by Bill Evans
Hail causes a tremendous amount of crop damage worldwide. It can shred crops in a matter of minutes. In the United States alone, the cost runs into hundreds of millions of dollars a year. Farmers offset this by buying crop insurance. Illinois farmers buy more crop insurance than anyone else, spending $600 million each year. However, hail is most common in an area called hail alley, where Colorado, Wyoming, and Nebraska meet.
Hail is being battled around the world by a technique called cloud seeding. Insurance companies, as well as cities and countries around the world, have been using cloud seeding to save crops and property. The practice is very common in China, where feeding the country’s large population has forced the nation’s leaders to turn to cloud seeding to lessen crop damage caused by hail.
You’re Using Seeds to Grow Clouds? What Are You Trying to Make, a Chia Cloud?
What is cloud seeding? I have seen it done and I can tell you it’s very cool. An airplane flies into storm clouds during a severe thunderstorm. This is very dangerous as the plane has to fly right into the lower layers of the thunderstorm to perform its work. The tremendous downdrafts of the storm, also known as wind shear, could push the aircraft right into the ground, so the pilot has to be very careful!
Attached to the aircraft’s wings are flares. They look something like roadway flares or Roman candles. Inside the flares is a chemical called silver iodide.
Flying in the teeth of the storm, the plane drops millions of silver iodide smoke particles. The particles act as artificial ice crystals and freeze the water drops in the storm’s updraft. In hail storms, the rapid formation of cloud water occurs in the lower part of the cloud. When this exceeds the rate of natural ice crystal growth, it creates an environment ripe for hail. The billions of ice crystals formed from seeding freeze the supercooled water, which results in the storm producing smaller, less dangerous hailstones.
The thousands of ice crystals made from the silver iodide smoke particles will start to crystallize using up the liquid water so that water isn’t available for hail to grow to large size. The more water used to make ice crystals means less water left to form larger hailstones.
St. Louis, Missouri, is the number one site of hail damage in the United States with a record $1.9 billion. Calgary, Alberta, Canada, began an aggressive cloud-seeding program after a 30-minute hailstorm in 1991 caused a record 116,000 insurance claims to be filed, resulting in a payout of what today would be $1 billion. With populations growing and property values skyrocketing, cloud seeding has become a very cost-effective way to battle hail!
I’m Going Down, Down, Down, in a Burning Ring of Fire!—or, Shake It, Shake It, Baby!
Did you know that 80 percent of the planet’s earthquakes occur along the rim of the Pacific Ocean, in an area called the Ring of Fire? This zone runs along the west coast of South, Central, and North America, from the tip of the southern continent through the Aleutian Islands, and then continues to circle the Pacific Ocean along the eastern coast of Asia, south to Japan and the Philippines, then farther south around the eastern side of Australia to New Zealand, for a total distance of roughly 50,000 miles. The Ring of Fire is home to 452 volcanoes—that’s 75 percent of the world’s active and dormant volcanoes.
I’m sure you’re familiar with the basics of an earthquake, the tremendous shaking of the ground that is caused by an abrupt shift of rock along a fracture in the Earth, called a fault. Earthquakes usually last no longer than 30 to 40 seconds. But in those few seconds, an earthquake releases stress that may have been accumulating within the rock for hundreds of years.
Earthquake damage in Turkey
FEMA/Dane Golden
Scientists believe that most earthquakes are caused by slow movements inside the Earth that push against the Earth’s brittle, relatively thin outer layer, causing rocks to break suddenly. These are not rocks you can put in your hand, but gigantic rocks that take up many hundreds of square miles!
The surface of the Earth is covered with immense, large, rigid plates of rock, which move slowly and continually in response to the flow of molten rock within the Earth. The study of this motion is called plate tectonics. In some places, the plates rub against each other; in others, one plate sinks beneath another; and still in others, the plates shift away from each other.
When any of these things happen, the usual smooth movement of the plates is disrupted. Sometimes, plates become jammed together at their edges while the rest of the plate continues to move. The rocks along the edges of the plates become distorted with what in earthquake lingo is called a strain as the plates flex. Over time, the strain builds up to the point where the rock cannot bend anymore. With a lurch, the rock breaks and the two plates move. An earthquake is the shaking that radiates out from the breaking rock.
The San Andreas Fault in California marks one place where the giant rock plates rub against each other. In 1906, the release of strain caused the Great San Francisco Earthquake. The quake, the aftershocks, and the fires triggered by the tremors, which burned for three days, killed somewhere between 700 and 3,000 people. That is the largest death toll ever for an earthquake in the United States.
Earthquake damage in California
U.S. Geological Survey/Department of the Interior
A view of San Francisco after the 1906 earthquake.
U.S. Geological Survey/Department of the Interior
U.S. Geological Survey/Department of the Interior
The size of an earthquake is indicated by a number called its magnitude. Magnitude is calculated from a measurement of either the strength or the length of time of recorded seismic waves, or what I like to call the “shake, rattle, and roll.” Magnitude is determined from measurements made from seismograms and not on reports of the shaking or interpretations of building damage. (This is different from the Fujita scale described in the chapter about tornadoes, which is based solely on the damage to buildings and other structures.)
