Light Pillars: Amazing Natural Phenomenon
September 10, 2009
Photo credit: National Geographic
From a distance, it looks like someone spared no expense to put on a spectacular, colorful light show that can be seen from miles away. But these strange columns of light that often confound onlookers are actually caused by the combined forces of light and falling ice crystals.
Photo credit: Walter Tape
Usually seen only in polar regions, light pillars – as this phenomenon is called – result when natural or artificial light bounces off ice crystals as they waft to the ground. When the light source is close to the ground, the pillars appear above the floating crystals. When the light is coming from the sun or moon, the pillars appear beneath the crystals.
Photo credit: National Geographic
The height and brightness of light pillars depends upon the shape of the ice crystals. Crystals with plate or column shapes produce the most stunning effects. Ice crystals that cause light pillars can be found in ice clouds, ice fogs, blowing snow and what is known as diamond dust – ground-level clouds made up of tiny ice crystals.
Photo credit: ArborSci.com
While light pillars formed by sunlight may only extend a few degrees, in artificial light, they can extend 90 degrees or more depending on your vantage point.
Learn more about the science of light pillars at The Weather Doctor.
Link [National Geographic]
Fire Tornadoes Make Forest Fires Even More Deadly
August 18, 2009
Photo credit: Josh Lane
Forest fires are already frightening and deadly enough on their own, but when the conditions are right, something hellish happens: fire whirls. Fires sometimes spawn their own winds as the flames consume oxygen, creating tornadoes filed with fire and noxious gases.
From Discover Magazine:
All these wonders start with the plume that is formed as the heated air rises from the fire in a column. Usually a strong prevailing wind quashes such a plume before it can grow. But when the fire is especially hot and the wind is weak, the plume can prevail. “Wind is the most critical weather component for fires,” says Margaret Gross, a meteorologist for the National Weather Service in Riverside, California. “It determines more than anything else how fast a fire will spread. But when the power of the fire is greater than the wind, these large plumes can rise high into the atmosphere. Those are the fires that usually generate weather.”
Photo credit: Boston.com
Fire whirls develop in a similar manner to dust devils, growing from a heat source close to the ground. When there’s a little instability in the atmosphere, with warm, rising currents, the whirl’shitting a cliff or some other obstacle.
Fire whirls can reach 300 to 400 feet in height, and 20 to 50 feet in width. As they blow over the surface at five to seven miles per hour, they can ignite new fires in unburned areas.
Photo credit: Wikimedia Commons
In 1923, the Great Kanto earthquake in Japan spawned a massive fire whirl that killed 38,000 people in just fifteen minutes. Three years later, numerous fire whirls developed after lightning struck an oil storage facility near San Luis Obispo, California, killing two and producing significant structural damage.
Link [Wikipedia] + [Discover Magazine]
Rare ‘Smiling Rainbow’ Seen Over Sussex, England
August 13, 2009
Whoever heard of an upside-down rainbow? People in Sussex, England glimpsed an extremely rare phenomenon when “freak atmospheric conditions” created a ribbon of light in the sky shaped like a smile. But what they saw technically wasn’t even a rainbow at all.
From The Daily Mail:
While normal rainbows are formed when light penetrates raindrops and emerges on the other side without changing direction, the smile is formed when sunlight shines through millions of tiny ice crystals in cirrus and cirrus stratus clouds.
Because the crystals are flat and hexagonal, they invert the light and create an upside-down curve called a circumzenithal arc.
The phenomenon relies on the sun being low in the sky, normally less than 32 degrees from the horizon.
The arcs can appear at any time of the year, hovering in the sky only fleetingly because clouds tend to move quickly near the zenith.
The Sussex ‘upside-down rainbow’ was in the sky for about five minutes, onlookers say, and then suddenly it was gone.
Another strange phenomenon in the sky was captured by scientists earlier this year – the “eye of God’ or Helix Nebula, which is actually a dying star that resembles a human eye with a blue pupil, white of the eye and a pink lid created by layers of gas
Link [The Daily Mail]
That’s not a UFO, it’s a Lenticular Cloud!
