LITMIR.BIZ

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Devastating damage will occur: well‐built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes. 4 (major) 130–156 mph113–136 kt 209–251 km/h Catastrophic damage will occur: well‐built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months. 5 (major) 157 mph or higher137 kt or higher 252 km/h or higher Catastrophic damage will occur: a high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

       In 2008, Hurricane Ike affected Mississippi, Louisiana, and Texas. It killed nearly 200 people and resulted in over $37 billion in damages.

       “Superstorm Sandy,” as one of the largest hurricanes in history, made landfall north of Atlantic City in 2012 and decimated many buildings near the coast. The storm flooded subway stations in New York City and caused $65 billion in damages in many of the other northeastern states.

       In 2017, Hurricane Harvey pounded Texas and Louisiana, resulting in $125 billion in losses. That same year, Hurricane Maria impacted Puerto Rico with loss estimates over $90 billion.

       In August 2018, Hurricane Florence struck North Carolina and killed an estimated 3.4 chickens and 5,500 pigs. A month later, Hurricane Michael flattened structures in Mexico Beach, Panama City, and Port St. Joe with its 160 mph winds and 9‐ to 14‐foot storm surge. Hurricane Michael killed 16 people and produced $25 billion in losses.

      Hurricane Ida affected Louisiana in 2021. It caused serious devastation and resulted in 1 million people without power. The remnants produced major flooding in New York and New Jersey. Nearly 80 individuals died in the United States.

      Although the above storms were problematic, all of these hurricanes combined did not result as many deaths as a cyclone that hit Bangladesh in 1970. It tragically killed as many as 300,000 people and illustrated that hurricanes can be particularly devastating in developing nations.

      For Example

       The 2020 Hurricane Season

      The year 2020 was the most active hurricane season ever with 30 named storms and 13 major hurricanes. Twelve of these affected the continental United States with a 1–2 punch in Louisiana from Hurricanes Marco and Laura. These two storms were only separated by about 48 hours, which complicated response operations. While Marco was not as bad as anticipated, Laura produced 77 deaths and $19 billion in losses. Other storms, including Hurricane Sally, had major impacts on Alabama due to strong winds, storm surge flooding, and at least 20 inches of rain. The total amount of damage from the 2020 Hurricane season is estimated to be over $60 billion.

      A thunderstorm is another atmospheric hazard. Thunderstorms are produced when warm, moist air rises through convection (otherwise known as thermal uplift). These storms also occur along cold and warm fronts where different air masses collide or when clouds traverse mountain chains (i.e., orographic lifting). When a thunderstorm cell forms (with cumulus and cumulonimbus clouds), air rises and then descends quickly leading to rain, sometimes in copious amounts. This precipitation can lead to severe flooding and mudslides (which will be discussed further in sections 1.2.3 and 1.2.4).

      Depending on weather conditions and temperatures, the vertical movement of air also freezes water droplets that fall to the earth as hail. Most hail is small (e.g., pea size), but it can be larger at times (e.g., baseball or even grapefruit size). Hail can damage the roofs of buildings, destroy car windshields, and even kill those that are struck by it. Hailstorms can be costly natural disasters such as the one that hit Fort Worth, Texas, during a 1995 Mayfest celebration. The event resulted in at least $1 billion in losses. Over 100 people had to be taken to area hospitals after being struck by softball‐sized hailstones.

Thunderstorms also result in downdrafts and straight‐line winds (which travel down to the ground and then move horizontally along the earth’s surface). Such winds move quickly and can slam airplanes to the ground as was the case of USAir Flight 1016 on approach to the Charlotte‐Douglas International Airport in 1994. This crash resulted in 37 fatalities and injury to another 20 passengers. Downdrafts and straight‐line winds may also severely impact homes, barns, fences, etc. On August 10–11, 2020, a major and widespread windstorm (called a “derecho”) impacted several states including Wisconsin, Iowa, Nebraska, Illinois, and Indiana. Winds, ranging from 70 to 140 mph, created utility disruptions, decimated corn and soybean crops, and produced losses upwards of $11 billion dollars.

      Severe thunderstorms are not just common to the mid‐western portions of the United States. There are over 16,000 thunderstorms per year in all locations excluding the North and South Poles. Such storms also generate lightning, which is the emission of electrical bolts from clouds as a result of the interaction of positively and negatively charged fields. Approximately 6,000 lightning strikes occur every minute around the world. Lightning often hits buildings, trees and the ground. Homes and forests may be ignited with fire due to lightning. Because the temperature of the bolt is extremely hot (perhaps up to 50,000 degrees Celsius), people can be killed as well. Burns, respiratory failure, and cardiac arrest result from lightning strikes.

Tornadoes are another type of atmospheric hazard. Tornadoes are closely associated with thunderstorms. In fact, the name “tornado” stems from the Spanish name for such storms. As warm, moist air collides against cool, dry air, winds may move in a circular or rotating direction. One portion of the rotating air shaft drops, while the other portion moves upward in a vertical manner. If this air shaft touches down on lakes or oceans, it is known as a waterspout. When the resulting funnel reaches the ground, it becomes known as a tornado. The velocity of winds is the factor used to describe the strength of tornadoes under the Enhanced Fujita Scale. The Enhanced Fujita Scale is a scale used to categorize the size of a tornado, including the affiliated wind speed (see Table 1‐3). Small tornadoes (e.g., F0 or F1) are very common and possess slower wind speeds (e.g., 65 mph). Large tornadoes (e.g., F4 or F5) are infrequent, but their wind speed may reach over 200 mph. At such high speeds, windows are broken, roofs are ripped from walls, and even foundations can be sucked from their moorings. Glass, brick, two‐by‐fours, and even cars become projectiles and may penetrate other structures. The destruction from tornadoes can be extremely severe. For instance, the large F5 tornado that struck Joplin, Missouri in May 2011 became the costliest tornado in U.S. history. Damages in this disaster amounted to over $2.5 billion. St. John’s Regional Medical Center was one of the larger building structures that received extensive damage. Over 150 people were killed due to dangerous winds associated with this massive tornado.

Table 1‐3 Enhanced Fujita Scale for Tornado Damage.

      Source: National Oceanic and Atmospheric Administration, implemented in the U.S. on 1 February 2007. http://www.spc.noaa.gov/faq/tornado/ef‐scale.html.

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	Fujita scale	Derived EF scale	Operational EF scale