Databases
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Britannica Schools This link opens in a new windowBritannica School covers the core subject areas of English, Maths, Science and History. Interactive lessons, activities, games, stories, worksheets, manipulatives, study guides and research tools.
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World Book Encyclopedia This link opens in a new windowOnline version of the complete reference work along with dictionary, atlas, links, magazines, historical documents, audio, video, images, and 3D photograph
Natural Disasters
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Altitude sickness, also known as mountain sickness, occurs when a person who is accustomed to low elevations travels to higher elevations, typically those above 8,000 feet (2,400 meters). Symptoms can range from shortness of breath to a life-threatening accumulation of fluids in the lungs or the brain. Altitude sickness is the body’s reaction to the decreased atmospheric pressure and lower concentration of oxygen that exist at high altitudes. The cause of altitude sickness was first correctly described in 1878, when the French physiologist Paul Bert demonstrated that the symptoms were caused by a lack of oxygen reaching the body’s tissues. Mountain climbers, hikers, skiers, and people who live at high elevations are most likely to suffer from altitude sickness.
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When you’re flying, mountain climbing, hiking, or driving at a high altitude, your body may not get enough oxygen. The lack of oxygen can cause altitude sickness, which often shows up as headaches and insomnia. Altitude sickness generally occurs at altitudes of 8,000 feet and above. People who aren’t accustomed to these high altitudes are most vulnerable.
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Altitude sickness occurs when you cannot get enough oxygen from the air at high altitudes. This causes symptoms such as a headache, loss of appetite, and trouble sleeping. It happens most often when people who are not used to high altitudes go quickly from lower altitudes to 8000 ft (2438 m) or higher. For example, you may get a headache when you drive over a high mountain pass, hike to a high altitude, or arrive at a mountain resort.
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Altitude sickness or mountain sickness is caused by ascending too rapidly, which does not allow the body enough time to adjust to reduced oxygen and changes in air pressure. Symptoms include headaches and vomiting. Altitude sickness can be harmful or fatal.
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A large mass of snow moving rapidly down a mountain slope is known as an avalanche. The snow breaks loose from its surroundings and quickly collects more snow as it plunges downslope. Avalanches can also be formed of rock, earth, or soil, but such events are usually called landslides.
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Surviving avalanches can depend on luck; therefore, it is always better to avoid them in the first place. Remember that only 1 of 3 victims buried without a beacon survives. If you are caught, first try to escape to the side, or grab a tree or rock. If you are knocked down, get rid of your poles, skis and or snowshoes, and a heavy pack. Swim with the avalanche to try to stay on top and avoid trees. When the avalanche slows down, reach the surface or make an airpocket.
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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.
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Fires must be fought every day in most countries. Millions of fires start each year and cause great destruction of property and much human suffering. In the United States alone, in 1981, 6,800 people died in some of the almost 3 million fires that occurred and the cost of damaged or destroyed property was estimated at nearly 7 billion dollars.
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More and more people are making their homes in woodland settings, rural areas or remote mountain sites. While residents in these areas enjoy the beauty of the environment around them, they also face the very real danger of wildfires.
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Are you bushfire prepared?
Are your family and home at risk?
You don’t have to live in the bush to be threatened by bushfire, just close enough to be affected by burning material, embers and smoke. -
Out of the many natural disasters we have, wild fires would be one that is very common, very difficult to fight, and maybe the most dangerous.
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Bushfires and grassfires are common throughout Australia. Grassfires are fast moving, passing in five to ten seconds and smouldering for minutes. They have a low to medium intensity and primarily damage crops, livestock and farming infrastructure, such as fences. Bushfires are generally slower moving, but have a higher heat output. This means they pass in two to five minutes, but they can smoulder for days. Fire in the crown of the tree canopy can move rapidly.
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ach year thousands of fires destroy or damage houses, sheds and garages, commercial and industrial buildings, vehicles and vast hectares of bushland throughout Western Australia (WA).
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A mass of rock or soil moving down a slope is known as a landslide. A similar event involving snow is called an avalanche. Landslides differ in their type, speed, extent, and destructiveness. In some types, such as a rockfall, the material separates from the slope and falls rapidly. In a mudflow or debris flow, loose soil, rock fragments (known as debris), or volcanic ash becomes saturated with water and suddenly pours downslope like a fluid, often very fast. Such flows can rush down a mountainside at speeds as great as 200 miles (320 kilometers) per hour, but most flow at about 30–50 miles (50–80 kilometers) per hour. In some other kinds of landslides, the material shifts down at a moderate or slow speed, sometimes even creeping imperceptibly for years.
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Landslides have occurred in almost every state and can cause significant damage. The term landslide describes downhill earth movements that can move slowly and cause damage gradually, or move rapidly, destroying property and taking lives suddenly and unexpectedly. Most landslides are caused by natural forces or events, such as heavy rain and snowmelt, shaking due to earthquakes, volcanic eruptions and gravity. Landslides are typically associated with periods of heavy rainfall or rapid snowmelt and tend to worsen the effects of flooding. Areas burned by forest and brush fires are also particularly susceptible to landslides.
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A landslide is the movement of rock, debris or earth down a slope. They result from the failure of the materials which make up the hill slope and are driven by the force of gravity. Landslides are known also as landslips, slumps or slope failure.
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A volcano is a vent, or opening, in Earth’s surface through which molten rock, gases, and ash erupt. The word also refers to the form or structure, usually conical, produced by accumulations of erupted material. In some volcanic eruptions, the molten rock—called magma when it is underground and lava when it reaches the surface—flows slowly out of the vent. In more violent eruptions, lava shoots straight up, and rock fragments are ejected in a great cloud of ash-laden gas that rises high into the air.
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Volcanoes are awesome manifestations of the fiery power contained deep within the Earth. These formations are essentially vents on the Earth's surface where molten rock, debris, and gases from the planet's interior are emitted.
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Explosive volcanoes blast hot solid and molten rock fragments and gases into the air. As a result, ashflows can occur on all sides of a volcano and ash can fall hundreds of miles downwind. Dangerous mudflows and floods can occur in valleys leading away from volcanoes. If you live near a known volcano, active or dormant, be prepared to follow volcano safety instructions from your local emergency officials.
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Volcanoes form when magma reaches the Earth's surface, causing eruptions of lava and ash. They occur at destructive (compressional) and constructive (tensional) plate boundaries.
The immediate effects of volcanic eruptions can be devastating, but they may be beneficial in the long term. -
A volcano is a vent or chimney which transfers molten rock known as magma from depth to the Earth's surface. Magma erupting from a volcano is called lava and is the material which builds up the cone surrounding the vent.
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The earth's mountains, plains, plateaus, soils, rocks, etc. as we see it today is believed to have gone through many phases, with about 80% of it being carved out by the action of volcanoes.