Who Moved My Plate?
The rates of plate movement range from about three-quarters of an inch to 4.5 inches per year. That movement can be measured by precise ground-surveying techniques using laser-electronic instruments. Global Positioning System (GPS) has been very useful for studying the shifts in the Earth’s crust. Twenty-one satellites are currently in orbit 13,777 miles above the Earth as part of the NAVSTAR system of the U.S. Department of Defense. These satellites continuously transmit radio signals back to Earth. To determine its precise position on Earth (longitude, latitude, elevation), each GPS ground site must simultaneously receive signals from at least four satellites, recording the exact location of each satellite and the time when its signal was received. By repeatedly measuring distances between specific points, geologists can determine if there has been active movement along faults or between plates. The separations between GPS sites are already being measured regularly around the Pacific basin.
“Yo, Plates, We’ll Be Watching YOU!”
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Deadliest Earthquakes of All Time!
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Dude, Take It from “Tommy Tsunami,” You Do Not Want to Catch That Wave!
It’s very exciting to sit at the beach on a sunny blue-sky day and watch giant waves come crashing ashore. I love watching surfers try to keep those great monster waves from swallowing them. Laird Hamilton is my favorite surfer. He’s extremely cool when it comes to riding gigantic waves that are five to eight stories high, shooting the curl on his board at up to 80 mph. However, the waves Laird and his surfer pals ride look nothing like the real killer of a wave called a tsunami. Most people who have not experienced a tsunami imagine that it looks like one of those towering, surfable waves with a giant curl. But that’s not what a tsunami looks like.
A tsunami is a series of huge waves that occur as the result of a violent underwater disturbance such as an earthquake or a volcanic eruption. The waves travel in all directions from the epicenter of the disturbance, much like the ripples that happen when a rock is thrown into a pond. The waves may tr
avel in the open sea as fast as 450 mph. In the open ocean, tsunami waves are not generally large—hence the difficulty in detecting the approach of a tsunami. In the open ocean, they would not even be felt by ships because their wavelength is hundreds of miles long with a height of only a few feet. But as these powerful waves approach shallow waters along the coast, their velocity is slowed and the waves swell to a great height before smashing into the shore. Wave heights have been known to reach more than 100 feet (30.5 meters)! Even a wave that is 10 to 20 feet high can cause many deaths or injuries.
National Oceanic and Atmospheric Administration/Department of Commerce
The first wave is usually not the largest or most significant wave in the series. Furthermore, one coastal community may experience no damaging waves while another, not that far away, may be pounded by deadly, destructive waves. Depending on a number of factors, some low-lying areas could experience severe inland flooding of water and debris of more than 1,000 feet.
So Who Is “Sue Nomee”?
Tsunami is the Japanese word for “harbor wave.” Tsunamis used to be mistakenly referred to as tidal waves, but they have nothing to do with the tides.
The deadliest tsunami in history happened on December 26, 2004, when a 9.0 magnitude earthquake ruptured the floor of the Indian Ocean off the northwest coast of the Indonesian island of Sumatra. The earthquake triggered the deadliest tsunami in world history. More than 225,000 people died from the disaster; thousands were injured, thousands remain missing, and millions were left homeless.
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Wave It Good-bye!—Deadliest Tsunamis in History
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How Will I Know If a Tsunami Is Coming?
The National Oceanic and Atmospheric Administration (NOAA) uses many tools to detect an oncoming tsunami. Tsunami warning centers use earthquake information, tide gauges, and a new tool from NOAA—tsunami detection buoys, developed by NOAA’s Pacific Marine Environmental Laboratory. Six of these buoys are now deployed in the North Pacific to help scientists determine whether a tsunami has been generated and is heading for North American coastlines. More buoys are needed, however, especially since the buoys can suffer outages in the harsh North Pacific Ocean.
National Oceanic and Atmospheric Administration/Department of Commerce
Tsunami Watches and Warnings
Tsunami Warning
A high-level threat. Indicates that a tsunami is imminent and that coastal locations in the warned area should prepare for flooding. The initial warning is typically based on seismic information alone. Earthquakes over magnitude 7.0 trigger a warning covering all coastal regions within 2 hours tsunami travel time from the epicenter. When the magnitude is over 7.5, the warned area is increased to 3 hours tsunami travel time. As water level data showing the tsunami is recorded, the warning will be cancelled, restricted, or expanded as conditions indicate.
Tsunami Watch
A lower-level threat than a tsunami warning. The area included in the watch is based on the magnitude of the earthquake and the borders of the warning zone. For earthquakes over magnitude 7.0, the watch area is 1 hour tsunami travel time outside the warning zone. For earthquakes over magnitude 7.5, the watch area is 3 hours tsunami travel time outside the warning zone. Subsequent bulletins will either upgrade the watch to a warning or cancel it, depending on the severity of the tsunami.
Upon receipt of tsunami watches and warnings, coastal National Weather Service (NWS) offices activate the Emergency Alert System (EAS) via NOAA Weather Radio. All broadcasters (TV, AM/FM radio, and cable TV) receive the tsunami EAS message, as well as anyone who has a weather radio receiver (this includes healthcare facilities, schools, businesses, and homes). NOAA Weather Radio also activates the All-Hazard Alert Broadcast (AHAB) units located in remote coastal areas, alerting people in isolated locations.
