Context:

  • Unseasonal and sudden heavy rainfall, accompanied by thunderstorms, hailstorms and lightning strikes, have so far claimed 27 lives in Gujarat on November 26.

What explains the unseasonal rainfall in November?

  • The India Meteorological Department (IMD) has attributed the lightning flashes to three weather systems – cyclonic circulation over the Northeast Arabian Sea and adjoining Saurashtra and Kutch, Western Disturbances, and Easterly trough.
  • Western disturbances are storms that originate over the Mediterranean Sea region and may bring rainfall to northwestern India in the winter.
  • Whereas, easterly winds flow from the east in the equatorial region throughout the year.

Why the lightning?

  • There are two reasons for lightning strikes.
  • Whenever there is an interaction between any system and Western Disturbance it always leads to lightning.
  • Also, the first spell of activity after a long dry period leads to convective activity that results in lightning.

About lightening:

  • Lightning is a natural phenomenon formed by electrostatic discharges through the atmosphere between two electrically charged regions, either both in the atmosphere or with one in the atmosphere and on the ground, temporarily neutralizing these in a near-instantaneous release of an average of one gigajoule of energy.
  • This discharge may produce a wide range of electromagnetic radiation, from heat created by the rapid movement of electrons, to brilliant flashes of visible light in the form of black-body radiation.
  • Lightning causes thunder, a sound from the shock wave which develops as gases in the vicinity of the discharge experience a sudden increase in pressure.
  • Lightning occurs commonly during thunderstorms as well as other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions.
Syllabus: Prelims; Geography