Upon a comet, which is like a type of star that is seen like an arrow across the sky from place to place, whose light stretches like a staff, and upon shaking of the earth, and upon lightning, and upon thunder, and upon winds that blow angrily: on each of these one says, "Blessed are you, God our Lord, king of the world, creator of the original (first) creations." And if you'd like, say, "Blessed are you, God our Lord, king of the world, whose strength and might fill the world."
כל זמן שלא נתפזרו העבים נפטר בברכה אחת נתפזרו בין ברק לברק ובין רעם לרעם צריך לחזור ולברך:
If one was sitting in a restroom and heard the sound of thunder or saw lighting: if it is possible to leave within toch kedei dibbur [the amount of time it takes to greet one's teacher, about two seconds], they should leave, otherwise not.