Severe+Rain-Green

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Korinna G and Mara R.  Green Class

media type="custom" key="12156420" width="80" height="80" The heavy and continuous descent of water from the atmosphere can be referred to as severe rain. Rain is precipitation that reaches the ground in liquid form after water vapor condenses in the atmosphere. The size of the drop, length of a rain shower, and intensity of rain fall, depend on the cloud from which the rain falls. People mostly view rain as an innocent natural process; however, sometimes rain is so severe that it can bring harm to people, animals, and the environment in which they live. Disasters such as hurricanes, thunderstorms, flashfloods and microbursts can all be associated with torrential downpour. The most severe storms have resulted in human deaths and costly property damage related to the severe rainfall. Although a little drizzle may be irksome, it is important to remember that rain can escalate and become severe, having a lasting impact on the earth that, in some cases, may be catastrophic. You may be wondering: what determines if rain is severe or "heavy,"? Rainfall greater than or equal to 50 mm in 24 hours can be considered severe (6). If you are interested to see if the rainfall in your area counts as severe, check out this link to find a constantly updated map of daily heavy precipitation: []

A specific result of severe rain is flash flooding. Flash floods are caused by excessive rainfall in a short period of time: usually less than 6 hours (3,8). They are capable of destroying landscape, river beds and modern streets, and can occur during or after the original rain sequence (8). Additionally, thunderstorms will often pair with severe rain. Thunder, lightning and flash flooding are severe weather events and can be associated with severe rain.

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Severe rain is the cause of the devastation left behind by most natural disasters. The flooding and sudden flash flooding that result from severe rain are said to be the most deadly natural disasters in the world (3,6). In the United States, flash flooding is the #1 weather-related killer (6). The severity of the rain uproots trees, damages homes, and makes transportation impossible (1,6,8). Consequently, during and after severe rain storms thousands of people are left homeless, and sometimes starving, because the food, transportation, and residential resources they once had, have been made inaccessible. Additionally, flash floods are sudden, and usually unexpected (5). After long periods of intense rainfall, there is so much water in the ground that it can no longer be absorbed. As a result, water runs down into valleys, flooding rivers, bursting dams, and sometimes causing mudslides; catastrophes that can wipe out whole towns (5). Additionally, severe rain is often associated with other storms such as hurricanes and thunderstorms, which bring dangers of their own. Many may question, just how much can a severe rainstorm really affect YOU? Well, water weighs approximately 62.4 pounds per cubic foot. In addition, it flows down stream at a rate varying from 6-12 miles per hour (5). With this dangerous weight and shocking speed, it is clear that rainstorms can escalate to a point at which they pose a severe hazard to humans. A person could be knocked right off their feet if caught in a sudden surge of water. Today the Northeast alone has seen a 67 percent increase in the amount of rain or snow falling in the heaviest storms (7). With severe rains becoming even more prevalent, the dangers itemized above must be looked out for; things such as mudslides, flooding of rivers and bursting of dams will become more common and also more severe.

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See some of the damage caused by flash flooding for yourself in this video!

media type="custom" key="12130240" Severe rain, along with most other severe precipitation, forms in Cumulonimbus clouds. It takes very hot and humid air to create enough instability for these clouds to form (2). In addition convergence, orographic lifting, or frontal wedging, help force air to rise. When this happens, the air molecules are forced higher up into the atmosphere where there is a low pressure zone. As a result of all these rising molecules, a strong updraft, or upward moving current of air, is created (1). Because they have by passed the force of the densely packed molecules below, these lifted molecules can spread apart and, due to adiabatic temperature change, will cool as a result of this expansion. As these molecules cool, their capacity, or amount of water vapor they are able to hold decreases, causing the relative humidity, or percent water vapor in the air to increase. Once the relative humidity reaches 100%, the dewpoint, condensation will start to form. This happens because the air is completely saturated and cannot hold anymore water vapor, and therefore, has to release water into the air. This condensation takes the form of tiny droplets that remain suspended in the atmosphere, as they don't have enough mass to be pulled down to earth by gravity. If the atmosphere stays under these conditions for an extended period of time, more and more condensation will form and the droplets will become closer and closer together and eventually combine to become massive enough that they fall down to earth. When the water falls, along with it comes a current of air, a downdraft. As the water droplets fall, they collide and coalesce with other slower moving droplets along the way. This process, which builds large heavy raindrops is called the collision-coalescence process (2). As long as there is both an updraft (to keep the cloud growing) and a downdraft (forcing heavy rain to fall downwards, and allowing for the collision-coalescence process) you have a mature rainstorm that will last until the updraft dies down, essentially "killing" the cloud (2).

media type="custom" key="12130248" One of the most catastrophic effects of severe media type="youtube" key="1CPj0QZCubk" height="283" width="378" align="right"rain occurred on February 3, 2009 in Bombay India where the highest amount of rainfall ever recorded fell (about 94 centimeters, or 37 inches) and killed at least 513 people. (7) The heavy rain took its toll on the country with the 2nd largest population in the world (about 1.2 billion) (4), it created mudslides, flooded cars within minutes, and separated many people from hospitals and sources of food and water. The rains occurred so quickly that many people were stuck in their cars and drowned. Pallavi Jain was one of the lucky survivors to pry open her door before the rain hit too hard (7), but others were not so lucky. For each foot of rising water applies 500 lbs of lateral force to a car, and the uncontrollable water entrapped people causing many of the 500+ deaths India suffered (7). Overall though, it was drowning, being crushed by falling walls, and electrocution that were the major cause of the deaths from this flood (7). Additionally, severe rains such as this monsoon, seen in India, elevated a factor of panic amongst many of the residents. At least fifteen people, including seven children were killed in a stampede when a rumor spread that a dam had broken (7). Clearly, severe rain is not something to joke about, and it is a natural disaster with the capability to kill many. The massive destruction that it caused in India is just one of many events that demonstrate its deadly potential and also stand as a warning to all, so that we should become more aware of our environment.

