S: http://www.prep4agthreats.org/Natural-Disasters/thunderstorms (last access: 25 June 2015); http://www.ready.gov/thunderstorms-lightning (last access: 25 June 2015).
N: 1. also thunder-storm, 1560s, from thunder (mid-13c., from Old English þunor “thunder, thunderclap; the god Thor,” from Proto-Germanic *thunraz, from PIE (s)tene- “to resound, thunder” + storm (Old English storm “violent disturbance of the atmosphere, tempest; onrush, attack, tumult; disturbance,” from Proto-Germanic sturmaz storm, from PIE stur-mo-, from root *(s)twer- “to turn, whirl”).
2. Sudden electrical discharges manifested by a flash of light (lightning) and a sharp or rumbling sound (thunder).
3. Thunderstorms are associated with convective clouds (Cumulonimbus) and are, more often, accompanied by precipitation in the form of rainshowers or hail, or occasionally snow, snow pellets, or ice pellets.
4. Cultural Interrelation: We can mention the novel Ordinary Thunderstorms (2009) by William Boyd.
S: 1. OED – http://www.etymonline.com/index.php?search=Thunderstorm (last access: 25 June 2015). 2 & 3. METEOTERM/IMV/OMM (last access: 25 June 2015). 4. http://www.washingtonpost.com/wp-dyn/content/article/2010/02/16/AR2010021605221.html (last access: 2 July 2015).