Where Do the Watches and Warnings Come From?
Two tsunami warning centers look for earthquakes and any indications that a tsunami might have been generated. If they pick up evidence of a tsunami, they issue watches and warnings for their assigned areas.
The West Coast/Alaska Tsunami Warning Center in Palmer, Alaska, covers California, Oregon, Washingon, Alaska, and British Columbia.
The Pacific Tsunami Warning Center in Ewa Beach, Hawaii, covers the Aloha State as well as all other American territories in the Pacific. It also serves as the International Tsunami Warning Center for twenty-five other member countries in the Pacific Ocean Basin.
If you live on the coast, make an evacuation plan, keep it updated, and be ready to use it. There’s nothing you can do to stop a tsunami, but you can be ready with the right response when “Tommy Tsunami” pays you a visit!
I Dunno Where I’m Gonna Go When the Volcano Blows!
When I think of a volcano, the first image that comes to mind is a large, tall mountain with orange fire and lava spewing out of the top. Ka-boom! Volcanoes can explode violently, destroying everything within a few miles of the eruption in a matter of minutes. But there are many volcanoes where the lava seeps out so slowly that you can actually safely walk around them! The severity of a volcano’s eruption depends on the thickness and composition of its magma.
Mount St. Helens volcano, Washington
U.S. Geological Survey/Department of the Interior
A volcano is an opening, vent, or rupture in the surface of the planet that allows material from inside the Earth to escape. When watching an erupting volcano, many of us may feel the same emotions as people in ancient times who believed volcanoes were supernatural beings. We stand in awe of this force of nature and are unnerved that what was once a peaceful mountain with pretty snow on top, has been transformed into a raging beast throwing a horrendous, molten magma, fire-spewing fit!
U.S. Geological Survey/Department of the Interior
That was the case when Mount St. Helens in the state of Washington erupted in 1980; it had not erupted for 123 years. Most people thought Mount St. Helens was a beautiful, peaceful mountain, not a dangerous volcano.
Volcanoes are generally found where tectonic plates meet violently—where they are pulled apart or jammed together. Volcanoes are rarely found where two tectonic plates slide past each other.
Worldwide, there are 1,500 active—that’s right, active— volcanoes. Six hundred of those are on the land and the rest are on the ocean floor. All the volcanoes of the world, active, dormant, or extinct, are important because volcanoes make up 80 percent of the Earth’s surface.
Hot Magma, Baby!
When magma seeps or blasts onto the Earth’s surface, it’s called lava. How explosive an eruption is depends on how runny or sticky the magma is. If magma is thin and runny, gases easily escape from it. When this type of magma erupts, it flows out of the volcano. Magma that’s thick and sticky doesn’t flow easily and blocks the gases from escaping. Pressure builds up until the gases escape violently and explode. In this type of eruption, the magma blasts into the air and breaks apart into pieces called tephra. Tephra can range in size from tiny particles of ash to house-size boulders!
Explosive volcanic eruptions can be dangerous and deadly. Clouds of hot tephra can blast out from the side or top of a volcano. When Mount St. Helens erupted, the top blew clean off the mountain and fiery clouds raced down the mountainside, destroying everything in their path.
Volcanic ash falls back to Earth as if it were powdery snow, but of course it doesn’t melt. If the ashfall is thick enough, it can suffocate plants, animals, and humans. When hot volcanic materials mix with water from streams or melted snow and ice, mudflows are formed. Mudflows can be as dangerous as lava flows. They have buried entire communities near erupting volcanoes.
Where Do These Bad Boys Come From?
Like earthquakes, volcanoes exist because of the rigid plates in the Earth’s crust. There are sixteen major plates that float on a softer layer of rock in the Earth’s mantle. Most volcanoes occur near the edges of plates.
Sometimes when plates push together,
one plate slides beneath the other. This is called a subduction zone. When the plunging plates get deep enough inside the mantle, some of the rock on the overlying plate melts and forms magma that can move upward and erupt at the Earth’s surface.
At rift zones, where plates are moving apart, magma can reach the surface and erupt. Some volcanoes occur in the middle of plates at areas called hot spots—places where magma melts through the plate.
These Guys Must Be on Steroids!
Repeated eruptions cause volcanoes to grow. There are three main shapes of volcanoes based on the stuff that comes out of them when they erupt.
Stratovolcanoes are built from eruptions of lava and tephra that pile up in layers like cake and frosting. They form volcanoes with symmetrical cones and steep sides.
Cinder cone volcanoes are created by erupting lava that breaks into small pieces as it blasts into the air. As the lava pieces fall back to the ground, they cool and harden into cinders that pile up around the volcano’s vent. Cinder cones are very small, cone-shape volcanoes.
Shield volcanoes are formed by eruptions of flowing lava. The lava spreads out and builds up volcanoes with broad, gently sloping sides. The shape resembles a warrior’s shield.
Here Are a Few of the Most Famous Volcanic Faces!