ASK!

Kids ASK! about Science & Technology

To answer your question on what causes greater damage to society: tornadoes or hurricane, you may want to study the extent of damage caused by tornadoes & hurricanes. Tornadoes & Hurricanes are types of very dangerous weather storms that are both capable of tremendous destruction & in some cases even death. Each year these storms cause millions of dollars in damage. This is a highly debatable question & no final conclusion has been reached to which type of storm causing greater damage to society.

Here are some facts on tornadoes:
- Tornadoes are 1 of nature’s most violent storms.
- In an average year, about 1,000 tornadoes are reported across the United States, resulting in 80 deaths & over 1,500 injuries
- A tornado is a violently rotating column of air extending from a thunderstorm to the ground.
- The most violent tornadoes are capable of tremendous destruction with windspeeds of 250 mph or more.
- Damage paths can be in excess of 1 mile wide & 50 miles long.

Tornadoes come in all shapes & sizes & can occur anywhere in the U.S. at any time of the year. In the southern states, peak tornado season is March through May, while peak months in the northern states are during the summer.

Source: NOAA Home Page – Tornadoes

According to USA Today, tornadoes are the most violent storms on Earth.

The National Weather Service defines a tornado as “a violently rotating column of air in contact with the ground & pendant from a thunderstorm. In other words, a thunderstorms is the 1st step in the creation of a tornado. Then, if other conditions are right, the thunderstorm might spin out 1 or more tornadoes.

The 3 key conditions required for thunderstorms to form are:
- Moisture in the lower to mid levels of the atmosphere.
- Unstable air. That is air that will continue rising once it begins rising from near the ground.
- A lifting force. Something is needed to cause the air to begin rising. The most common lifting force is heating of air near the ground. As the air warms it becomes lighter & begins rising. Advancing masses of cool air, which force warm air upward, also trigger thunderstorms.

When all the conditions are present, humid air will rise high into the sky & cool & condense into towering clouds forming thunderstorms. This air rising into a thunderstorms is called an updraft. Tornadoes form in within a thunderstorm’s updraft.

The strongest tornadoes are often near the edge of the updraft, not far from where air is descending in a downdraft caused by the thunderstorms with falling rain or hail. This is why a burst of heavy rain or hail sometimes announces a tornado’s arrival. Tornadoes are often associated with USA’s heartland – in a 10-state area stretching from Texas to Nebraska that also includes Colorado, Iowa, Illinois, Indiana, Missouri & Arkansas, known as Tornado Alley.

But they are not limited to this region. Tornadoes have occurred in all 50 U.S. states & are, in fact, more common in Florida than they are in Oklahoma.

Florida tornadoes are generally weak – for tornadoes – with winds around 100 mph.

Tornadoes that have hit Oklahoma, on the other hand, are some of the most violent on record. A tornado that struck Oklahoma City & its southern suburbs in 1999 had winds of nearly 320 just above the ground.

Tornadoes are ranked by the damage they do using the 6-tiered Fujita Scale. F0 & F1 tornadoes on the scale are considered “weak” & cause minimal to moderate damage with winds from 40-112 mph. F2 & F3 tornadoes are considered strong, packing winds of 113 – 206 mph that can cause major to severe damage. Violent tornadoes are those classified F4 & F5 with winds exceeding 206 mph. Damage is extreme to catastrophic.

Most weak tornadoes last 10 minutes or less, travelling short distances. Violent tornadoes have been known to last for hours & a few have travelled more that 100 miles.

Source: USA Today

Here are some facts on hurricanes:
Hurricanes are cyclones that develop over the warm tropical oceans & have sustained winds in excess of 64 knots (74 miles/hour). These storms are capable of producing dangerous winds, torrential rains & flooding, all of which may result in tremendous damage & loss of life in coastal populations. 1 memorable storm was Hurricane Andrew, which was responsible for at least 50 deaths & more than $30 billion in property damage.

Source: Hurricanes – Online Meteorological Guide

For more information on hurricanes, you may want to refer to these websites:
- National Hurricane Centre
- Weather.com

In 1992, Hurricane Andrew caused massive damage to Homestead, Florida. During the storm, the Benitez family huddled together in a small closet. When the storm finally passed, they had nothing left. But the family survived.

You may want to read their account at this website: What is a hurricane like?

Here are some books that you may want to refer to:

Tornadoes / Nathan Olson.
Mankato, Minn. : Bridgestone Books, c2006.
Call No.: J English 551.55 OLS
Click here for item availability.

Tornado Alert! / Wendy Scavuzzo
New York : Crabtree Pub. Co., c2004.
Call No.: J English 551.55 SCA
Click here for item availability.

Hurricane Hunters and Tornado Chasers / Lois Sakany
New York : Rosen Pub. Group’s Rosen Central, 2003.
Call No.: Y English 551.552 SAK
Click here for item availability.

You can check the availability of these books at our website: http://vistaweb.nlb.gov.sg/index.html

All websites are last accessed on 17th October, 2006.

Answered by Ms Norlizah Mohd Juffri, Librarian, Children’s Services

Found this question interesting? What do you think?
Post your comments, or send further questions about this or any other topic to ask@nlb.gov.sg