Tornado Safety Tips

 

    Tornadoes are one of nature's most powerful and destructive forces. Here's some advice on how to prepare for a tornado and what to do if you're caught in a twister's path.


Safety Tips

• Prepare for tornadoes by gathering emergency supplies including food, water, medications, batteries, flashlights, important documents, road maps, and a full tank of gasoline.
• When a tornado approaches, anyone in its path should take shelter indoors—preferably in a basement or an interior first-floor room or hallway.
• Avoid windows and seek additional protection by getting underneath large, solid pieces of furniture.
• Avoid automobiles and mobile homes, which provide almost no protection from tornadoes.
• Those caught outside should lie flat in a depression or on other low ground and wait for the storm to pass.

Tsunamis

 

    A tsunami is a series of ocean waves that sends surges of water, sometimes reaching heights of over 100 feet (30.5 meters), onto land. These walls of water can cause widespread destruction when they crash ashore.
   These awe-inspiring waves are typically caused by large, undersea earthquakes at tectonic plate boundaries. When the ocean floor at a plate boundary rises or falls suddenly it displaces the water above it and launches the rolling waves that will become a tsunami.
   Most tsunamis, about 80 percent, happen within the Pacific Ocean’s “Ring of Fire,” a geologically active area where tectonic shifts make volcanoes and earthquakes common.
    Tsunamis may also be caused by underwater landslides or volcanic eruptions. They may even be launched, as they frequently were in Earth’s ancient past, by the impact of a large meteorite plunging into an ocean.
    Tsunamis race across the sea at up to 500 miles (805 kilometers) an hour—about as fast as a jet airplane. At that pace they can cross the entire expanse of the Pacific Ocean in less than a day. And their long wavelengths mean they lose very little energy along the way.
    In deep ocean, tsunami waves may appear only a foot or so high. But as they approach shoreline and enter shallower water they slow down and begin to grow in energy and height. The tops of the waves move faster than their bottoms do, which causes them to rise precipitously.
    A tsunami’s trough, the low point beneath the wave’s crest, often reaches shore first. When it does, it produces a vacuum effect that sucks coastal water seaward and exposes harbor and sea floors. This retreating of sea water is an important warning sign of a tsunami, because the wave’s crest and its enormous volume of water typically hit shore five minutes or so later. Recognizing this phenomenon can save lives.
     A tsunami is usually composed of a series of waves, called a wave train, so its destructive force may be compounded as successive waves reach shore. People experiencing a tsunami should remember that the danger may not have passed with the first wave and should await official word that it is safe to return to vulnerable locations.
     Some tsunamis do not appear on shore as massive breaking waves but instead resemble a quickly surging tide that inundates coastal areas.
    The best defense against any tsunami is early warning that allows people to seek higher ground. The Pacific Tsunami Warning System, a coalition of 26 nations headquartered in Hawaii, maintains a web of seismic equipment and water level gauges to identify tsunamis at sea. Similar systems are proposed to protect coastal areas worldwide.

Wildfires

    Uncontrolled blazes fueled by weather, wind, and dry underbrush, wildfires can burn acres of land—and consume everything in their paths—in mere minutes.
   On average, more than 100,000 wildfires, also called wildland fires or forest fires, clear 4 million to 5 million acres (1.6 million to 2 million hectares) of land in the U.S. every year. In recent years, wildfires have burned up to 9 million acres (3.6 million hectares) of land. A wildfire moves at speeds of up to 14 miles an hour (23 kilometers an hour), consuming everything—trees, brush, homes, even humans—in its path.
    There are three conditions that need to be present in order for a wildfire to burn, which firefighters refer to as the fire triangle: fuel, oxygen, and a heat source. Fuel is any flammable material surrounding a fire, including trees, grasses, brush, even homes. The greater an area's fuel load, the more intense the fire. Air supplies the oxygen a fire needs to burn. Heat sources help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires or cigarettes, hot winds, and even the sun can all provide sufficient heat to spark a wildfire.
    Although four out of five wildfires are started by people, nature is usually more than happy to help fan the flames. Dry weather and drought convert green vegetation into bone-dry, flammable fuel; strong winds spread fire quickly over land; and warm temperatures encourage combustion. When these factors come together all that's needed is a spark—in the form of lightning, arson, a downed power line, or a burning campfire or cigarette—to ignite a blaze that could last for weeks and consume tens of thousands of acres.
     These violent infernos occur around the world and in most of the 50 states, but they are most common in the U.S. West, where heat, drought, and frequent thunderstorms create perfect wildfire conditions. Montana, Idaho, Wyoming, Washington, Colorado, Oregon, and California experience some of the worst conflagrations in the U.S. In California wildfires are often made worse by the hot, dry Santa Ana winds, which can carry a spark for miles.
     Firefighters fight wildfires by depriving them of one or more of the fire triangle fundamentals. Traditional methods include water dousing and spraying fire retardants to extinguish existing fires. Clearing vegetation to create firebreaks starves a fire of fuel and can help slow or contain it. Firefighters also fight wildfires by deliberately starting fires in a process called controlled burning. These prescribed fires remove undergrowth, brush, and ground litter from a forest, depriving a wildfire of fuel.
    Although often harmful and destructive to humans, naturally occurring wildfires play an integral role in nature. They return nutrients to the soil by burning dead or decaying matter. They also act as a disinfectant, removing disease-ridden plants and harmful insects from a forest ecosystem. And by burning through thick canopies and brushy undergrowth, wildfires allow sunlight to reach the forest floor, enabling a new generation of seedlings to grow.

