Interesting Storm Facts.

[Jane Louise]

What type of cloud produces thunderstorms?

The cumulonimbus (Latin, for “rain heapsâ€) is the massive cloud factory which spawns lightning and thunder. This cloud can span the depth of the troposphere, with its base near the group, to its icy characteristic “anvil†top, sometimes more than 12 miles high. In extreme storms, updrafts can reach 100 mph. Downdrafts can often attain even greater speeds. Aircraft avoid the cumulonimbus due to the extreme turbulence often found inside.

What are the â€four horsemen†of thunderstorms?

Floods, hail, lightning and wind/tornadoes. All are spawned by thunderstorm clouds, sometimes all at the same time. The cumulonimbus cloud is an amazingly efficient weather factory.

How high do thunderstorm go?

Almost all thunderstorm clouds grow to heights above 20,000 feet. With 35,000 feet being typical. The more intense ones continue upwards until they hit the top of the troposphere, called the tropopause. Since penetrating into the stratosphere takes a lot of energy, many cumulonimbus clouds flatten out on the tropopause into the classic anvil shape with the tip streaming off downwind. If the storm is unusually intense, the updraft may punch into the stratosphere in cauliflower-like turrets. These “trop busters†are usually severe storms, with internal updrafts perhaps exceeding 100 mph. At any given place and time the height of the tallest storms is thus controlled by the height of the troposphere.

The air mass thunderstorm is perhaps the most common. It is relatively small and short lived and forms in semi-random patterns within large, moist high pressure systems. Sea breeze thunderstorms are indicative of their triggering mechanism, as are cold frontal storms. Squall lines are long thin chains of storms, which on occasion have been known to extend for more than 1000 miles along or ahead of cold fronts. Larger, non-frontal thunderstorms are often called mesoscale convective systems or, the biggest of them all, the mesoscale convective complex (MCC). These monsters can be the size of several eastern states and live for twelve hours or more. Supercells, which often rotate as a whole, are often relatively small in size but long lived, often producing tornadoes and major hail storms. Sometimes these cells split into two pairs, one moving to the right and the other to the left.

What is a downburst and a microburst?

Inside a thunderstorm there are powerful updrafts and, as a the storm matures, downdrafts (what goes up does come down). The updrafts can reach many tens of miles per hour. Turns out storm downdrafts can be equally as intense. The downdrafts are caused by factors such as the drag from heavy masses of rain and hail, and especially the fact that falling precipitation evaporates and cools the air, making it heavier than its environment. Most thunderstorms generate downdrafts, the cooling, outward rushing air that often breaks the heat of any oppressively hot summer afternoon. The leading edge of the downdraft is called the gust front. It is sometimes marked by spectacular cloud features called shelf or roll clouds. But on some occasions, downdrafts can become locally very intense, slamming into the surface with wind gusts well in excess of hurricane force. That is a downburst. The smallest of these are called microbursts, some of which may be only several hundred yards across. Recent research has shown that much storm damage once ascribed to tornadoes is actually the result of microbursts. Their winds can equal that of small tornadoes and, to the untrained eye, the damage looks as if a tornado went through. They can also be accompanied by very loud roaring noises. The second greatest cause of aircraft accidents, after pilot error, are the extreme wind shears associated with thunderstorm downburst winds. Since 1964, at least 29 major airline accidents have been caused by downbursts.

How many thunderstorms occur each year?

Nearly 2000 thunderstorm cells are estimated to be present over the planet at any given time. It is estimated that globally there are 16 million thunderstorms each year.

The most damaging hailstorm ever?

It would appear that Munich, Germany holds that dubious distinction. In 1984 a massive hailstorm caused at least $1 billion in damages. A hailstorm pounded the Colorado Front Range, including the City of Denver, on 11 July 1990. The resulting property losses were at least $625 million. Forty seven people were injured at an amusement park, some seriously, when a power failure trapped them on a Ferris wheel and they were battered by softball-sized hail. They were not amused. A 1995 hailstorm in the Dallas-Ft. Worth area is reputed to have been even costlier.

