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Hail, Sleet, and Ice Storms

by Kevin Lin

Pictures of some really big hail

Hail

Hail is precipitation that comes in the form of lumps of ice that form in storms. They are usually round, and vary in size. The layered structure of hail is produced by successive accretions of clear and frothy ice. The hailstones grow as they are held up by winds. Smaller hail is the size of a pea, and bigger hail can be as a big as a grapefruit. The usually form in thunderstorms that are between the updraft and the downdraft. The updraft is the current of rising air that carries supercooled water, and a downdraft is a current of air descending toward the ground. When a raindrop is captured in an updraft it moves to higher levels of the cloud where the temperatures, even on the hottest summer day, are well below freezing. The raindrop freezes and falls through the cloud. If the now-frozen pellet (sleet) is again captured by an updraft, it will receive a new coating of ice. This process may be repeated a number of times until the hunk of ice is simply too big to be taken aloft by another updraft, and it finally falls to the ground. If a small ice pellet is not recaptured by an updraft, it will likely melt before it reaches the ground.The larger the hail stones are, the stronger the updrafts.In the summer, only the largest hail can survive the warm temperatures in the lower atmosphere. If you were to cut through a piece of hail, you would probably see a number of distinct layers or concentric rings of ice. One of the largest chunks of hail ever seen fell in Coffeyville, Kansas on September 3, 1970. It had a diameter of almost six inches, and it weighed about 1.67 pounds!

Hail storms cause a huge amount of damage to property and crops across the United States every year. In 1993 and 1994, hail storms alone caused 500 million dollars in damage. Fortunately, very rarely kills people. The last know hail related death in the United States was an infant killed in Fort Collins, Colorado, in August of 1979. However, dozens of people are injured every year. Deaths and injuries are more common in other parts of the world, especially places where many people live in poorly constructed buildings.

Hailstorms are most common on the Plains and Midwest area, especially just east of the Rocky Mountains. Hail storms are common in the midwest because that is where most thunderstorms take place. Other parts of the world that have damaging hailstorms include China, Russia, India and northern Italy.

Dangerous Hailstorms

On September 3, 1970, in Coffeyville, Kansas, the largest recorded hailstone fell. It measured 17.5 inches in diameter, and weighed 1.67 pounds.
In May of 1995, the costliest thunderstorm in American history struck the Fort Worth/Dallas Metroplex. It caused one to two billion dollars in damage, and most of the damage was due to hail and flooding.

Safety Tips

Seek shelter immediately, because if one of the hailstones hits you, you will be hurting for certain.
If you are driving, pull over until the hailstorm stops, because the hailstones might crack your windows.

Sleet

Sleet is a wintertime phenomena and refers to the fall of small, clear to translucent particles of ice. For sleet to be produced, a layer of air with temperature above freezing must overlie a subfreezing layer near the ground. When the raindrops leave the warmer air and encounter the colder air below, they solidify, reaching the ground as small pellets of ice no larger than a raindrop.

Sleet helps form Ice Storms

On some occasions, when the vertical distribution of temperatures is similar to that associated with the formation off sleet, freezing rain or glaze results instead. In such situations, the subfreezing air near the ground is not thick enough to allow the raindrops to freeze. The raindrops, however, do become supercooled as they fall through the cold air and consequently turn to ice upon colliding with solid objects. The result can be a thick coating of ice that is sufficiently heavy to break tree limbs and down power lines as well as make walking or motoring extremely hazardous.

Safety Tips

Seek shelter!
Cover up all exposed body parts!

Deadly Sleet Storms

Look under ice storms!

Ice Storms

An ice storm, also known as glaze storms, is actually freezing rain on a larger scale. Freezing rain or drizzle produced when temperatures at the surface area are below freezing. The rain or drizzle falls in the liquid state, but freezes on contact. As the rain accumulates and freezes on contact, a coat or layer of ice is formed. When the layer of ice glaze reaches a substantial amount, it is considered an ice storm. There is no official number of centimeters or inches that changes the freezing rain into an ice storm. Another name for an ice storm, is glaze.