Lightnings

 

    Cloud-to-ground lightning bolts are a common phenomenon—about 100 strike Earth’s surface every single second—yet their power is extraordinary. Each bolt can contain up to one billion volts of electricity.

   This enormous electrical discharge is caused by an imbalance between positive and negative charges. During a storm, colliding particles of rain, ice, or snow increase this imbalance and often negatively charge the lower reaches of storm clouds. Objects on the ground, like steeples, trees, and the Earth itself, become positively charged—creating an imbalance that nature seeks to remedy by passing current between the two charges.

    A step-like series of negative charges, called a stepped leader, works its way incrementally downward from the bottom of a storm cloud toward the Earth. Each of these segments is about 150 feet (46 meters) long. When the lowermost step comes within 150 feet (46 meters) of a positively charged object it is met by a climbing surge of positive electricity, called a streamer, which can rise up through a building, a tree, or even a person. The process forms a channel through which electricity is transferred as lightning.

    Some types of lightning, including the most common types, never leave the clouds but travel between differently charged areas within or between clouds. Other rare forms can be sparked by extreme forest fires, volcanic eruptions, and snowstorms. Ball lightning, a small, charged sphere that floats, glows, and bounces along oblivious to the laws of gravity or physics, still puzzles scientists.

    Lightning is extremely hot—a flash can heat the air around it to temperatures five times hotter than the sun’s surface. This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.

    Lightning is not only spectacular, it’s dangerous. About 2,000 people are killed worldwide by lightning each year. Hundreds more survive strikes but suffer from a variety of lasting symptoms, including memory loss, dizziness, weakness, numbness, and other life-altering ailments.

Hurricanes

 

    Hurricanes are giant, spiraling tropical storms that can pack wind speeds of over 160 miles (257 kilometers) an hour and unleash more than 2.4 trillion gallons (9 trillion liters) of rain a day. These same tropical storms are known as cyclones in the northern Indian Ocean and Bay of Bengal, and as typhoons in the western Pacific Ocean.

   The Atlantic Ocean’s hurricane season peaks from mid-August to late October and averages five to six hurricanes per year.

    Hurricanes begin as tropical disturbances in warm ocean waters with surface temperatures of at least 80 degrees Fahrenheit (26.5 degrees Celsius). These low pressure systems are fed by energy from the warm seas. If a storm achieves wind speeds of 38 miles (61 kilometers) an hour, it becomes known as a tropical depression. A tropical depression becomes a tropical storm, and is given a name, when its sustained wind speeds top 39 miles (63 kilometers) an hour. When a storm’s sustained wind speeds reach 74 miles (119 kilometers) an hour it becomes a hurricane and earns a category rating of 1 to 5 on the Saffir-Simpson scale.

    Hurricanes are enormous heat engines that generate energy on a staggering scale. They draw heat from warm, moist ocean air and release it through condensation of water vapor in thunderstorms.

Hurricanes spin around a low-pressure center known as the “eye.” Sinking air makes this 20- to 30-mile-wide (32- to 48-kilometer-wide) area notoriously calm. But the eye is surrounded by a circular “eye wall” that hosts the storm’s strongest winds and rain.

    These storms bring destruction ashore in many different ways. When a hurricane makes landfall it often produces a devastating storm surge that can reach 20 feet (6 meters) high and extend nearly 100 miles (161 kilometers). Ninety percent of all hurricane deaths result from storm surges.

     A hurricane’s high winds are also destructive and may spawn to rnadoes. Torrential rains cause further damage by spawning floods and landslides, which may occur many miles inland.