From the truly strange weather log book:

In December, 1933, huge hailstones were reported to have fallen around Worcester, MA-containing fresh, frozen ducks inside. Daffy weather, indeed

A thunderstorm that occurred in Germany on 9 August 1892 resulted in a heavy fall of rain...and hundreds of fresh water mussels .

A thunderstorm near Vicksburg, MS in 1930 resulted in some rather interesting hailstones. One had a solid piece of alabaster 3/4 inch across. Another was a live 8" long gopher turtle, entirely encased in ice.

Bucharest, Romania reported a rainstorm on 25 July 1872. But along with the rain fell myriads of small black worms that littered the streets.

On 17 July 1841, a shower of heavy rain and hail in Derby, England was accompanied by hundreds of small fish and frogs, many of them very much alive.

Scientific American, in 1877, reported that a rain of snakes, some up to 18 inches long, fell over the southern part of the city of Memphis, Tennessee.

A new form of cloud seeding? In 1687, hail fell in England containing the seeds of ivy berries.

Toads.Toads.Toads. In 1953 the town of Leicester, MA was deluged by a fall of toads. Children were able to gather them up by the bucketful.

The term hailstone is a bit of a misnomer since no “rocks†are involved. However, in Sweden in 1925 a large chunk of limestone did fall from the sky, smashing into myriad pieces upon impact.

A peach of a storm. In 1961, a portion of Shreveport, LA was pelted by small, unripe peaches during a passing thunderstorm.

In Spain, in 1902, a rain shower was observed in which the rain drops, upon touching the ground, gave off a crackling noise and emitted electrical sparks. The event lasted for less than ten seconds.

http://www.sky-fire.tv

[Jane Louise]

Comma Cloud

This term refers to the typical cloud pattern of a midlatitude cyclone (especially winter storms) when viewed in satellite images. The curvature of the cloud system is like that of a comma because of the counterclockwise rotation of winds that occurs with a strong low pressure system. Visually, a sharply curved cloud system, usually indicates a deep low pressure center and a strong storm.

Derecho (day-ray cho)

"Derecho" is a Spanish word for "right ahead" or "straight ahead." It has become a severe weather term used to describe a windstorm which accompanies a large mesoscale convective complex (MCC) such as the one which crossed the state on July 1. These winds can be long-lived and very destructive as they move along with squall lines and thunderstorm systems. They are part of the family of downburst winds, often quite cool in terms of temperature. Their destructive pattern tends to be different than tornadic winds in that they scatter debris in a narrow vector rather than in all directions. The most severe recent episode of derecho winds was in July of 1995, when over 6 million trees were damaged or destroyed along a wide path in northern Minnesota.

Dog Days

The "dog days of summer" are usually associated with the greatest heat of the year, characterized by thunderstorm activity and high dew points. The origin of this term is both ancient and astrological:

When Sirius rising with the sun

Marks the dog days well begun

Four Basic Thunderstorm Types

Thunderstorms occur in a variety of forms, sometimes as an isolated cumulonimbus cloud (anvil shaped), sometimes as a cluster of clouds, sometimes as a squall line, and sometimes as a supercell (massive convective cloud system). The first type is known as a single cell storm usually composed of a convective cloud containing one updraft and one downdraft segment. These may produce some heavy rain, hail, or even a weak tornado, but they are usually short-lived (30 minutes or less). The second type is known as a multicell cluster composed of a group of convective clouds that move together as a single unit. There may be multiple updraft and downdraft segments, highly variable rates of rainfall, and some moderate hail. These systems may last for hours and produce flash flooding or weak tornadoes. The third type is the squall line composed of a line of convective clouds which share a common gust front along the leading edge (sometimes seen as a wall cloud). They can move at rapid speeds and produce heavy rainfall and moderate hail, sometimes resulting in flash flooding. Tornadoes may occur behind the squall line as well. The fourth type of thunderstorm is the most damaging, that is the supercell, which is composed of a system of clouds which rotate as one unit containing imbedded strong updrafts and downdrafts, large hail and frequent lightning. These can produce flooding and moderate to severe tornadoes

