Thursday Thirteen #6 - Tornadoes

Living in Kansas the threat of tornadoes is similar here as the threat of earthquakes are to California, or Hurricanes to Florida. While I’ve known about them all my life, I can’t say that I’ve really KNOWN about them (i.e. I’m probably not as afraid of them as I should be!), so I thought I’d do a little reading and share a few facts for my Thursday Thirteen this time.

If you don't want to wade through the actual 13, at least skip to the videos at the end, they're amazing!


1. What is a tornado? A tornado is a violently rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris.

2. Where do they happen? Although tornadoes have been observed on every continent except Antarctica, most occur in the United States. They also commonly occur in southern Canada, south-central and eastern Asia, east-central South America, Southern Africa, northwestern and southeast Europe, Italy, western and southeastern Australia, and New Zealand.

3. Here is an interesting list of the tornadoes and tornado outbreaks in North America from pre-1900’s through just a few days ago.

4. While there is no single agreed upon definition, generally more than six tornadoes in a day in the same region is considered a tornado outbreak. The largest on record, dubbed the Super Outbreak, was April 3-4, 1974 with 148 tornadoes of varying intensities (F-scale ratings).

5. The F-Scale, or Fujita Scale is a scale for rating tornado intensity, based on the damage tornadoes inflict on human-built structures and vegetation. These ratings are F0 through F5. F0 tornadoes have winds of around 40-72 mph and cause light damage, while F5 tornadoes have winds of around 261–318 mph and can cause incredible damage. 93.9% of tornadoes fall into the F2 category and below. Less than .1% of tornadoes are F5’s thank goodness, but even that % is way too high for my liking!

6. In 2007 the Enhanced Fujita Scale went into use. It was revised to reflect better examinations of tornado damage surveys, so as to align wind speeds more closely with associated storm damage. Better standardizing and elucidating what was previously subjective and ambiguous, it also adds more types of structures as well as vegetation, expands degrees of damage, and better accounts for variables such as differences in construction quality. The first time the EF5 rating was used was for the Greensburg, KS tornado that occurred on May 4th, 2007. See a picture of the damage from this one Here

7. In an average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500 injuries.

8. What causes a tornado? A tornado generally occurs when high winds within a low pressure system (such as a thunderstorm) cause water vapor in the air to condense in to a condensation funnel cloud.

9. Tornado Frequency In the southern states, peak tornado occurrence is in March through May, while peak months in the northern states are during the summer.
Note, in some states, a secondary tornado maximum occurs in the fall.

Tornadoes are most likely to occur between 3 and 9 p.m. but have been known to occur at all hours of the day or night.

The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction. The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.

The total number of tornadoes is probably higher than indicated in the western states. Sparce population reduces the number reported.

10. Tornado Myths:

MYTH: Areas near rivers, lakes, and mountains are safe from tornadoes.
FACT: No place is safe from tornadoes. In the late 1980's, a tornado swept through Yellowstone National Park leaving a path of destruction up and down a 10,000 ft. mountain.

MYTH: The low pressure with a tornado causes buildings to "explode" as the tornado passes overhead.
FACT: Violent winds and debris slamming into buildings cause most structural damage.

MYTH: Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
FACT: Opening windows allows damaging winds to enter the structure. Leave the windows alone; instead, immediately go to a safe place.

11. HERE is a collection of tornado photos, #16, is the oldest known photo of a tornado, it just looks evil!

12. John Brosio is an artist that has done many works featuring tornados.

13. When it rains, it pours, and sometimes, it pours frogs? Check out this article from the BBC.

Here are a couple of videos, I think of the same tornado from different people, I think these guys are certifiable!!! But they are fascinating...

This one is very long, but some amazing footage of it from beginning to end



And these guys, I don’t know, if I’d driven up next to that… I don’t even know what to say!




http://en.wikipedia.org/wiki/Tornado
http://www.nssl.noaa.gov/edu/safety/tornadoguide.html
http://www.livescience.com/tornadoes/
http://www.tornadoproject.com/tornproj/tornproj.htm#top