("TRANSIENT LUMINOUS EVENTS")
Above the clouds thunderstorms, gigantic jets of light
rise up to the ionosphere
sometimes. These flashes of light are called T.L.E. They are
hardly visible to the naked eye. But some astronauts from
Space Station were able to see, when they were just over
a violent thunderstorm and at the right time as these events
last less than a second.
here to see a video of sprites and blue jets ESA 750ko.
Credit : Danish National Space Center
They are bright flashes that occur in the
above cumulonimbus is
20 to 96 km altitude over a width of 15 km. This is when
the electric field is strong enough and the air tenuous
enough, then the electrons will accelerate to the speed
required to transport their kinetic energy in the molecules
they encounter, what excites and releases this energy in
form of light called sprites. They occur only above active
thunderstorms and they are mostly associated with positive
lightnings so when the lightnings go down towards the ground.
They are mainly red and they usually don't last more than
a few milliseconds. The first images of a sprite were obtained
by chance in 1989. To see them you must be able to see above
the thunderstorm and a view on a dark background stellar.
Because of their low brightness, the sprites can't be seen
in the presence of light, as found in cities. The best distance
to see is to be 200-300.km
from the thunderstorm. At this distance the sprites are
a vertical angular distance of 10-20°.
Halo sprites precede sprites and propagate
downward from about 85 to 70 km altitude and last about
a millisecond. These halos are thought to be produced by
the same physical process that produces sprites, but for
which the ionization is too weak to cross the threshold
required for streamer formation.
Farfadets or Sprites
here to see this animation of
filmed Sprites, gif format : 1 MB
Just after the sprites it can appear the
elves, and their duration is more ephemeral, less than a
thousandth of a second. They occur above the clouds positive
or negative polarity during a lightning. The origin of the
elves are powerful lightnings that emit electromagnetic
pulses propagating very quickly from lightning. They can
be spread on 400 km in diameter. When the upper part of
this "sphere" reached an altitude of approximately
75 to 100.km, the electrons
will be accelerated by an electric field conveyed by these
impulses. The gas molecules will be excited and affected
by the electrons such that they will release the surplus
energy into light in the form of a ring. This occurs so
rapidly that this ring will be seen as a flattened disc.
They were discovered in 1994.
These optical phenomena were observed for
the first time in 1994. They are conical jets of blue light
propagating from the top of the electrically active core
regions of thunderstorms to the upper atmosphere at a speed
of about 74,56 mps (120 km/s) and don't exceed 40 km altitude
with a lifetime of a couple of tenths of a second. But they
aren't associated with cloud-to-ground lightning. They are
also brighter than sprites. Blue jets occur much less frequently
here to see the animation
of the Blue Jet in format gif : 850ko
gigantic jets are by far the rarest of
TLE that have so far been discovered. The first confirmed
gigantic jet was reported in 2001, after American researchers
saw a blue jet reaching 70 km above the clouds at the Arecibo
Observatory in Puerto Rico.These electrical discharges can
take several forms, such as sprites (orange-red flashes)
and blue jets, which appear as blue cones.
Trolls, also recently observed, resemble
blue jets, but are red and seem to occur after tendrils
of vigorous sprites extend downward toward the cloud tops.
of radio waves, X-rays and gamma
Gamma and X ray bursts of short duration
(about 1 millisecond) were detected by the Compton satellite
who observed gamma rays from space. These rays occur above
the thunderstorms regions and their sources are assumed
to be at altitudes of more than 30 km. When sprites are
produced by a relativistic electron avalanche triggered
by cosmic radiation, electron beam may interact with air
molecules and produce X-rays and secondary gamma. Sprites
require an energy of about 20 electronvolts. But gamma rays
in demand over a million electronvolts.
Violent lightnings emit radio waves into the
Van Allen belts which is situated in the magnetosphere
which is an extension of the Earth's magnetic field
that reaches the outer layers of the atmosphere. Energetic
electrons traveling near the speed of light between
the two ring-shaped zones, separated by a space known
as the region of the slot of the Van Allen Belt, consisting
of turbulence. This space is where the aurora borealis
creates what could be a safer place for the orbits
During solar flares emitted particles decompose
instantly and flow around the area of the slot of
the Van Allen belt.
The Van Allen belt upper and
lower and between the region
of the slot of the Van Allen belt