  During thunderstorms, the atmospheric electric field can increase above
hundreds of kV/m, causing an acceleration in the charged particles of secondary
cosmic rays. Such an acceleration causes avalanche processes in the atmosphere,
enhancing/reducing the particle flux at ground level depending on the
strength/polarity of the electric field. We present the design and
implementation of a self-triggered and fast-recording lightning monitoring
system used to study the transient electric field atmospheric effect on the
secondary particle flux above cosmic ray observatories. The acquisition device
records lightning electric field at 10 $\mu$s resolution (during 1.2 s per
event), covering a detection range up to 200 km ($I_{peak} >$ 100 kA)
