Thunderstorms - SeventhScience / FrontPageseventhscience.pbworks.com/w/file/fetch/88274045/severe...
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severe weather.notebook 1 November 06, 2014 May 710:31 PM A thunderstorm is a storm with lightning and thunder. It's produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. A typical thunderstorm is 15 miles in diameter and lasts an average of 30 minutes. Thunderstorms can happen, at any time of year, and any time of day. But, they are most likely to happen in the spring and summer months and during the afternoon and evening hours. There are an estimated 1,800 thunderstorms that occur across our planet every day. Thunderstorms May 710:31 PM thunderstorms The basic ingredients used to make a thunderstorm are: 1) moisture to form clouds and rain 2) unstable air relatively warm air that can rise rapidly, and 3) lift fronts, sea breezes and mountains are capable of lifting air to help form thunderstorms. Thunderstorm Recipe
Transcript of Thunderstorms - SeventhScience / FrontPageseventhscience.pbworks.com/w/file/fetch/88274045/severe...
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A thunderstorm is a storm with lightning and thunder. It's produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. A typical thunderstorm is 15 miles in diameter and lasts an average of 30 minutes.
Thunderstorms can happen, at any time of year, and any time of day. But, they are most likely to happen in the spring and summer months and during the afternoon and evening hours. There are an estimated 1,800 thunderstorms that occur across our planet every day.
Thunderstorms
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thunderstorms
The basic ingredients used to make a thunderstorm are:1) moisture to form clouds and rain2) unstable air relatively warm air that can rise rapidly, and 3) lift fronts, sea breezes and mountains are capable of lifting air to help form thunderstorms.
Thunderstorm Recipe
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The National Weather Service (NWS) declares that a thunderstorm is severe if: wind gusts reach 57.5 mph or faster hail is 3/4 inch in diameter or bigger, OR the thunderstorm produces a tornado or tornadoes.
Air that's moving up, called an updraft, feeds warm, humid air into a thunderstorm. Some updrafts can reach speeds of 40 mph or faster. These updrafts carry a huge amount of air up, which means large amounts of air are going to be coming down (downdrafts). Normally, a thunderstorm has both updrafts and downdrafts.
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Downdrafts in severe thunderstorms can create gusty winds as high as 160 mph. Downdraft winds can smash buildings, uproot trees, and are often mistaken for tornadoes. If the downdraft is concentrated in an area less than 2.5 miles in diameter, it is called a microburst.
Thunderstorm Dangers
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Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher until they freeze into ice. Once they become heavy, they will start to fall. If the smaller hailstones get caught in the updraft again, they will get more water on them and get lifted higher in the sky and get bigger. Once they get lifted again, they freeze and fall. This happens over and over again until the hailstone is too heavy and then falls to the ground.
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All thunderstorms are dangerous, because every thunderstorm produces lightning. Lightning can strike people and buildings, and kills more people each year than tornadoes. Heavy rain from thunderstorms can also lead to flash flooding. Strong winds, hail, and tornadoes are other dangers associated with some thunderstorms.
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Severe Thunderstorm Watch A severe thunderstorm (damaging winds of 58 miles per hour or more, or hail 3/4 of an inch in diameter or greater) is likely to develop in your area.
Severe Thunderstorm Warning A severe thunderstorm (damaging winds of 58 miles per hour or more, or hail 3/4 of an inch in diameter or greater) is taking place in your area.
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Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it opens up a channel in the air. Once then light is gone, the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!
You can estimate how many miles away a storm is by counting the number of seconds between the flash of lightning and the clap of thunder. Divide the number of seconds by five to get the distance in miles.
Lightning
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Lightning is an electric current produced by a thunderstorm. High in the thundercloud, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge which eventually fills the cloud.
The positive charges form at the top of the cloud and the negative charges form at the bottom of the cloud. Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The ground's electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds.
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lightning
Roy Cleveland Sullivan was a park ranger in Shenandoah National Park in Virginia. Between 1942 and 1977, Sullivan was hit by lightning seven times and survived! He is recognized by Guinness World Records as the person struck by lightning more recorded times than any other human being. He died from a selfinflicted gunshot wound at the age of 71 over an unrequited love.
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* The average lightning bolt is about an inch wide and five miles long, although the longest lightning bolt was 118 miles.
* Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.
* Your chances today of being struck by lightning is about 1 in 3,000 (better odds than winning the lottery).
* The temperature of lightning is approximately 55,000 degrees, which is hot enough to fuse sand into glass!
