Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Taking Severe Weather Seriously Kathy Johnston, Science Teacher North Middle School Lenoir City, TN Dangerous weather develops in an instant and may occur at any location on Earth. Severe weather conditions can range from high winds to hurricanes, from heavy rain to floods, or from snowfall to blizzards. By discussing the various types of severe weather, we better prepare ourselves in the event of a weather disaster. Thunderstorms Thunderstorms, tornadoes and lightning are the most violent types of severe weather. A thunderstorm is formed when moist air rises and cools to its dew point. The cooling, moist air condenses forming clouds. The colder, heavier air begins to sink forming downdrafts with the resulting precipitation. Thunderstorms are classified into four types – single cell, multicell, squall line, and super cell. Single cell storms are rare since even the weakest of storms usually occur as multicell updraft events. Some single cell thunderstorms are called "air mass" storms. These storms usually last only 20 to 30 minutes and generally do not generate severe weather. However, one must remember that any thunderstorm is capable of producing a tornado. Most thunderstorms are multicell storms lasting several hours. Storms of this type are capable of producing large hail, damaging winds, flash floods, and isolated tornadoes. When thunderstorms form in a line, they are called squall lines. These storms usually generate damaging winds and dangerously large hail. Tornadoes may be present with squall line storms; however, they are usually weak and short-lived. Most wind damage from squall line storms is caused by extremely strong downbursts. The rarest and most dangerous type of thunderstorm is the supercell. Fortunately, they are the easiest to forecast and track by radar. The deep rotating updraft can be identified on Doppler radar as an intense orange or red. www.WeatherBugSchools.com Lightning Lightning is the most frequent and most dangerous type of weather phenomena. Although it affects the entire United States, the states that have the most injuries and deaths are Florida, Michigan, Pennsylvania, North Carolina, New York, Ohio, Texas, Tennessee, Georgia and Colorado. The almost continual occurrence of lightning strikes is amazing. There are approximately 100 lightning strikes per second on the Earth. That is 8 million, 6 hundred and 40 thousand times per day! In the United States alone, the damage from lightning can be over four million dollars per year. What is lightning? Essentially it is a form of electrical discharge that results from the buildup and release of electrical energy between positively and negatively charged portions of a cloud. It can strike inside a cloud from several sections of the cloud, from cloud to cloud or from cloud to ground. One flash of lightning has enough power inside to run a 100-watt light bulb for over three months. The air surrounding the lightning strike is hotter than the surface of the Sun! Thunder occurs inside the cloud at the same moment as the lightning strike, but because light travels almost a million times faster than sound, we see the lightning before we hear the thunder. Although it travels slowly, the sound of thunder can be heard up to twelve miles from the actual thunderstorm. Also lightning can strike as much as 12 miles ahead of a storm. People are encouraged to follow precautions when lightning is spotted. If caught in the open, a person should crouch down into a ball-like position with the feet on the ground. Lying down is not an effective method of avoiding a lightning strike. www.WeatherBugSchools.com The lower part of a thundercloud is usually negatively charged. The upward area is usually positively charged. Lightning from the negatively charged area of the cloud generally carries a negative charge to Earth and is called a negative flash. A discharge from a positively-charged area to Earth produces a positive flash. - (NOAA) www.WeatherBugSchools.com Tornadoes The tornado is nature’s most violent storm. It may contain wind speeds of two hundred and fifty miles an hour or more and can last from one minute to an hour. The fear of tornadoes can keep children awake at night and make anyone tremble with fear. Tornadoes are indeed fearsome and deserve every ounce of concern if the possibility of their formation is indicated. Through scientific research and weather data analysis, the warning systems for severe weather have improved tremendously in the past two decades. Doppler radar images give us minute by minute tracking of serious weather happenings. Lightning detection systems inform us of the potential for deadly strikes. Computerized models enable meteorologists to track weather systems and alert areas of possible thunderstorms up to a week in advance. These systems are in place for our information and safety. They are easily available through various media. It is up to us to take severe weather seriously. Tornadoes will be the topic of next month’s Connections. Create a Severe Weather Plan for your School Objectives: Investigate severe weather safety Identify needs during a severe weather event Determine a classroom plan Compare with other classroom and school level plans Use the Tornado Safety (http://www.spc.noaa.gov/faq/tornado/safety.html) information page as resource. Remember the big questions when putting together a plan are what, where and when. Only then can you make a reasonable plan. What type of severe weather? Where is it going? When is it expected to strike? www.WeatherBugSchools.com