Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or one on the ground, temporarily equalize themselves, causing instantaneous release of as much as one gigajoule of energy. This discharge may produce a wide range of electromagnetic radiation, from very hot plasma 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 waves, which develop as gases in the vicinity of the discharge experience a sudden increase in pressure. Lightning occurs commonly during thunderstorms and other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions.
Lightning frequency on earth is approximately 44 (± 5) times per second, or nearly 1.4 billion flashes per year, and the average duration is 0.2 seconds made up from a number of much shorter flashes (strokes) of around 60 to 70 microseconds.
Many factors affect the frequency, distribution, strength and physical properties of a typical lightning flash in a particular region. These include ground elevation, latitude, prevailing wind currents, relative humidity, and proximity to warm and cold bodies of water. To a certain degree, the proportions of intra-cloud, cloud-to-cloud, and cloud-to-ground lightning may also vary by season in middle latitudes.
Objects struck by lightning experience heat, and magnetic forces of great magnitude. The heat created by lightning currents traveling through a tree might vaporize its sap, resulting in a steam explosion that might burst the trunk. When lightning travels through sandy soil, the soil surrounding the plasma channel might melt, forming tubular structures called fulgurites.
Buildings or tall structures hit by lightning might be damaged as the lightning seeks unimpeded paths to ground. Aircrafts are highly susceptible to being struck by lightening due to their metallic fuselages, but lightning strikes are generally not dangerous to them as the fuselage acts as a Faraday cage due to the conductive properties of aluminum alloy.
Even though 90% people survive lightning strike, persons struck by lightning might suffer severe injury due to internal organ, and nervous system damage.
Lightning is responsible for large number of weather-related deaths. It is however common for people to greatly underestimate the probability of being involved in a lightning strike. Actual statistics however does not support this assertion. Lightning strikes the ground more than a billion times every year. According to researchers the chances of an individual being killed, or injured during a given year is 1:240000. Assuming an average life span of 80 years, a person’s odds over their lifetime becomes 1:3000. Assuming that an average person has 10 family members, and others with whom she is close, then the chances are 1:300 that a lightning strike would closely affect her during the lifetime.
It is therefore important to be aware of lightening, and invest time, and resources on effective protection from the same.