Can the weather actually smile?
Posted on 04 Jan 2023
This may seem a rather bizarre question. The ability for the weather to change our moods is well known. Some individuals prefer warm and sunny weather, and there are those individuals known as pluviophiles, who can find comfort, peace and joy during rainy days.Weather watchers around the world can find the sheer variability of our weather patterns fascinating.
As with people, our weather is complex, varied and can show countless different characteristics.
One weather mood is known as the Circumzenithal arc. This looks like an upside-down rainbow - a multi-colored smiling face, hovering above the ground, with its spectrum of colors pointing upwards. Although these smiling rainbows are actually quite common, they are not always seen as they are often obscured from the ground by clouds.
Even though these wonderful phenomena seem to be similar to rainbows, they are actually formed in different ways. The traditional rainbow is formed by light bending and being separated as it passes through rain droplets. The Circumzenithal arc is created as light is refracted through hexagonal ice crystals, held in cirrus clouds, in a very specific way.
The clouds that contain the ice crystals need to be at a very specific angle to the sun’s rays to convex the light. The sun needs to be between five and thirty-two degrees above the horizon. The height, depth and position of the clouds also need to be just right for the weather to smile. In addition, the air needs to be relatively still to enable the ice particles to orientate themselves the same way, this means that there needs to be a lack of turbulence, and very little updraft or downdraft.
Sprites, Trolls, Gnomes and Elves
These may sound as if they come from the imagination of J.R.R.Tolkien, but are in fact weather phenomena that are surrounded in myth and mystery. Some were once considered figments of imagination, and given fairy-tale names such as red sprites, blue jets, elves, trolls and gnomes. These are bright flashes of light that happen high above thunderstorm clouds. Sightings were first documented, and dismissed as fables as far back as 1886. But it was not until 1989 that researchers from the University of Minnesota actually captured these elusive events on film.
Unlike lightning, that travels from the clouds down to earth, these enigmatic entities flow upwards. Scientifically known as Transient Luminous Events or TLEs, the light is caused by large scale electrical discharges from cumulonimbus clouds upwards, to the electrically charged ionosphere. They are often triggered by positively charged lightning flowing from the underlying thunder cloud and the ground. They can sour up to 60 miles high, and last for just a fraction of a second.
The red sprites, which are the most frequent of TLEs, are most commonly seen above the American Midwest, as well as in clusters above the troposphere. As their name suggests, they appear to be bright flashes of red light.
In contrast, Blue Jets can only be seen from an aircraft, they are a dim blue color, and appear to be similar to smoke, rising up from a hailstorm.
Elves - or “Emissions of Light and Very low frequency from EMP Sources”, are dim discs of light that appear about 60 miles high in our atmosphere.
Trolls - “Transient Red Optical Luminous Lineament” are the red spots of light that follow a red sprite, and can be seen just above the tops of the clouds.
Gnomes - Are the smallest and quickest of all TLEs, and are small, white flashes of light that appear above the anvil of a thunderstorm.
These mysterious TLEs do not form where our normal weather exists in the troposphere ( 4 to 12 miles high), but rather far higher in the world’s mesosphere, about 50miles above the surface.
Let OpenWeather help
These other worldly phenomena need to be seen by night, away from light pollution, as well as bright moonlight. There also needs to be a strong thunderstorm, approximately 200 miles away to prevent the clouds obstructing the view. Patience is also needed, as sprites only occur on average once every 200 lightning strikes.
The OpenWeather Global Weather Alerts API is the perfect tool to create your own custom weather alerts. Our Daily Forecast 16 Days can help you plan your weather watching giving 16 days of accurate forecast data.
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