• Blue jets seem to appear when the positively-charged upper region of a cloud interacts with the negatively charged boundary between the cloud and the air above, according to the report.
• The blue jet appears as a result of this "electric breakdown," where the opposing charges swap places in the cloud and briefly equalize, releasing static electricity.
• The properties of blue jets and the altitude to which they extend above clouds "are not well characterized," the authors noted, so this study adds to our understanding of the dramatic phenomenon. 
  

What are blue jets?

• Blue jets are initiated as “normal” lightning discharges.
• The positive end network fills the negative charge region and after that the negative end fills the positive charge region.
• After that, the positive end exits the cloud and starts propagating upward.
• Earlier, it was believed that blue jets are directly related to lightning flashes but it is the result of the hails.
• The blue jets are brighter than sprites and are blue in colour.
• The blue colour of the jets is the result of blue and near-ultraviolet emission lines from neutral and ionized molecular nitrogen.
• The blue jets were recorded on October 21, 1989 for the first time.