Fulgurite

This word is used by both geologists and meteorologists. Derived from the Latin root word "fulgur", meaning lightning, this is a term used for the glassy, rootlike tube that is formed when lightning strikes a sandy soil. The intense heat causes soil moisture to vaporize, and the remaining molten material fuses into a tube-like sturcture which may be an inch or two in diameter and inches to several feet in length. The wall-like material holding them together is very thin and fragile,

Heat-burst

Like a downburst from a thunderstorm which brings destructive winds, a heat-burst sometimes occurs as a result of sinking motion within the downdrafts of thunderstorms. It is not destructive, but it does bring a rise in temperature as a result of compressional heating (rising air cools, falling air warms)

Heat Lightning

This term was derived from observations of lightning under clear skies during warm summer evenings. It was misconstrued that the lightning was produced by an excessively heated atmosphere. Technically all lightning produces heat, since a single stroke can heat the surrounding air to over 50,000 degrees F, causing sound waves due to the rapid expansion of air, which we later hear as thunder. Sound travels approximately a mile every 5 seconds, so you can gage the distance of the lightning flashes by counting how many seconds pass between the flash and the resulting thunder (approximately 1/5 of a mile for every second). Thus a 15 second interval between observed lightning and the sound of thunder indicates that the flash occurred about 3 miles away. Lightning strokes from over 10 miles away are rarely heard as thunder.

Mesoscale Convective System (MCS)

This expression, often used by the National Weather Service, refers to a cluster of thunderstorms which is larger in scale than any individual cumulonimbus cloud, but smaller in scale than a frontal system. These systems appear on satellite imagery as circular or linear cloud forms with very bright tops (indicating cold air). Often times severe weather including, hail, damaging winds, heavy rainfall and tornadoes are associated with an MCS.

Nephoscope

This term is derived from the Greek words nepho, meaning "cloud," and scope, meaning "to view." A Nephoscope is an instrument for viewing clouds and determining their motion. There are two types of Nephoscopes: one with a direct view and one with a mirror view of the sky. Each instrument allows the observer to determine the compass direction in which clouds are moving. Cloud motions may vary with elevation; that is, low clouds may be moving in one direction and high clouds moving in another.

Renegade showers

This is how meteorologists often refer to isolated thunderstorms and showers that have broken away from a major complex of thunderstorms or a large frontal system. Often times these clouds escape from the main air flow aloft and may linger over areas of the landscape already saturated by the earlier passage of strong thunderstorms. They typically only effect small areas ranging up to less than 100 square miles. The use of the Spanish term renegade connotates a hostile deserter from the main band of active weather.

SIGMET

This is an acronym for significant meteorological observations used in aviation forecasting. When significant events are observed or forecast a SIGMET is ussued to help pilots plan routes and anticipate conditions. A SIGMET might refer to thunderstorms, icing levels, severe clear air turbulence, volcanic smoke plumes, or other features which affect visibility or aircraft performance.

http://climate.umn.edu/weathertalk

[in the vale]

Thanks for posting that info, JL. Very informative! Esp. the gopher turtle and the ducks!

[Jane Louise]

Thanks for posting that info, JL. Very informative! Esp. the gopher turtle and the ducks!

Hi in the vale,

I'm glad you enjoyed reading it.

Stay tuned, there's more to come later.....

[Jane Louise]

The biggest hailstone recorded weighed 2 1/4 pounds.

In January 2000, Spain came under attack from an unknown assailant. Giant chunks of ice dropped from cloudless skies and crushed car hoods, punched through rooftops and windshields, and slammed into the shoulder of an elderly woman. In a 10-day period, 15 basketball-sized ice balls weighing up to 8 pounds pelted southern Spain.

In March 1991, there were more than 15,000 lightning strikes in a six-hour continuous storm that raged over Iowa, Wisconsin, Illinois and Missouri. During that time, the skies had constant lightning. The Empire State Building, in New York City, gets hit by lightning almost 23 times a year.

A particularly deadly lightning incident occurred in Brescia, Italy in 1769. Lightning struck the Church of St. Nazaire, igniting the 100 tons of gunpowder in its vaults; the resulting explosion killed 3000 people and destroyed a sixth of the city.

