What is St. Elmo's Fire?

If you were to look outside your home during a thu­nderstorm and see a tall streetlamp glowing with­ blue flames, you might be tempted to call the fire department. Then you might notice that the streetlamp is on fire but isn't actually burning -- and the water from the fire hose isn't putting out the flames. At this point, you might be about ready to call a priest, but that, like the call to the fire department, would be unnecessary. The phenomenon you're witnessing is actually St. Elmo's Fire. (Which has nothing to do with a 1980s coming-of-age film starring a young Emilio Estevez.)

Brain during orgasm

Although the reasons for having sex of any kind are varied and complex, reaching orgasm is usually the goal. Because we're all so different, coming up with a universal description of an orgasm is impossible. The one thing that most people can agree on is that it's an incredibly, intensely pleasurable experience.

" Merriam-Webster gets more descriptive, stating that it's "an explosive discharge of neuromuscular tensions at the height of sexual arousal that is usually accompanied by the ejaculation of semen in the male and by vaginal contractions in the female." The famous sex researcher Dr. Alfred Kinsey once said that an orgasm "can be likened to the crescendo, climax, and sudden stillness achieved by an orchestra of human emotions ... an explosion of tensions, and to sneezing" [source: Geddes].

Nearly every aspect of the orgasm -- what's required to have one, why some people can't seem to achieve one, why we have them at all -- has been the subject of much research and debate. What happens to the body during an orgasm is pretty well-known, and it's no surprise that the brain plays a big part in reaching one. But researchers are still in the process of figuring out exactly what's happening in the brain during an orgasm. Let's start with looking at the messages that the body sends to the brain.

10 Scariest Bioweapons

Small pox

Smallpox is caused by the variola virus. The most common form of the disease has a 30 percent mortality rate [source: CDC]. Signs of smallpox include high fevers, body aches, and a rash that develops from fluid-filled bumps and scabs to permanent, pitted scars. The disease predominantly spreads through direct contact with an infected person's skin or bodily fluids, but also can be spread though the air in close, confined environments.

In 1967, the World Health Organization (WHO) spearheaded an effort to eradicate smallpox through mass vaccinations. As a result, 1977 marked the last naturally occurring case of smallpox. The disease was effectively eliminated from the natural world, but laboratory copies of smallpox still exist. Both Russia and the United States possess WHO-approved stores, but as smallpox played a role in several nations' bioweapons programs, it's unknown how many secret stockpiles still exist.

T­­he CDC classifies smallpox as a Category A biological weapon due to its high mortality rate and the fact that it can be transmitted through the air. While a smallpox vaccine exists, typically only medical and military personnel undergo vaccination -- meaning the rest of the population is very much at risk if smallpox were unleashed as a weapon. How might the virus be released? Probably in aerosol form or even in the old-fashioned wa­y: by sending an infected individual directly into the target area.

The method for unleashing a biological weapon doesn't have to be flashy, however.

Anthrax

Most cases of anthrax are cutaneous, transmitted through skin contact with the spores. The most deadly form is inhalation anthrax, when the spores travel to the lungs and then the immune cells carry them to the lymph nodes. Here, the spores multiply and release toxins that result in such symptoms as fever, respiratory problems, fatigue, muscle aches, enlarged lymph nodes, nausea, vomiting, diarrhea and black ulcers. Inhalation anthrax carries the highest mortality rate of the three (100 percent, 75 percent with medical treatment), and unfortunately, that was the form contracted by all five casualties from the 2001 anthrax letters [source: NPR].

The disease isn't easy to catch under normal situations, and it can't be transmitted from person to person. Still, health workers, veterinarians and military personnel normally undergo vaccinations. The rest of us, however, remain at risk if someone were bent on another anthrax attack.

Along with the lack of widespread vaccination -- a common theme among our scary bioweapon nominees -- longevity is another point in anthrax's favor. Many harmful biological agents can only survive a short while under certain conditions. But hardy B. anthracis can sit on the shelf for 40 years or more and still pose a lethal threat.