10 EXTREMELY RARE WEATHER EVENTS

10 Extremely Rare Weather Events
By Mark Hill, Toptenz, 24 November 2014.

It’s easy to get sick of having the same weather day after day, but drastic changes can really shake people up. These are some of the rarest natural phenomena out there - some are beautiful, others are deadly, and they all leave people in awe.

10. Multi-coloured Snow

On a freezing cold morning in 2010, citizens of Stavropol, Russia woke up to multi-coloured snow lining their streets. People were stunned when they saw light-purple and brown snow piled up. Others who heard the story may have thought it was a hoax, but scientists investigating the matter confirmed that there was a snowfall consisting of a multitude of colours.

It wasn’t toxic, but the experts warned that it wouldn’t be wise to ingest any of the snow as it was most likely contaminated by dust all the way from Africa. The dust reached dizzying heights in the upper atmosphere where it mingled in with normal snow clouds. This interaction is what caused the beautifully coloured snow to fall. That wasn’t the first time it happened - in 1912, black snow fell over Alaska and Canada. The black colour was thanks to volcanic ash and rocks that also mingled with snow clouds.

9. Derecho

In 2012, a massive and violent storm system made up of several thunderstorms and strong winds left a trail of destruction across the Midwest and mid-Atlantic. This terrifying type of storm is called a derecho, and in this case the storm was upgraded to a “super derecho” due to its severity.

The main cause of the super-storm was the intense heat experienced over the area combined with a ripple in the jet stream. The state of Virginia experienced a massive power outage - cables snapped like twigs, trucks tumbled right over like they were made of cardboard and 13 people were killed.

Derechos are very rare across the mid-Atlantic, only occurring every four years or so. Another extremely destructive derecho occurred in the United States in 2009. The storm system travelled 1000 miles in one day, leaving several dead and even more injured. A terrifying 45 tornadoes hit the ground during this storm.

8. Thundersnow

Residents of the east coast of the United States were experiencing an ordinary snow storm in 2011 when they suddenly witnessed flashes of lightning and streaks of thunder intermingled with the snow. Thundersnow was happening right in front of their eyes.

Thundersnow mimics the inner workings of a normal thunderstorm by forming through the upward movement of humid air. It’s the combination of lower humid air and higher cooler air that cause lightning and thunderstorms. This is exactly why thundersnow is so rare, seeing as how warm lower ground temperatures aren’t usually present while it’s snowing.

Weather experts noted that the occurrence of thundersnow likely means more heavy snowfalls. Researchers have found that there’s an over 80 percent chance that a minimum of six-inch deep snow will fall within a radius of seventy miles of the lighting flash taking place during a snowstorm.

7. Colourful Solar Storm

We all know the northern lights, which usually appear as blue and green swirls in the sky. However, sometimes solar storms are so intense that they cause a kaleidoscope of colours to appear and can also be seen in regions where people have never witnessed them before. In 2012, one of these intense solar storms created a particularly beautiful aurora over Crater Lake in Oregon. It was believed by scientists that two clouds of glowing particles were flung toward Earth by sunspots bigger than our planet. The intensity of the auroras caused them to be seen as far as Maryland and Wisconsin, and they also put on a beautiful show in Canada on their way down from the Arctic.

6. Twin Tornadoes

Tornadoes occur every year around the world, but twin tornadoes only occur every ten to twenty years. When they do show up, they cause massive destruction. The town of Pilger in Nebraska has first-hand experience of the sheer damage these tornadoes can inflict in a matter of minutes. The twin tornado phenomenon hit the town in 2014, resulting in the death of a child and the injury of nineteen others.

There’s some disagreement on just how twin tornadoes are formed. Some experts believe that the occlusion process is conducive to the forming of these twisters. Occlusion takes place when a single tornado is wrapped with cold damp air. When this “wrapped” tornado starts to weaken it can cause a second tornado to spawn off itself. This usually happens when there’s a lot of energy present in the original storm.

Others argue that multiple-vortex storm systems or even separate super cells are to blame for twin tornadoes. Whichever it may be, all experts agree that twin tornadoes are deadly and a place of shelter is imperative in the event of this phenomenon.