June 29, 2009
What’s that round, dense-looking object hovering in the sky? It wouldn’t be too hard for UFO believers to assume, particularly at twilight when they’re backlit, that these strange formations are actually alien aircraft. But, what you’re looking at is a natural phenomenon. Lenticular clouds form at high altitudes, aligned to the wind direction, and often seem to stay in the same place while other clouds move around them.
Lenticular clouds are particularly common over mountains, where strong wind flow pushes moist air upward, causing it to condense. They often look like discs, stacks of pancakes, funnels, or mushrooms. Sometimes, the air is forced in a pattern that resembles waves in the sea.
While they appear stationary, that’s actually not the case. The flow of moist air continually resupplies the cloud even as water evaporates, keeping the same shape until the wind or weather changes.
While power pilots try to avoid flying near lenticular clouds because of the turbulence of the rotor systems, sailplane pilots actively seek them out because they enable gliders to soar extremely high and far.
Check out this time lapse video of lenticular clouds forming over Mount Rainier:
Image via icestories.exploratorium.edu
So next time you see what you think might be a UFO, look a little closer. It might just be a mundane – yet spectacular – lenticular cloud formation.
Link [Wikipedia]
The Bizarre Natural Phenomenon of Ball Lightning – Photos and Video
January 29, 2009
Image via Xenophilia
No, that’s not a UFO you just saw travel across the horizon. That bizarre orb of glowing light is called ‘ball lightning’, and despite many reports of sightings over hundreds of years, scientists still know very little about this strange and unusual natural phenomenon.
They can’t tell us what causes it, or even exactly what it is. They can’t explain why people report being able to get startlingly close to these orbs, which reportedly range in size from tennis balls to beach balls, and seeing them roll on the ground.
Image via Xenophilia
National Geographic has a first-hand account from Graham K. Hubler, a physicist at the U.S. Naval Research Laboratory in Washington DC:
“It drifted along a few feet above the ground,” Hubler recalled, “but when it came inside [the pavilion] it dropped down to the ground and skittered along the floor.”
“It made lots of gyrations or oscillations and a hissing sound like boiling water. When it went out the other side [of the pavilion], it climbed back up [several feet off the ground].”
Hubler says the ball behaved as if it had a charge and was following electric field lines along the Earth.
“I remember telling people what I had seen, and they thought I was crazy, so I stopped talking about it,” he said.
There are around 10,000 written accounts spanning many countries, all with similar observations. The sightings generally accompany thunderstorms, but scientists aren’t sure whether ball lightning is related to conventional lightning. Ball lightning floats near the ground, sometimes bouncing off the ground or other surfaces, doesn’t react to wind and defies the laws of gravity. An average ball lightning glows with the brightness of a 100-watt bulb, and some people have even reported seeing it melt glass windows.
Images via Ern Mainka Photography
We’ve included some photos here that purport to be of ball lightning, but it’s difficult to say whether that is really what has been captured. The one below shows what researchers believe might be ball lightning created in a laboratory.
Image via Max-Planck-Institut für Plasmaphysik
These videos may have captured ball lightning in action:
From National Geographic:
The record suggests that ball lightning is not inherently deadly, but there are reports of people being killed by contact—most notably the pioneering electricity researcher Georg Richmann, who died in 1753.
Richmann is believed to have been electrocuted by ball lightning as he conducted a lightning-rod experiment in St. Petersburg, Russia.
The phenomenon lasts only a short time, perhaps ten seconds, before either fading away or violently dissipating with a small explosion.
Theories include plasma clouds composed of charged particles that recombine into atoms and glow with light, as well as small particles holding together in a ball by electrical charges emitting chemical energy through oxidation. Researchers are trying to reproduce the conditions that seem to cause ball lightning in a laboratory setting to research the phenomenon further.
Bizarre, shocking and strange – it just goes to show that there is still so much mystery in this world, so many things we can’t explain or understand.
Link [National Geographic]
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