Site hosted by Angelfire.com: Build your free website today!

Thunderstorms - Basic explanation

 

Thunderstorms
Lightning - photograph

 

At any moment throughout the world, there are nearly 1,800 thunderstorms occuring. The average number each year is 16 million. When compared to tornadoes, hurricanes, etc, the area of a thunderstorm is relatively small at an average of 15 miles in diameter, and a life of around 30 minutes. The most dangerous elements of any thunderstorm are it's by-products of flash floods, hail, lightning, lightning induced fires, high winds, and tornadoes. In the last 10 years in the USA, 15,000 lightning induced fires have occured at a cost of several million dollars, and the loss of 2 million acres of forest.

 

 

USA - Wisconsin

 

4th July 1977 - The severe thunderstorm that moved across northern Wisconsin, caused extreme damage to trees and properties. Many counties were affected by the severe storm.

Sawyer County - the damage that covered an area up to 17 mile wide 166 mile long, was described by some as being like an oversized tornado. In fact, it was the downburst winds up to 135 mph of the thunderstorm that caused the damage. Large areas of the Flambeau State Forest, including trees four feet in diameter, were flattened. One person was killed, and eight injured.

Price County -in Phillips City, thirty homes were destroyed and almost all the buildings in the area sustained damage. Phillips airport recorded winds in excess of 100 mph. The aftermath in Price County was, twenty people injured, and 172,000 acres of forest destroyed or badly damaged.

Oneida County - winds in excess of 100 mph were reported at the Rhinelander airport. Seven people were injured, eight homes were badly damaged, and 200,000 acres of forest sustained damage.
The ferocious storm resulted in over $24 million in damage (1977 dollars), one death and 35 injuries.

 

USA - Ohio

 

1969 - Northern Ohio suffered severe thunderstorms with winds over 100 mph and very heavy rains. From 4 to 15 inches of rain fell from late evening into the next morning producing major flash flooding. Over 40 people were killed, almost 600 injuried, and the total damage exceeded $66 million.

 

Australia - Sydney

 

18th March 1990 - a violent hailstorm moved across the Sydney area affecting both sides of the harbour. The most seriously damaged areas being in Auburn and Bankstown. The driving hail damaged thousands of houses, which sustained broken windows and damage to roofs. In some areas, every house in the street suffered damage. The largest hail produced by the storm occurred in the southwestern suburbs, where reports of hail up to 8cm in diameter had been seen. A number of violent wind squalls and heavy rain were also reported.
The State Emergency Service received more than 3,500 calls for help in the first two days after the storm. Units had to be brought in from other parts of Sydney and the Newcastle, Illawarra, Central West and Queanbeyan-Cooma areas.
The insurance payout for the storm exceeded $384 million.

 

 

Australia - Sydney

 

14th April 1999 - the intense thunderstorm that moved over Sydney's suburbs produced a deluge of enormous hailstones. The largest measured hailstone had a diameter of 9 cm (3.1/2 in). It was said that the more severely-damaged areas suffered from even larger stones. In the worst hit suburbs of Kensington and Eastlakes, there were many streets with damage to every home. Over 20,000 properties, 40,000 vehicles, and more than 25 aircraft at Sydney Airport, were damaged.
This hailstorm was of a magnitude seldom seen in Australia, or the world, and stands as Australia's most costly to date, with insurance claims exceeding $1.5 billion dollars; and the storm only lasted for one hour.

 

 

Other Famous Thunderstorms
 

 

Australia - Northern Rivers

 

16th. January 2002 - a severe thunderstorm developed near Grafton and tracked to the northeast causing damage near Casino and Lismore. The cell didn't reach its full ferocity until it neared the coast where reports of hailstones the size of grapefruit, flash flooding and a tornado combined to devastate the towns of Kingscliff and Banora Point.

 

Australia - New South Wales

 

18th December 1998 - severe thunderstorms affected the Mid-North Coast and Northern Rivers weather districts, with winds in excess of 122 km/h. Various sizes of hailstones were reported throughout the area, the sizes being described as - cricket ball, golf ball, apple and mandarin size. Maximum hail sizes reported at Evans Head was measured at 5.25cm. Flash flooding and much wind damage was reported by Storm Spotters in the area. In the Tweed and Clarence Valleys, 6 houses were unroofed and many others were damaged. At Murwillumbah three houses lost their entire roofs and up to 100 others had roof damage. Numerous trees were uprooted and fell across roads and houses. The industrial area was badly damaged, and at the airport, a light plane was destroyed and three more were damaged.

 

England - London

 

14th August 1975 - August started with a large anticyclone enabling a weak southerly airflow, which led to temperatures of 30C that day in London . On the 14th a week cold front moved east, and at 5pm a violent thunderstorm broke out over Hampstead. Later to be labeled "The Hampstead Storm", this was one of the most notable thunderstorms of the century. It was what is known as a "supercell storm". 170.8 mm of rain fell in 2.5 hours at Hampstead, with hail as large as 16 mm. This was one of the highest rainfall rates of the twentieth century. One person drowned, streets became canals with cars floating down them. The Underground was flooded, and rail services were disrupted for 24 hours. Just 4 miles away, in the City, there was no virtually no rain to be seen.

 

Myth: The rubber soles of shoes or rubber tyres on a car will protect you from being struck by lightning.

Fact: Rubber-soled shoes and rubber tyres provide NO protection from lightning. However, the steel frame of a hard-topped vehicle provides increased protection if you are not touching metal. Although you may be injured if lightning strikes your car, you are much safer inside a vehicle than outside.

 

 

Straight-Line Winds are responsible for most thunderstorm wind damage. The downburst, which is a strong downdraft (descending air inside a thunderstorm) Can exceed 100 mph!. This hits the ground and fans out, causing damage equivalent to a strong tornado.

 

 

 

Back to Fizzy's office
Test yourself on this subject
Office
Quiz

fizisist@yahoo.co.uk