2 hrly gs ch 06 natural disasters

Natural Disasters

What is a Natural Disaster?Definition:The effect of a natural hazard, which leads to financial, environmental or human losses

Natural events that kill people or damage property or the environment

List of Natural DisastersFollowing are the different weather phenomena we are going to discuss:

Avalanche BlizzardEarthquakeHailstormHurricanesLightningTornadoTsunamiTyphoonVolcanoWildfire

Avalanche

What is an Avalanche?Definition: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.

What causes Avalanche?A vibration or movement like the voice of a person or a train Certain weather conditions like wind and rainA rock or a piece of ice can shake the snow to slide down the mountain

Avalanches kill more than 150 people worldwide each year

Victims caught in these events seldom escape

Once the avalanche stops, it settles like concrete. Bodily movement is nearly impossible

Blizzard

What is a Blizzard?Definition:A severe snowstorm that usually has very cold temperatures and high winds. These two conditions create blowing snow

A long-lasting snowstorm with very strong winds and intense snowfall

Blizzard Warning:Heavy snow and strong winds will produce a blinding snow, near zero visibility, deep drifts and life-threatening wind chill

The blowing winds and low temperature can cause frostbite and/or hypothermia

Earthquake

What is an Earthquake?Definition:An earthquake is what happens when two blocks of the earth suddenly slip past one another

Fault plane The surface where the slip occursHypocenter The location below the earths surface where the earthquake startsEpicenter The location directly above it on the surface of the earth

The Plate Tectonic Theory The earth's crust and upper mantle is composed of several large, thin, relatively rigid plates that move relative to one anotherThe plates are all moving in different directions and at different speeds. Sometimes the plates crash together or pull apart. When this happens, it commonly results in earthquakes

Earthquakes can be felt over large areas although they usually last less than one minute

How are earthquakes recorded?By instruments called seismographsThe recording they make is called a seismogram

When an earthquake causes the ground to shake, the base of the seismograph shakes too, but the hanging weight does not

Instead the spring or string that it is hanging from absorbs all the movement

The difference in position between the shaking part of the seismograph and the motionless part is what is recorded

Volcano

What is a Volcano?Definition:An opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface

Volcanoes are generally found where tectonic plates are diverging or convergingthere is stretching and thinning of the Earth's crust in the interiors of plates

Volcanoes are found in three states An extinct volcano will never erupt againA dormant volcano has not erupted in 2000 yearsAn active volcano has erupted recently and is likely to erupt again

Advantages of VolcanoMany people rely on volcanoes for their everyday survival. Geothermal energy can be harnessed by using the steam from underground which has been heated by the Earth's magma. Used to drive turbines in geothermal power stations to produce electricity for domestic and industrial use. Used in Iceland and New Zealand

Tourist attraction: Millions of visitors every year visit the volcano, hot springs and geysers.Tourism creates many jobs for people like in hotels, restaurants, gift shops and locals can act as tour guidesLava contains minerals which can be mined once it has cooled. These include gold, silver, diamonds, copper and zinc

Volcanic areas often contain some of the most mineral rich soils in the world. This is ideal for farming. These areas can be cultivated to produce healthy crops and rich harvests

Tsunami

What is a Tsunami?Definition:A series of large ocean wave usually caused by an underwater earthquake or a volcanic explosionThe waves may travel in the open sea as fast as 450 miles per hour

Tsunamis can reach the heights of over 100 feet (30.5 meters)

They are NOT tidal waves

Tidal waves are caused by the forces of the moon, and planets upon the tides, as well as the wind as it moves over the water.

Whereas a tsunami flows straight. This is why they cause so much damage

Tornado

What is a Tornado?Definition:A violent rotating column of air extending from a thunderstorm to the groundVertical funnels of rapidly spinning air

Also known as TwisterWind speed: up to 300 mphFunnels width: up to 660 feet (200 meters)

Tornadoes are formed when moist warm air and cool dry air collide to create unstable atmosphere

This collision creates a shift in the wind direction and speed

However, tornadoes are still a mystery. Scientists still are not very sure what causes and finishes them

Tornadoes can occur anywhere and any time as long as the proper conditions are thereBut the United States is a major hotspot with about a thousand tornadoes every year. "Tornado Alley," a region that includes eastern South Dakota, Nebraska, Kansas, Oklahoma, northern Texas, and eastern Colorado, is home to the most powerful and destructive of these storms.

Tropical Cyclones

What is a Tropical Cyclone?Definition:A storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain

It is formed over oceans

Tropical cyclones gather heat and energy through contact with warm ocean watersThey form only over warm ocean waters near the equator

The warm, moist air over the ocean surface rises upward

Because this air moves up and away from the surface, there is less air left near the surface

In other words, the warm air rises, causing an area of lower air pressure below

Tropical cyclone a generic termDepending on its location, is referred to by names:HurricaneTyphoonCyclone

What is a Hurricane?Definition:Only tropical cyclones that form over the Atlantic Ocean or eastern Pacific Ocean are called hurricanes

What is a Typhoon?Definition:Only tropical cyclones that form over the western Pacific Ocean are called typhoons

What is a Cyclone?Definition:Only tropical cyclones that form over the Indian Ocean areas are called cyclones

Wildfire

What is a Wildfire?Definition:Any uncontrolled fire often occurring in wildland areas

Also known as a wildland fire, forest fire, vegetation fire, grass fire, or bush fire

Speed: up to 23 kilometers an hour

Consume everythingtrees, brush, homes, even humansin its path

Three conditions are needed for a wildfire to burn, which firefighters refer to as the fire triangle: Fuel any flammable material surrounding a fire like trees, grass, houses etcOxygen air supplies itHeat source help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires or cigarettes, hot winds, and the sun

Wildfires can occur anywhere, but are common in the forested, vegetated, and grasslands areas

Fires are particularly prevalent in the summer and fall, and during droughts when fallen branches, leaves, and other material can dry out and become highly flammable

How do firefighters put out the wildfires?Use a tool known as a pulaski, a combination of an ax and hoe used to dig a fireline. A fireline is a strip of land from which all brush and debris have been cleared to rob a wildfire of its fuel.

Use hotshots and smoke jumpers to clear a large path in a big circle around the fire so the blaze is contained in a ring of dirt. When the fire reaches this area, it runs out of fuel and starves to death.

If the fire is too large, however, planes and helicopters fly overhead, dropping water and special chemicals that smother the flames. This pink, fire-retardant chemical is called sky jell-o

Hail Storm

What is a Hailstorm?Definition: HailA form of solid precipitation in the form of irregular lumps of clear ice and compact snow

Any thunderstorm which produces hail that reaches the ground is known as a hailstorm

Spherical in shape with a diameter up to 0.5 inchIn rare cases, hailstones having diameters up to 6 inches have been observedConditions necessary for Hail formation:Strong thunderstorms cloudsStrong motion of air Large water dropletsA good portion of the cloud layer is below freezing 0 C

Hail causes much damage to:Farmers cropsWheat, corn, soybeans, and tobacco are the most sensitive crops to hail damageLivestock HumansMassive hails can cause concussions or fatal head traumaMan-made structuresEspecially glass structuresAirplanes and automobiles

Methods of detecting hail-producing thunderstorms Weather satellitesWeather radar imagery

Severe weather warnings are issued for hail when the stones reach a damaging size

Lightning

What is a Lightning?Definition:A bright flash of electricity produced by a thunderstorm

All thunderstorms produce lightning and are very dangerous

Lightning kills and inju