Superstition states that putting an acorn on a windowsill during a thunderstorm protects the occupant's home from a lightning strike. Even modern blinds reflect this with acorn shaped pulls being quite common.

[Stuart]

Thanks for that Interesting Storm Facts Jane

[Jane Louise]

Thanks for that Interesting Storm Facts Jane

You're welcome Stu, will find more to post up soon.

[Coast]

Just checking the news this morning about our storms yesterday, I came across this interesting article from the States.

When it comes to lightning, females are cautious and males are reckless. The result: Between 1995 and 2008, lightning killed 648 people, and of those, 82 percent were male, according to AccuWeather.com.

"Men take more risks in lightning storms," said John Jensenius, of the National Weather Service, adding that males are less willing to walk away from recreational activities or sports. Indeed, those pastimes are involved in almost half of all lightning-related deaths, according to Popular Science. Florida sees more thunderstorms and lightning than anywhere else in the United States, with South Florida, Tampa Bay and the Interstate 4 corridor near Orlando tied for seeing the most bolts per year, the weather service said. For instance, Tampa Bay once recorded up to 50,000 flashes in June alone. While there have been no local deaths this year, lightning has so far killed six people nationwide, all of them male. Among them: A 26 year-old-man, playing baseball in Ruby, S.C., on June 21, and a 49-year-old man, golfing in Shreveport, La., on June 7.

Since 1959, lightning has killed 94 people in Broward, Palm Beach and Miami-Dade counties, or an average of about two per year. On average, another 10 are injured each year. Most of the deaths, more than 70 percent, occurred during June, July and August. In Central Florida, from Tampa Bay to Melbourne, more than 110 people were killed in the same time period. The last: A young man was killed in Melbourne Beach in July 2009, the weather service said. On July 4, 2009, in Polk County, lightning struck in a field as a church group was in the middle of a soccer game and picnic. One man died, 18 were injured. In July 2007, in Pinellas County, lightning struck a 16-year-old boy and his mother, while they were on Treasure Island Beach. The bolt hit the boy in the chest, knocking him unconscious. He died four days later. The mother was not seriously injured.

While no one was killed, last September a bolt struck a light post shortly after the start of a high school football game inOrange County, sending two people to the hospital and prompting a chaotic evacuation of the metal stands. The most recent South Florida lightning deaths: A 37-year-old man was struck while standing in a 14-foot aluminum boat in Biscayne Bay in Miami in September 2009. In June 2009, landscaper Dessalines Oleus, 53, of Pompano Beach, was struck as he was mowing a lawn inCoral Springs. In August 2003, two Palm Beach County men were struck on the same day at their homes, one in Delray Beach as he trimmed his lawn and the other in his driveway near Boca Raton. Statewide, lightning kills an average of 10 people and injures an additional 30 per year. Only rip currents are a more prolific weather-related killer, claiming 20 to 25 lives per year statewide.

Those aged 10-19 are struck more than any other age group, as school is out and children frequently play outside, the weather service said. The last person to be struck in South Florida was Joseph Guerrero, then 17, who was fishing on the bank of a lake near Lake Worth in August 2010. He has since recovered. Lightning is expected to flash most afternoons this week across the state, with the weather service predicting a 40-60 percent chance of storms through Friday.

Forecasters stress thunderstorms can shoot lightning up to 10 miles from their cores, even into areas where there might not be rain. "The common perception is lightning happens only when it's really dark and stormy out," said meteorologist Robert Molleda. "But lighting can travel a pretty good distance from where the rain is falling."

http://www.latimes.com/news/nationworld/nation/wire/fl-most-lightning-deaths-male-20110627,0,3530715.story

[Snowangel-MK]

Just checking the news this morning about our storms yesterday, I came across this interesting article from the States.

"Men take more risks in lightning storms," said John Jensenius, of the National Weather Service, adding that males are less willing to walk away from recreational activities or sports. Indeed, those pastimes are involved in almost half of all lightning-related deaths, according to Popular Science.]

Edited June 29, 2011 by MKsnowangel