5. Gustnado

Gustnado is the term used for a brief tornado that’s completely separate from the main thunderstorm that usually spawns regular tornadoes. In 2012 a severe thunderstorm spawned a gustnado at the edge of a high-speed wind in southeast Wisconsin. This rare phenomenon stunned the local fire department, who rushed to the aid of people caught up in the storm.

A gustnado isn’t as strong as a tornado and is formed when a downpour of rain draws cold air down with it from the inside of a storm. The cold air that’s forced downward with the rain hits the ground hard and then spouts a gust of wind, which in turn becomes a gustnado. A severe gustnado usually forms when a lot of the cold gusts formed on the ground mix with the hot air there. Gustnadoes only last for a few minutes, but they’re still capable of inflicting some serious damage on their surroundings.

4. Inversion Clouds

Just after Thanksgiving in 2013, visitors at the Grand Canyon noticed something weird - the canyon was rapidly filling up with a thick fog. Tourists were left in awe when the fog rolled into the park and eventually formed what looked like a waterfall of clouds. This weather anomaly is known as an inversion.

An inversion is caused by cold air remaining near the ground and warmer air moving over it. The inversion at the Grand Canyon started when a storm moved through just before the holiday, causing the ground to freeze. When the warmer air then moved through afterward, the beautiful inversion phenomenon took place. Rangers at the park confirmed that much smaller inversions occur fairly often, but the larger ones that fill up the entire Canyon only happen every ten years or so. This one lasted the whole day, with the fog only dissipating when it started getting dark.

3. Solar Tsunami

2013 was a good year for rare weather events. In the middle of the year, two satellites caught something unusual happening on the surface of the sun. A tsunami was rolling on its surface as a reaction to an ejection of matter into space.

The injection and subsequent solar tsunami gave scientists a greater understanding of the dynamics of a tsunami and how they occur on Earth. The Japanese satellite Hindoe and the Solar Dynamics Observatory (SDO) are instrumental in researching events that happen on the sun, and they both study its ultraviolet light to establish the exact conditions on the surface.

Hindoe was also thought to have gathered enough data for experts to finally figure out why the corona of the sun is thousands of degrees hotter than its surface. It was during all of this research that scientists became aware of shock waves following the matter ejection. This incident was very similar to the movement of a tsunami on Earth after an earthquake has taken place. The shock waves are very rare, making a solar tsunami a rare phenomenon as well.

2. Super Refraction

Also in 2013, people living in northern Ohio woke up one morning and were stunned to find that they could see all the way to the Canadian shoreline. This is not at all possible under normal circumstances because of the way the Earth is curved. However, locals were able to see all the way to Canada because of a rare natural phenomenon known as super refraction, where rays of light are bent downward toward the surface of Earth. The rays are bent this way because of changes in air density. During this light-bending, far-off objects can be seen that are usually hidden from view because they’re reflected in the rays of light. The light from the sun had bent so far down over Lake Erie that the refraction made the Canadian shoreline visible from more than fifty miles away.

1. Atmospheric Blocking

Atmospheric blocking is quite possibly the rarest weather event on Earth, which is good because it’s also one of the most dangerous. It happens when a high pressure system gets stuck and can’t move from one place to another. Depending on the type of system it can either lead to flooding or extremely hot and dry conditions.

An example of atmospheric blocking is the 2003 European heat wave that killed 70,000 people. The high-pressure system that became stuck in this instance was very powerful and blocked any relieving fronts from passing. In 2010, 15,000 Russians were killed by a heat wave caused by another blocking incident. And in 2004 atmospheric blocking in Alaska caused such hot temperatures that glaciers started melting and large forest fires started up in the area. It’s not always doom and gloom, though - in another 2004 blocking, positive effects were noted in Missouri as temperatures remained pleasant and eventually produced fantastic crops.

Top image: A solar tsunami seen by NASA's Solar Terrestrial Relations Observatory (STEREO) spacecraft from orthogonal points of view. Credit: NASA.

[Source: Toptenz. Edited, Top image added.]