 This video demonstrates the devastating effect of severe rain on Indiaalkdsfja;ldsfkja;lsdfja;lsdjf;alsdfjka;sldkjfasl;dkf adsfadsfasdfdsafasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfsl This video demonstrates the devastating affect of severe rain on India

media type="custom" key="12130250" Severe rain can cause flash flooding in any given time. Whether it be a short time in which heavy downpour occurs, or a result of hours of excessive rainfall, it is important that people be aware of their surroundings and be ready in the case of an emergency (5). The most instinctive and most important thing to remember is that no matter what, in the case of severe rain always head for higher ground to avoid the torrents of water (5). In addition, there are some pre-flood steps that can be taken so that in the event of a flash flood, or any other smaller flood, you can be primed. For instance, it is not a bad idea to take careful note of your area so that you will have a place to go in an emergency, keep your cars and motor vehicles well equipped with gas in case of a gas station breakdown, and have a disaster kit at the ready so that it can be grabbed on the go. In an everyday disaster kit there should be at the least, a portable radio, flashlight, extra batteries, a first aid kit and manual, personal identification, money and credit cards, map of the area along with phone numbers of potential places to go, waterproof matches, rubber boots, rubber gloves and a signal flare (5,9). This can be prepared in advance so you are ready for anything that comes your way. As discussed earlier, being in a motor vehicle during a storm can be very dangerous because of the force of water exerted on car doors. If you should find yourself in any sort of motor vehicle during a severe rainstorm, be sure to stay off of flooded roads and evacuate the car if necessary. DO NOT take risks; at the slightest chance of danger it is always better to leave the car for higher ground (5). Likewise, during a flood in general it is always a good idea to take extra precautions. At the first warning of a flash flood, you should immediately abandon low grounds and avoid power lines, so as not to be electrocuted, which is a common occurance shown in the historical example above where 273 people in Bombay died mostly from either drowning, the falling of walls, or electrocution (5,7,9). After a flood many people let down their guard, but it is important not to be too eager to return to daily life. Upon return, be sure to dispose of fresh food that may have come in contact with the flood waters and be sure to be careful with electronics as many may cause harm to you or others if wet. There are many steps that can be taken to insure safety in the event of this treacherous natural disaster that will make a difference if you are to ever come in contact with severe rain.

Look at this [|website] for an interactive simulator of different flash flood scenarios!

media type="custom" key="12130256" List all the sources used in proper format 1) "Severe Thunderstorms." //Bureau of Meteorology//. Common Wealth of Australia, n.d. Web. 12 Jan. 2012. [].

2) Tarbuck, Edward J., Frederick K. Lutgens, and Dennis Tasa. "Chapter 18 Moisture, Clouds, and Precipitation." //Prentice Hall Earth Science//. Needham, Mass. ; Upper Saddle River, N.J.: Pearson/Prentice Hall, 2006. 520-22. Print.

3) Moorthy, V. Krishna, and Bhaskar Karnick. "Floods and Flash Floods." //Vigyan// //Prasar//. N.p., n.d. Web. 12 Jan. 2012. [].

4) "CIA - The World Factbook." //Welcome to the CIA Web Site — Central Intelligence Agency//. Central Intelligence Agency. Web. 12 Jan. 2012. [].

5) "Flash Flooding." //St. Charles County Missouri Department of Community Health & the Environment//. St. Charles County Department of Community Health & The Environment. Web. 12 Jan. 2012. .

6) "SWIC - Heavy Rain / Snow." //Severe Weather Information Centre//. World Meteorological Organization. Web. 12 Jan. 2012. [].

7) India: Monsoon Death Toll Tops 500 - CBS News." //Breaking News Headlines: Business, Entertainment & World News - CBS News//. CBS News, 11 Feb. 2009. Web. 12 Jan. 2012. [].

8) "Flood and Flash Flood Definitions." //National Weather Service Southern Region Homepage//. National Weather Service. Web. 12 Jan. 2012. [].

9) "Disaster Supplies Kit." //The Disaster Center - Home Page//. National Disaster Education Coalition, 1999. Web. 12 Jan. 2012. .

10) "566 An Analysis of Heavy Rainfall Weather Systems over Louisiana (2010 - 90annual_24hydro)." //AMS Supported Meetings//. University of Louisiana, 20 Jan. 2010. Web. 17 Jan. 2012. .

11) Gillis, Justin. "Heavy Rains Linked to Humans." //Nytimes.com//. New York Times, 16 Feb. 2011. Web. 12 Jan. 2012. <http://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1>.