How Ice Storms Form

The formation of an ice storm, is very similar to that of sleet. The first thing that happens, it the formation of rain but the collision-coalescence process. Then, the conditions of the air temperature close to the surface have to be just right. A layer of air below freezing has to lie near the ground. Above that, there must be a layer of air just above freezing. As the raindrops fall, the layer of air below freezing is not thick enough to cause the drops to solidify into little ice pellets. Therefore, instead of little frozen raindrops, supercooled raindrops are formed. Supercooled means that the droplets of water have temperatures below freezing, but have not solididfied into the state of ice. This usually occurs because the droplets lack either freezing nuclei or pressure. Freezing nuclei is just particles that are needed for the formation of ice particles. When the supercooled raindrops are formed, the rain or drizzle starts to freeze on contact. Whenever these little drops of supercooled water collides with another object, a little bit of ice is added to it. The ice that usually forms, ranges from a thin coating , to about an inch. When accompanied by powerful winds, these storms can cause tremendous damage to trees, electric wires, and telephone lines. What occurs, is that the ice accumulates, and becomes very heavy. Then, the winds help break off tree branches or sometimes even blow down telephone lines. But, the biggest reason that ice storms are so dangerous is due to an indirect effect. It is a fact that 85 percent of he deaths that occur during an ice storm are traffic related. Many times, streets and highways form a coating of ice which makes travel extremely difficul and hazardous for people stuck in the storm. Freezing rain, is usually produced between the formation of rain an dsnow. Therefore, it acts as a transition between the types of precipitation.

Factors needed for Ice Storms to form

There are two factors needed to produce ice storms. They are: moist air/moisture, and cold air. Without moist air, no clouds can form to produce precipitation. For air to rise to form clouds, there has to be either a cold front which comes along to force warm air upward, or a warm front which comes along, and is force upward by a cold front. The lift of war m air occurs because cold air is more dense than warm air. The less dense air then rises above. The other factor, cold air, is needed to lift the moisture in the air. Both of these factors are needed to produce ice storms.

Where do Ice Storms Occur?

Ice storms can occur anywhere just as long as the conditions are right. But, the places where they occur most are in Nebraska, Kansas, Oklahoma, the New England states, and the mid-Atlantic region. This occur here most often because these regions often have two fronts clash which causes different types of winter storms. Ice storms are one type of winter storms that occur, but not very often.

This unusual, but destructive phenomenon is unknown by most people, because many serious ice storms don’t occur very often. But, it is smart to learn about them because this kind of storm could kill very easily.

Devastating Ice Storms

The most devastating Midwest ice storm was in 1922 between February 21 to February 22, freezing rain hit Wisconsin and power lines had ice that built up to four inches in diameter. Although there was only one death, damages came out to about ten million dollars.
From January 7 to January 9, 1973, Atlanta, Georgia, was hit hard by freezing rain. It was measured that four inches of freezing rain fell causeing damages to be twenty five million dollars. This ice storm force many businesses and schools to close for many days and stopped most of the traffic.
An ice storm that hit Mississippi on February 9, 1994, affected areas from Arkansas to Maryland. For three weeks, several thousands of homes did not have power. This storm left many splintered power poles, broken limbs and snapped trees.
The most devastating thunderstorm in United States history was one that struck many southern states form January 28 to February 4 in 1951. In Mississippi alone, there was about 50 million dollars in damage. In Louisiana, it was 15 million, and about 2 million in Arkansas. The storm also ended up killing 22 people. On February 2, Tennessee as hit by this storm. It was badly damaged with costs up to 1 million dollars, and caused the power and telephone to go out for about 7 to 10 days.

Safety Tips

If driving in a vehicle

If you don’t have snow tires on, install chains for better traction.
Try not to use parking brakes, as they might freeze.
Use a non-freezing window washer so sheets of ice don’t form.
Use antifreeze to prevent engine from freezing, and don’t use the heater because there may be a carbon monoxide buildup.
Turn on defroster to keep windows clear.
Before turning, give signals earlier for safety.
Drive slow and accelerate slowly so there’s no skidding.
Before going up a hill, build up speed to prevent sliding down.

If caught outside

Try to seek shelter.
Keep all exposed body parts covered.
Wear loose-fitting layers so clothing can trap heat.
Stay away form any electric wires that are down
Walk carefully since ground can be slippery.

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