Lightning is one of the most fascinating and mysterious weather phenomena, and although storms do occur regularly, we still do our best to understand the phenomena generated in the sky.
There is one type of lightning that is very strange and very rare, and in fact, we didn’t even have concrete evidence of its existence until 1990, when researchers identified its “rocket-like” motion in a video clip from NASA’s space shuttle the previous year.
Later, they were dubbed “blue planes,” and the streaks were now recognized as bright flashes of light lasting a few hundred thousandths of a second, as lightning flowed upward from the clouds into the stratosphere.
We cannot easily see this phenomenon under a veil of clouds – but that does not mean that scientists cannot observe it from above. It orbited about 400 kilometers (250 miles) over the planet around the International Space Station, and for some time, instruments on board watched these mysterious flashes of inverted lightning.
Now that it was equipped in 2018, the European Space Station observatory, equipped with optical sensors, photometers, and gamma and X-ray detectors, recorded five blue flashes from the top of a storm cloud, one of which ended with a blue line high in the stratosphere.
These rare glimpses provide some valuable insights into the beginning of mysterious conjugations, according to a team of researchers led by physicist Thorsten Newbert of the Technical University of Denmark.
The blue jets are thought to start when the crest of a positively charged cloud meets a layer of negative charge at the boundary of the cloud and the layer of air above it. This is believed to produce an electrical breakdown that forms a leader – an invisible conductive channel for ionizing air through which lightning travels.
However, our understanding of the blue pilot is very limited. This is where the data analyzed by Newbert and his team fills the gaps.
On February 26, 2019, the Atmospheric and Space Interactions Observatory (ASIM) recorded five blue flashes, each about 10 microsecond in length, at the top of a storm cloud, not far from the island of Nauru in the Pacific Ocean.
One of these flashes produced a puff of blue, reaching the stratopause – the interface between the stratosphere and the ionosphere, at an altitude of about 50 to 55 km (about 30 to 34 miles).
(Gemini Observatory / AURA / Wikimedia Commons)
In addition, the observatory recorded meteorological phenomena called ELVES (short for light emission and very low frequency disturbances due to electromagnetic pulse sources). These are expanding rings of optical and ultraviolet emission in the ionosphere that appear above the storm clouds, lasting only a millisecond or so, as shown in the animation.
It is believed to be generated by an electromagnetic pulse at the bottom of the ionosphere, resulting from the discharge of lightning.
The Commander’s red emissions, however, were very dull and limited. This indicates that the leader himself is very short, compared to the fully developed lightning commanders between the Earth and the clouds, the research team said.
This also indicates that the flashes and the blue plane itself are a type of discharge stream: twisting branching sparks that emit from high-voltage sources, such as Tesla coils, upon a chain reaction of ionizing air molecules.
The researchers believe the flashes resemble narrow bipolar events. These are the high-energy radio-frequency discharges that occur inside clouds during thunderstorms, which are known to cause lightning within the cloud.
The team said that the blue flashes at the tops of the cloud are likely the visual equivalent of this phenomenon, and could develop into blue jets.
And since narrow bipolar events are so common, this may mean that blue flashes are more common than we thought. Knowing more about how common they are could give us a better understanding of storms and lightning, not to mention our atmosphere and all the complex interactions in it.
The team’s research has been published in a journal Nature.