sentences:  Sprites have been held responsible for otherwise unexplained accidents involving high altitude vehicular operations above thunderstorms.Although jets are considered to be a type of upper-atmospheric lightning, it has been found that they are components of tropospheric lightning and a type of cloud-to-air discharge that initiates within a thunderstorm and travel upwards.In contrast, other types of TLEs are not electrically connected with tropospheric lightning—despite being triggered by it.