It's Raining Fish and Spiders (31 page)

National Weather Service, National Oceanic and Atmospheric Administration/Department of Commerce
Sydney Oats; used by permission.

National Oceanic and Atmospheric Administration/Department of Commerce

Dust storms have a huge negative economic impact in areas where they remove soil full of nutrient-rich particles, reducing food production. However, dust storms can also be beneficial. In Central and South America, the rain forests get their nutrients from the Sahara. Plus, dust in Hawaii increases plant growth. “I would hang ten, but I've got these plants growing all over my surfboard, dude!”

The Answer, My Friend, Is Blowin' in the Wind

This is an account written by Vance Johnson, who witnessed a dust storm in western Kansas in the 1930s:

What the Hail Is That?

Those really nice warm days of summer can turn out some really nice-size thunderstorms that produce not only torrents of rain, wind, lightning, and tornadoes, but also hail. Yes, ice that falls from the sky, sometimes in amazing sizes. There's pea-, dime-, quarter-, golf ball-, baseball-, and grapefruit-size hail. My favorite is canned-ham size!

That's big!

Hail is not to be confused with sleet. The easiest way to remember the difference is that hail falls in the summer and sleet falls in the winter. Sleet is also a lot smaller than hail.

Hail is formed in spring and summer from tremendous cumulonimbus clouds known as thunderheads. Cumulonimbus clouds harbor a vast amount of energy in the form of updrafts and downdrafts. These vertical winds can reach speeds of over 110 mph. Hail grows in the main updraft, where most of the cloud is formed of what's called “supercooled” water. This is water that remains liquid although its temperature is at or below freezing (32ºF/0°C). A supercooled water drop remains liquid until it encounters something solid on which it can freeze. Ice crystals, frozen raindrops, dust, and salt from the ocean are also present in the cloud. Supercooled water will freeze onto any of these hosts, creating a hailstone or enlarging hailstones that already exist.

Hailstones are usually formed in layers as they bounce around inside the cloud, with supercooled water accumulating and freezing at different rates in different locations. The more supercooled water a hailstone comes in contact with, the larger and heavier the stone is likely to become. When the hailstone becomes so heavy that the updraft can no longer support it, it falls from the sky.

Hail falls along paths called hail swaths, which vary in size from a few square acres to 10 miles wide and even 100 miles long. Hail can accumulate in piles so deep it has to be removed by a snowplow! In Orient, Iowa, in August 1980, hail drifts were reported to be 6 feet (2 meters) deep. On July 11, 1990, softball-size hail fell in Denver, Colorado, and caused $625 million in damage, mostly to automobiles and the roofs of buildings. Forty-seven people at an amusement park were seriously injured when a power failure trapped them on a Ferris wheel and they were battered by softball-size hail.

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