Tornadoes

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The funnel of a tornado is formed by moisture in the air that is cooled and condensed by the tornado's low pressure. Temperatures at higher altitudes are generally cooler, making it easier for the moisture to condense, which makes for a funnel that is wider at the top.

There are various factors that are not fully understood. Part of it has to do with how much energy a storm can put into producing a tornado, as it takes more energy to move a larger amount of air and large tornadoes tend to be stronger. This depends both on how strong the thunderstorm is and how it is organized (i.e. where energy goes and in what forms). A well organized supercell thunderstorm with a lot of energy can produce very large violent tornadoes. Additionally, a key part of tornado formation occurs when a larger circulation, called a mesocyclone , tightens and intensifies. A mesocyclone that is not tightened as much may result in a large but not particularly strong tornado.

The wind speed ranges for the levels of the Fujita scale are listed below. However in the 21st century it was found that these wind speeds, which were just estimates, were inaccurate for the damage levels that were the basis of the ratings, especially for stronger tornadoes. The corresponding winds of the more accurate enhanced Fujita scale are given in parentheses. Although the wind estimates are different, the damage by each category done is essentially the same.

F0: 40-72 mph (EF0 65-85 mph)

F1: 73-112 mph (EF1 86-110 mph)

F2: 113-157 mph (EF2 111-135 mph)

F3: 158-206 mph (EF3 136-165 mph)

F4: 207-260 mph (EF4 166-200 mph)

F5: 261-318 mph (EF5 over 200 mph)

The funnel cloud of a tornado is full of water droplets just like an ordinary cloud. As a result it blocks light and may appear dark. A tornado may also appear dark if it is lifting large amounts of dark soil into the air. However, not all tornadoes are dark in color. Front-lit tornadoes may appear light gray or even white. Depending on the soil some tornadoes may be light tan, to reddish brown, to gray in color.

As with just about all places that tornadoes strike the damage varies widely depending on how strong the tornado is and exactly where it hits. Since South Dakota is mostly rural most tornadoes cause little to no damage as they don't hit much. However a strong enough tornado could still easily level a few farms. In some cases a weak tornado strikes a town, causing minor to moderated damage. In rare cases, though a large, violent tornado can strike a community and cause utter devastation.

Tornadoes are very dangerouswith there wind speeds and they can kill people in a snap of a finger.

The main reason is that the Philippines are tropical while much of the U.S. has a temperate or subtropical climate. In a climate such as that of the U.S. there are greater temperature contrasts which leads to stronger thunderstorms. Particularly in the spring and early summer when the lower atmosphere is relatively war while the upper atmosphere is relatively cold the atmosphere becomes very unstable. This, accompanied by strong fronts and often a dry line can ignite violent thunderstorms capable of producing tornado, some of the very strong.

By contrast in a tropical area such as the Philippines the atmosphere is relatively warm at all levels pretty much year round resulting in a less unstable atmosphere. While some instability does occur and lead to thunderstorms, these storms are often generally strong enough to produce tornadoes.

Additionally, the U.S. is a much larger country than the Philippines and simply has more places for tornadoes to hit.

For the most part a tornado is actually an updraft as it is connected with the rotating updraft of its parent thunderstorm. However there are two downdrafts that are related to tornadoes. The first is the rear-flank downdraft of a thunderstorm. This downdraft is induced by rain and wraps around the rotating updraft of a supercell thunderstorm. This is believed to tighten and intensify the mesocyclone to produce a tornado.

Another, less common downdraft occurs when a tornado undergoes something called vortex breakdown. The center of a tornado has low pressure, which draws air inward and upward, but in a very intense tornado the air is spinning so fast that it cannot reach the center so the low pressure draws air downward, forming a downdraft in the center of the tornado. This is a similar mechanism to what produced they eye of a hurricane.

When you flip the bottle you impart some circulation into the bottle. As water gets pulled in towards the hole at the bottom of the bottle this circulation speeds up through the conservation of angular momentum. The draining water and vortex enhance one another until it forms a "tornado."

As of September 26 there have been 10 confirmed tornadoes in Pennsylvania in 2012.

Oklahoma is more likely to have a tornado. Although New York does get tornadoes Oklahoma has them far more frequently.

It is possible. There is one record of a weak tornado causing minor damage in the Seattle area.

yes

Tornadoes can occur in the U.S. at any time but they are most common in the spring.

The path width of a tornado can vary greatly. Most tornadoes are a few dozen to a few hundred yards wide. However some tornadoes are just a few feet wide. Some tornadoes have damage paths over a mile, and in rare cases, over 2 miles wide.

Yes. Tornadoes hit the U.S. in every month and hundreds hit the U.S. every year. It is inevitable that there will be more. However there is no way of knowing where or when they will hit.

An F4 tornado will completely level well-built houses that are hit by the strongest part of the storm. Weaker structures may be blown away. Bark can be stripped away from trees. In rare cases whole neighborhoods may be flattened.

On averages there are 11 tornadoes in California a year.

Forecasters cannot predict exactly where a tornado will form, but they can detected conditions that lead to them. On long time scales such as hours and days, forecasters look at conditions such as temperature, humidity, and wind shear to determine if tornadoes are likely to form in a region. On time scales of minutes forecasters look for rotation in thunderstorms. If strong enough rotation is detected it means a tornado may form soon or has already developed. Tornadoes generally travel with their parent thunderstorms and so a forecaster can look at what direction a storm is moving to say what areas are potentially in its path.

The last recorded tornado to hit Eau Claire, Wisconsin was on July 3, 1983.

Yes. Tornadoes, regardless of strength, can go over water without being significantly affected. There have been at least 2 cases of F5 tornadoes crossing the Mississippi river.

When you see a tornado, go into a secure building or if there are none near you, huddle in a nearby ditch.

Funnel clouds are the result of rotation in thunderstorms, induced by wind shear, becoming tighter and more intense, stretching toward the ground. If the rotation reaches the ground it is considered a tornado. See the relate question for a more detailed explanation on the formation of tornadoes and the storms that cause them.

The visible funnel itself is a consequence of the pressure drop inside the vortex. Air enterin the vortex experiences a rapid drop in pressure which in turn causes a drop in temperature. This temperature drop causes the moisture in the air to condense into tiny droplets, forming a cloud.