    The best defense against a hurricane is an accurate forecast that gives people time to get out of its way. The National Hurricane Center issues hurricane watches for storms that may endanger communities, and hurricane warnings for storms that will make landfall within 24 hours.

Floods

 

    There are few places on Earth where people need not be concerned about flooding. Any place where rain falls is vulnerable, although rain is not the only impetus for flood.

   A flood occurs when water overflows or inundates land that's normally dry. This can happen in a multitude of ways. Most common is when rivers or streams overflow their banks. Excessive rain, a ruptured dam or levee, rapid ice melting in the mountains, or even an unfortunately placed beaver dam can overwhelm a river and send it spreading over the adjacent land, called a floodplain. Coastal flooding occurs when a large storm or tsunami causes the sea to surge inland.

    Most floods take hours or even days to develop, giving residents ample time to prepare or evacuate. Others generate quickly and with little warning. These flash floods can be extremely dangerous, instantly turning a babbling brook into a thundering wall of water and sweeping everything in its path downstream.

    Disaster experts classify floods according to their likelihood of occurring in a given time period. A hundred-year flood, for example, is an extremely large, destructive event that would theoretically be expected to happen only once every century. But this is a theoretical number. In reality, this classification means there is a one-percent chance that such a flood could happen in any given year. Over recent decades, possibly due to global climate change, hundred-year floods have been occurring worldwide with frightening regularity.

Earthquakes

   Earthquakes, also called temblors, can be so tremendously destructive, it’s hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors.

     Some 80 percent of all the planet's earthquakes occur along the rim of the Pacific Ocean, called the "Ring of Fire" because of the preponderance of volcanic activity there as well. Most earthquakes occur at fault zones, where tectonic plates—giant rock slabs that make up the Earth's upper layer—collide or slide against each other. These impacts are usually gradual and unnoticeable on the surface; however, immense stress can build up between plates. When this stress is released quickly, it sends massive vibrations, called seismic waves, often hundreds of miles through the rock and up to the surface. Other quakes can occur far from faults zones when plates are stretched or squeezed.

     Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 5 is considered minor or light; 5 to 7 is moderate to strong; 7 to 8 is major; and 8 or more is great.

     On average, a magnitude 8 quake strikes somewhere every year and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis. Smaller temblors that usually occur in the days following a large earthquake can complicate rescue efforts and cause further death and destruction.

   Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.

Avalanches

 

    While avalanches are sudden, the warning signs are almost always numerous before they let loose. Yet in 90 percent of avalanche incidents, the snow slides are triggered by the victim or someone in the victim's party. Avalanches kill more than 150 people worldwide each year. Most are snowmobilers, skiers, and snowboarders.

    Many avalanches are small slides of dry powdery snow that move as a formless mass. These "sluffs" account for a tiny fraction of the death and destruction wrought by their bigger, more organized cousins. Disastrous avalanches occur when massive slabs of snow break loose from a mountainside and shatter like broken glass as they race downhill. These moving masses can reach speeds of 80 miles (130 kilometers) per hour within about five seconds. Victims caught in these events seldom escape. Avalanches are most common during and in the 24 hours right after a storm that dumps 12 inches (30 centimeters) or more of fresh snow. The quick pileup overloads the underlying snowpack, which causes a weak layer beneath the slab to fracture. The layers are an archive of winter weather: Big dumps, drought, rain, a hard freeze, and more snow. How the layers bond often determines how easily one will weaken and cause a slide.

    Storminess, temperature, wind, slope steepness and orientation (the direction it faces), terrain, vegetation, and general snowpack conditions are all factors that influence whether and how a slope avalanches. Different combinations of these factors create low, moderate, considerable, and high avalanche hazards.

    If caught in an avalanche, try to get off the slab. Not easy, in most instances. Skiers and snowboarders can head straight downhill to gather speed then veer left or right out of the slide path. Snowmobilers can punch the throttle to power out of harm's way. No escape? Reach for a tree. No tree? Swim hard. The human body is three times denser than avalanche debris and will sink quickly. As the slide slows, clear air space to breathe. Then punch a hand skyward.

   Once the avalanche stops, it settles like concrete. Bodily movement is nearly impossible. Wait—and hope—for a rescue. Statistics show that 93 percent of avalanche victims survive if dug out within 15 minutes. Then the survival rates drop fast. After 45 minutes, only 20 to 30 percent of victims are alive. After two hours, very few people survive.

