the satellite image as an almost disorganized collection of thunderstorms. Favorable weather as well as ocean conditions may strengthen this process hence developing into a depression (wind with less than 38 mph) the winds next to the ocean surface spirally advects into the disrupted low pressure zone. Warm ocean waters create moisture as well as heat to the air which rises. Condensation of the moisture into droplets leads to the release of more heat contributing to more energy which powers the storm (WTVY 2002) The third stage known as the tropical storm involves the sustained winds approaching an average speed of 39 mph in the closed circulation tropical storm. Bands of thunderstorms are developed and the cloud top of the storm rises higher into the atmosphere. The storm may remain undisrupted and strengthen when atmospheric winds remain relatively light (WTVY 2002) Consequently, a hurricane is developed when the storm begins to form a spiral appearance as a result of flow winds as well as the rotation of the earth. Bands of thunderstorm contribute more heat and moisture to the storm as it strengthens. The storm develops into hurricane when winds reach a minimum of 74 mph. At this moment, the cloud free hurricane eye develops due to rapidly sinking air at the middle dries and warms the zone (WTVY 2002) A mature hurricane is ultimately formed moving at an average speed of 15-20 mph and can accelerate up to 60 mph (WTVY 2002) A picture showing the aerial view of a mature hurricane moving horizontally at an approximate speed of 60 mph References Top Ten US Killer Tornadoes. The Tornado Project Online! Retrieved May 17, 2012, from http://www.tornadoproject.com/toptens/toptens.htm Weisman, M.L. and Klemp.J. (1982).The Dependence of Numerically Simulated Convective Storms on Vertical wind Shear and Buoyancy. Mon. Wea. Rev., 110, 504-520. Hurricane Formation and Anatomy.WTVY: Homepage. Retrieved May 15, 2012, from http://www.wtvy.com/hurricane/misc/19523219.html Read More