Hispano America

Severe weather is defined as any aspect of the weather that poses risks to life, property, or requires the intervention of authorities. Types of severe weather vary depending on latitude, altitude, topography, and atmospheric conditions. High winds, hail, and wild fires are some forms of severe weather which may be caused by thunderstorms, downbursts, lighting, tornadoes, and tropical cyclones;others are blizzards, snowstorms, and ice storms. According to the World Meteorological Organization (WMO) severe weather can be categorized into two groups: general severe weather and localized severe weather. (Wikipedia, October 2004 Severe Weather, 6-30-11 pgs 1-14)
Thunderstorms, also known as electrical storms, lightning storm, or simply a storm is a form of weather characterized by thepresence of lighting and its acoustic effect on the earth’s atmosphere known as thunder. This storm is usually accompanied by strong winds, heavy rain, and sometimes snow, sleet and hail. There are four types of thunderstorms: single cell, multi-cell cluster, multi-cell lines and super cells which are known to be the strongest most powerful type of thunderstorm. This type of storm can be very large,produce destructive tornadoes, winds of 80mph and produce extremely large hailstones (4”/10cm diameter). (Wikipedia, National Weather Services (4/21/05) Thunderstorm pg 1-20)
Thunderstorms have three stages of development. The initial stage is called the cumulus stage. During this stage warm, moist, and unstable air is lifted from the surface. As the air ascends, it cools and upon reaching its dewpoint temperature begins to condense into a cumulus cloud. Near the end of this stage, precipitation forms. During the second stage, mature stage, warm moist updrafts continue to feed the thunderstorm while cold down drifts (a product of the entrainment of cool, dry air into the cloud by the falling rain) begins to form.
As the rain falls through the air, it drags the cool, dry air thatsurrounds the cloud into it. As dry air comes in contact with cloud and rain droplets, they evaporate cooling the cloud. The final stage is the dissipating stage. When the thunderstorm dissolves away, the entrainment of cool air into the cloud helps stabilize the air, the surface no longer provides enough convective uplift to continue fueling the storm; as a result, the warm updrafts have ceased and onlythe cool down-drafts are down and as it ends the rain ceases and thunderstorms dissipate. (Wikipedia, Severe Weather, Thunderstorm, 7/11/11 pg 1-5)
Lighting is a massive discharge of electricity in response to a charge. The actual cause of lightning is not completely understood but it is known that lightning occurs in clouds that are located above the freezing level and are precipitating. Forlighting to occur, there must be a charge differential within a thunderstorm, between a thunderstorm and the ground or another cloud. Studies have shown that a charge transfer occurs across thin films of water present on ice crystals and hail stones when they collide; when they do collide in a cloud, some of the liquid-water molecules from the hailstone move to the ice. During this process there isa net transfer of positive charge from the hailstones to the ice and negative charges from the ice crystal to the hailstone. The accumulation of negative charge at the base of the cloud repels the negative charge on objects at the earth’s surface. Below the thunderstorm the earth’s surface attains a net positive charge. When the difference in charge is great enough, lightning is discharged.(Wikipedia, Severe Weather, Lighting, 7/11/11 pg 1)
A tornado is an intense system of low pressure with violent updrafts and converging winds. Tornadoes are spawned from severe thunderstorms. Winds are traveling at different speeds and from different directions, as the rotating air increases in height and shrinks in size a mesacyclone is formed.
A tornado can vary in diameter from a few hundred...