Plants soaking up a third of carbon

by: Tom Arup

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    Australia's landscape soaked up a third of national carbon dioxide emissions from burning fossil fuels over the past two decades, a CSIRO assessment has found.

    The three-year study, published in the international journal Biogeosciences, examined the ability of the Australian landscape to absorb greenhouse gases, including how much carbon dioxide is lost and gained through the ''breathing'' of plants and soil under different climate conditions and as carbon dioxide levels rise.

    It found that between 1990 and 2011 Australian plants on average took up 2.2 billion tonnes of carbon dioxide a year.

The higher carbon dioxide levels in the atmosphere increased the growth and development of Australian plants by 15 per cent compared with pre-industrial levels, allowing the Australian landscape to soak up more gas.

    The study's lead author, Dr Vanessa Haverd, said that the ability of plants and soil to breathe in carbon dioxide from the atmosphere was expected to fall in the future as other factors kick in, such as nutrients and water becoming less readily available.

    The study also found that the amount of carbon soaked up by plants is extremely variable year on year, with the results heavily dependent on rainfall and fire conditions.

In wet years, the Australian landscape breathes in more carbon from the atmosphere than all of the total human-induced greenhouse gas emissions.

    But in dry years nearly the same amount is expelled back into the atmosphere.

    Dr. Haverd said the results would help scientists who were working on a global study trying to reconcile ''top up'' and ''bottom up'' estimates of global carbon budgets.

    She said ''top up'' estimates look at measurements of atmospheric concentrations of carbon dioxide. The ''bottom up'' estimates were a series of land and ocean-based assessments being undertaken over larger regions across the globe.

    ''And together they [the bottom-up studies] should be comparable to what we get from the global top-down estimate,'' she said.

     ''It is a different approach to evaluating the global carbon budget, or in other words the exchanges of carbon between the land surface, the ocean and the atmosphere.''

Water waste everywhere but no fines in four years.

by: Nicole Hasham

    SYDNEY WATER has not issued a single fine to residents for hosing down their driveway or using a sprinkler in the middle of the day, allowing water wasters off the hook for the past four years.

    The public have reported more than 2200 alleged breaches to Sydney Water, all of which were investigated. It issued 71 warnings but no fines.

    The findings come as the utility abandons its decade-long push to save water, despite figures showing household usage in Sydney has outstripped most other cities.

Tough water restrictions were lifted in mid-2009 after years of drought and replaced by permanent measures known as Water Wise rules.

     They ban the watering of gardens between 10am and 4pm and stipulate that all hand-held hoses must have a trigger nozzle. Surfaces such as paths and driveways should not be hosed.

Breaches attract fines of $220 for individuals and $550 for businesses. But figures show not a single fine has been handed out since the rules began.

    A spokeswoman for Sydney Water said it could not issue a fine ''on the basis of a neighbour's report''. ''We need to witness the breach or have other solid evidence that will stand up in court,'' she said.

    The chief executive of the Nature Conservation Council of NSW, Pepe Clarke, said it raised questions about Sydney Water's effectiveness as a water watchdog. ''To have such a large number of allegations and investigations but to not issue a penalty for a single one of them suggests that Sydney Water is not taking its role as a regulator seriously,'' he said.

    As Fairfax Media reported on Thursday, Sydney Water has dumped water saving programs for schools, businesses and households. It claims that continuing to drive down use would cost more than the value of the water saved, which would lead to an increase in bills.

    Warragamba Dam is near full capacity and recent water use matches that of four years ago, when the state was in the grip of drought and extensive restrictions and water efficiency programs were in place.

    However, critics said drier conditions would return and abandoning the programs undermined years of efforts to change water use culture. The CSIRO predicts that by 2030 southern Australia may receive up to 10 per cent less rainfall.

The latest National Water Commission performance report shows that average water use by Sydney Water households was second only to Perth in the three years to mid-2011.

    The Sydney Water spokeswoman said restrictions were lifted earlier in Sydney than in Melbourne and Brisbane, where dam levels had reached lower levels, which influenced use. ''Water use is not easily comparable on a year-on-year basis across utilities,'' she said.

    But Mr Clarke questioned why Sydney Water was cutting investment in water saving when consumption remained high compared with other cities.

     The director of the UTS Institute for Sustainable Futures, Stuart White, said Sydney Water had led the way in water saving programs but there was ''more to be done''. He said cuts in efficiency spending had been mirrored by utilities around the country.

     Mr White did not object to a move away from large-scale water recycling, saying smaller, local schemes lowered the cost of carrying water through pipes.

Source: http://www.smh.com.au