* Yes, lightning can strike the same place twice the Empire State Building in New York City is struck an average of 25 times a year.
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* When a flash of lightning is seen, but no thunder is heard, this "heat lightning" is actually from a storm that is too far away to be heard. Since sound waves are bent and dispersed as they travel through the air, thunder is typically heard from storms that are closer than 10 miles, though, under the right conditions, storms can be heard as far as 20 miles away.
* Lightning comes from a parent thunderstorm, but the storm can sometimes be more than 25 miles away from the lightning strike. So, if you can hear the thunder, you are in range of a lightning bolt.
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TornadosA tornado is "a violently rotating column of air in contact with the ground and coming from a thunderstorm." Tornadoes are the most violent storms on Earth. Winds spiraling into them are usually over 100 mph and can reach speeds of 300 mph. In the USA, an average of 1,000 tornadoes occurs each year, and typically kill about 60 people.
Tornadoes can occur any time of the year, during the day and at night, but spring is the most favorable time. More tornadoes hit the US than any other country in the world.
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Tornadoes form within a thunderstorm's updraft. Changing wind speeds and directions in the thunderstorm create a spinning column of air in the middle of the thunderstorm. If the spinning column develops in the bottom of the storm, the funnel cloud can touch down to the ground, and is called a tornado.
The strongest tornadoes are often near the edge of the updraft, not far from where there is a downdraft caused by thunderstorms with falling rain or hail. This is why a burst of heavy rain or hail sometimes signals a coming tornado.
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Most weak tornadoes last 10 minutes or less, traveling short distances. Violent tornadoes have been known to last for hours and a few have traveled more than 100 miles.
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Tornadoes have occurred in all 50 U.S. states and are often seen in the middle part of the United States in a 10state area stretching from Texas to Nebraska that also includes Colorado, Iowa, Illinois, Indiana, Missouri and Arkansas, known as Tornado Alley.
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Tornadoes are ranked by the damage they do using the Fujita Scale. F0 and F1 tornadoes on the scale are considered "weak" and cause minimal to moderate damage. F2 and F3 tornadoes are considered "strong" and cause major to severe damage. "Violent" tornadoes are those classified F4 and F5 with extreme to catastrophic damage.
The ratings are: EF0. Light damageWind 65 to 85 mph. Peels surface off some roofs; some damage to gutters or siding; branches broken off trees; shallowrooted trees pushed over.
The scale was enhanced in 2007, with rankings running from EF (Enhanced Fujita) 0 through 5. The ratings are based on the amount and type of wind damage.
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EF1. Moderate damageWind 86 to 110 mph. Considerable roof damage. Winds can uproot trees and overturn singlewide mobile homes. Flagpoles bend.
EF2. Considerable damageWind 111 to 135 mph. Most singlewide mobile homes destroyed. Permanent homes can shift off foundation. Flagpoles collapse. Softwood trees debarked.
EF3. Severe damageWind 136 to 165 mph. Hardwood trees debarked. All but small portions of houses destroyed.
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EF4. Devastating damageWind 166 to 200 mph. Complete destruction of wellbuilt residences, large sections of school buildings.
EF5. Incredible damageWind above 200 mph. Strong frame houses leveled off foundations and swept away; automobilesized missiles fly through the air in excess of 100 m (109 yd); steel reinforced concrete structure badly damaged; highrise buildings have significant structural deformation.
So far there have been fourteen EF5 tornadoes recorded since the Enhanced Fujita Scale was introduced on February 1, 2007. The most recent one occurred in El Reno, OK on May 31, 2013. The tornado measured 2.6 miles wide, and had winds of 295 mph. and leveled half the city.
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Tornado SafetyA Tornado Watch means conditions are right for possible tornados.
A Tornado Warning means a tornado has been spotted by radar or by a person.
If you are inside, your safest place is a basement, or an interior room or closet in the middle of the bottom floor.
Outside, never try to outdrive a tornado. Lie in a ditch or lowlying area and protect your head and neck.
Taking shelter under a bridge is not a good idea. Winds accelerate under an overpass, and the tornado can throw debris at you.
tornadoes
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Vortex 2 video of Wyoming tornado:Tornado Caught Live
Vortex 2 was an effort made by scientists to understand tornadoes in May and June of 2009 and 2010. They were sponsored by the National Science Foundation and the National Oceanic and Atmospheric Administration (NOAA) and attempted to collect data in order to better forecast tornadoes (think like in the movie "Twister," but without actually getting caught in the tornado). Participants were/are scientists and college students and traveled throughout the Plains states.
