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Unit 4 - Weather

Unit 4 - Weather. What Causes Severe Weather?. Thunderstorms. Thunderstorms are another severe rain weather threat. They carry with them the danger of lightning strikes and can knock out electric power and down trees and they also may create flash floods.

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Unit 4 - Weather

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  1. Unit 4 - Weather

  2. What Causes Severe Weather?

  3. Thunderstorms • Thunderstorms are another severe rain weather threat. They carry with them the danger of lightning strikes and can knock out electric power and down trees and they also may create flash floods. • Flash floods move quickly and can carry rocks and debris. Slow flooding occurs as rivers and lakes rise with great rainfall amounts.

  4. Their Cloud Formations • Cumulus Stage first stage of cloud development as warm humid air rises and water vapor condenses to form a cloud • Mature Stage when a cloud reaches maximum vertical development precipitation starts to fall and the most violent weather such as lighting occurs. • Dissipating Stage stage where a down draft occurs in the cloud and it sinks and evaporates away

  5. Hurricanes - Hurricanes can span hundreds of miles and do massive amounts of damage. Most hurricanes that strike the U.S. begin over the Atlantic ocean. Where they make landfall can be estimated but never guaranteed. Freezing Weather - Extreme cold carries serious dangers. When temperatures drop far below the freezing mark of 32 degrees Fahrenheit, prolonged exposure can mean frostbite, hypothermia and even the loss of extremities. Snow storms and blizzards can cripple an area by closing roads and businesses and knocking out power.

  6. Drought • When temps soar above 90 or 100 degrees Fahrenheit, overexposure to this type of heat can dehydrate the body and tax its organs beyond their limits. • In already dry climates, a spell of severe heat can cause a drought. Droughts can destroy crops and limit a community's water supply.

  7. So What Causes All of This? • GLOBAL WARMING!!! Jk. However, it does play a big factor. • The main forces behind these disasters have been natural weather cycles, such as back-to-back La Niñas in 2010 and 2011 that routed storms away from drought-prone parts of North America, and a massive high pressure system, known as a heat ridge, that parked itself over the U.S. this summer and refused to budge.

  8. So What Causes All of This? • Since 1970, the average global temperature has risen by 0.9°F (0.5°C), primarily as a result of greenhouse gases in the atmosphere, according to most scientists. This additional heat has increased the chances for severe heat waves, drought, and other forms of extreme weather.

  9. Video • http://www.discovery.com/video-topics/other/extreme-weather.htm

  10. Tornados

  11. How are tornados formed?

  12. What are they? Tornadoes are caused by conflicting air currents of hot air and cold air travelling in opposite directions creating a cyclone from thunder clouds called super cells.

  13. How are they measured? The strength or force of a tornado is measured on the Fujita-Pearson Tornado Scale.  According to the National Weather Service, F6 is the highest category of tornado, with winds capable of 261-318 mph. The tornadoes are ranked from the weakest F1, to the strongest ever recorded an F6.

  14. What are they capable of? 7 in 10 tornadoes are categorized as weak, these are small rope –like and violent, lasting only 15 minutes most houses survive a direct hit. The typical funnel shaped tornadoes are stronger but only 3 in 10 occur, these are capable of leveling only the smaller houses and don’t reach 200 mph rotation Finally only 5% of tornadoes are the strongest capable of wiping out the strongest of the houses, these are the F5 F6s with wall clouds caused.

  15. Where do they occur? “Tornado Alley,” as it is called stretches, the mid-west plains of America. This is due in part to the hot air of the plains clashing with the cold dry air of the mountains to the east and west. More tornadoes occur in this area than anywhere else about 1200

  16. How do they track tornadoes? Skywarn is an organization consisting of individual tornado spotters. During severe thunderstorm situations, the spotters closely monitor the skies for tornado development. With mobile weather radar, dual-polarized Doppler radar and National Weather Radar Testbed, predictions, and warnings of high-impact weather including tornadoes, severe thunderstorms, and flash floodsare better known and tracked

  17. Video http://video.nationalgeographic.com/video/environment/environment-natural-disasters/tornadoes/inside-the-tornado/

  18. How do meteorologists predict the weather?

  19. Meteorologist use soil, ocean, atmosphere temperatures, and analog years as a few of their ways to predict the weather. Analog year - a past year where there were similar temperatures in the ocean and pressures in the atmosphere to the current conditions.

  20. Pacific Ocean temperatures are a key factor in forecasting weather patterns. La Niña - occurs when sea surface temperatures across the equatorial central and eastern Pacific are below normal. El Niño - occurs when the sea surface temperatures across the equatorial central and eastern Pacific are above normal.

  21. Meteorologists watch temperature, dew point, winds, and upper level winds to predict the weather more accurately. Although, The conditions of the atmosphere and the oceans consistently change making it harder for Meteorologists to be more accurate when predicting the weather

  22. Long-range forecasters study recent trends in the weather, looking at temperature, rainfall, drought, snow cover and more. Long Range Forecasts - A forecast that is more than one round/week into the future.

  23. Computers help guide the precision of forecasting the weather but experience is still one of the best teachers. Humans have a major impact on the weather - Trapped radiation or not getting radiation from the sun due to pollution. http://www.youtube.com/watch?v=IJSDxjnlHYc

  24. How have forecasters improved at predicting the weather?

  25. Grid Points Satellites over large areas of the globe that calculate what the atmosphere will do.

  26. Weather Balloons Twice a day, 1,100 balloons are sent across the Earth to record temperatures, humidity, air pressure and wind.

  27. Computers Advanced computers now help with different weather equations that are said to be more complex than aerodynamics equations.

  28. Radars, Doppler’s and Spaghetti Plots Radars show precipitation Doppler’s can predict possible tornados Spaghetti Plots are lines drawn across a map demonstrating weather changes up to 10 ½ days.

  29. 1959 Operational Manual Recent national weather laws prohibited issuing forecasts beyond 36 hours. After the law was repealed the new technologies expanded helping forecasters grow.

  30. Video http://www.youtube.com/watch?v=7PiuW2-HP7o

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