1. Gravity Wave
Unusual image of a wave cloud forming off Amsterdam Island in the Indian Ocean, December 2005.
The undulating pattern of a gravity wave must seem a bizarre sight, especially if you’re more used to seeing waves of the water, not in the sky.
Seldom seen gravity waves are caused when air is displaced in the vertical plain, usually as a result of updrafts coming off the mountains or during thunderstorms.
A wave pattern will only be generated when the updraft air is forced into a stable air pocket. The upward momentum of the draft triggers into the air pocket causes changes in the atmosphere, altering the fluid dynamics. Nature then tries to restore the fluid changes within the atmosphere, which present in a visible oscillating pattern within the cloud.
Here’s some time lapse footage of a gravity wave.
2. Katabatic Winds
Derived from the Greek word ‘katabatikos’, which means going downhill, the katabatic winds carry high density air from high elevations down slopes under the force of gravity, sometimes reaching hurricane speeds.
Katabatic winds are found in many parts of the world. Their name changes depending on where they are located and how they’re formed but the some of the better known are the Bora in the Adriatic, the Mistral in the Mediterranean and the Santa Ana in California.
In Antarctica the winds are at their strongest and most fierce. Air directly above the chilly surface is cooled by radiation, and since air becomes denser at lower temperatures it flows downwards naturally, close to the ground. The effects are enhanced in the Antarctic due to much colder temperatures, resulting in rapid drops in the surrounding air temperature that then cause the flow of air to speed up. The winds in Antarctica have been measured at over 200 mph, making them some of the strongest winds measured on the planet at ground level, even greater than some of the most treacherous tornadoes.
Here’s a video of katabatic winds in action.
Going purely by the name, Supercell sounds as cool as it is. It is the name given to a continuously rotating updraft deep within a severe thunderstorm (a mesocyclone) and looks downright scary.
Supercells are usually isolated storms, which can last for hours, and sometimes can split in two, with one storm going to the left of the wind and one to the right. They can spout huge amounts of hail, rain and wind and are often responsible for tornados, though they can also occur without tornados. Supercells are often carriers of giant hailstones and although they can occur anywhere in the world they’re most frequent in the Great Plains of the US.
4. Giant Hailstones
Of all the crazy weather phenomena that blast the planet, a giant hailstorm would be the most likely to cause direct personal injury, judging by the size of the hailstones in these images anyway. Just imagine being pelted from a great height with hundreds of hard golf balls and the only thing you have for protection is a flimsy umbrella!
Cross-section of a giant hailstone.
Giant hailstones occur when compacted snow is blown upwards as well as downwards, further compacting the snow, producing even bigger hailstones. Obviously hailstones this heavy can’t hang around in the clouds for too long so they soon precipitate out and fall to the ground.
The largest hailstones, which are formed under very unusual atmospheric conditions, are called megacryometeors and have been known to reach up to 25lbs (10 kg).
5. Non-Aqueous Rain
Although a well-known phenomenon, non-aqueous rain is seldom reported or documented but when it is, a media frenzy usually ensues, although with cries of the world ending.
A shower of frogs in Wiltshire, England made the headlines in 1939, as did a coal storm in 1983 when a number of yachtsmen in Dorset regaled stories of lumps of coal falling from the sky.
Yoro man cooking fish that fell from the sky.
But one of the most bizarre events is a recurring shower of fish that falls between the months of May and July in the Honduran Departamento de Yoro. Now called the Festival de la Lluvia de Peces – Rain of Fish Festival, the people of Yoro celebrate the free fish offerings every year.
It is generally thought that the animals (or minerals) are sucked up by powerful updrafts during a storm and then spat out with heavy rains, though meteorologists are still investigating the phenomena.
6. Snow Donuts
These strange looking snow donuts were snapped in Ajax, Ontario.
The spherical snow rings known as snow donuts, or snow rollers, only happen when conditions are perfect. The temperature must be around freezing, the snow easily packable and there must be strong winds. A bit of a hill always helps too.
When the snow falls, especially if there are imperfections or tufts on the ground, the winds blow the snow around. Where there are imperfections, little snowballs start to form naturally. They grow and gather as gusting winds blow them along the ground. Small holes then develop in the centre where the first snow gathered as it’s less compacted and is easily blown away by the force of the wind, turning the snowballs into snow donuts large enough to make even Homer Simpson happy.
7. Red Sprites and Blue Jets
Appearing as cone bursts, glows or bright discharges, blue jets and red sprites occur only in the upper atmosphere, and are therefore very faint and often not visible to the naked eye.
These natural phenomena have a lifespan of only a few hundred milliseconds at most so capturing them on camera is very difficult. However, the Danish National Space Centre have placed cameras on mountain tops to study how elves and sprites are created, how often they occur and what it means for the environment.
Red Sprites are found above large thunderstorms and are often associated with larger cloud-to-ground lightning flashed. They are at their most luminous high in the atmosphere and last only a few thousandths of a second.
Blue jets are discharged around thunderstorms and extend for many miles up into the atmosphere. It’s thought they provide a mechanism for energy transfer between thunderclouds and the lower ionosphere.
8. Fire Whirls
Fire whirls often occur during bush fires. Vertical rotating columns of fire form when the air currents and temperature are just right, creating a tornado-like effect.