Discover The Inner Life of Lightning from Station

Have u ever witnessed the ferocious and elegant light show that appears in the night sky? Yeah, the gigantic branch of electric discharge that startles us with the terrific sound. But, what human eyes can see is only a small portion of the lightning. The most powerful activity occurs high above the surface in the Earth’s upper atmosphere.

‌The breaking of the notion that lightning is confined to clouds has been facilitated by using instruments on the International Space Station. The instruments are part of the Atmosphere Space Interactions Monitor(ASIM), an ESA Earth observation facility on the outside of the space station. It recorded high energy Terrestrial Gamma Rays (TGF) and Transient luminous events( TLE), emanating from upper atmospheric lighting phenomenon. The findings are reported in a paper recently published in the journal ‘Science’.

Lightning is a rapid discharge of electricity that temporarily equalize opposite charges within a cloud or between a cloud and the ground. Charging of the cloud is powered by convection and further collision leads to lighter particles carrying positive charges upwards while heavier particles carrying negative charges downwards. The atmosphere acts as an insulator between the electric field until the charges overcome this field. Then the lighting leader, a long spark forms between regions of the cloud or between the cloud and ground in a rapid manner making it hard for humans to see. When the leader connects to the ground, we see a bright flash of high current, the lightning strike.

‌Measurements suggest that gamma-ray flash is generated by the electric fields with the lighting leader. When a thunderstorm generates very high energy electrons that burst out into the upper atmosphere, X rays and gamma rays lasting for only milliseconds are measured by the ASIM.

TGFs occur at altitudes well above the normal lightning and storm clouds, so measuring them is a challenge. As the lowest platform in space, much lower than satellites, ASIM’s instrument also point directly downward from the space station, making it possible to catch as many photons in a lightning flash as possible.

Another space station instrument, NASA’s Lightning Imaging Sensor (LIS) intended to study the characteristics of lightning helped in understanding the relationship between lightning and severe weather. Integrating the data from LIS and ASIM will be beneficial in understanding how thunderstorm affects the Earth’s atmosphere, better weather and climate forecasts.

Author

Gokul M Nair

See author's posts