They don't. No idea where you got this from, but this couldn't be farther from the truth, and something I have NEVER seen in all my years of helping raising cattle, AND seeing the many thunderstorms that roll through! It is true that cattle do die during thunderstorms, but only if they were hit by lightning, not just because some thunderstorm, big or small, rolled though.
Lightning can strike up to 30 miles from a thunderstorm, though such instances are rare.
Sheltering under a tree during a thunderstorm is not safe because trees are a prominent target for lightning strikes. Lightning tends to strike taller objects, and trees can conduct the electricity from a lightning strike to the ground, putting anyone near them at risk of electrocution. It is safer to find shelter in a sturdy building or a fully enclosed vehicle during a thunderstorm.
Alexander Stepanovich Popov invented lighting detection in 1894. It detects the likelihood that lightning will strike at a point in time during a thunderstorm.
Lightning can strike up to 30 miles from the parent storm cell, though such cases are rare.
Within 10 miles of the parent thunderstorm
A thunder storm is one in which a large amount of thunder is heard. Thunder is caused by lightning; it would be more correct to say that a thunderstorm only occurs with lightning strikes.
No, it is not possible for sheet lightning to strike a person. Sheet lightning refers to the illumination of a widespread area of the sky due to a distant thunderstorm. It does not actually involve a physical discharge of lightning that can strike objects or people.
A thunderstorm does not strike anything, it is "lightening" that does that.
Lightning can strike at any time of day or night. Worldwide there are about 100 lightning strikes every second.
During thunderstorms, avoid places where lightning may strike. Also avoid places that conduct electricity, such as metal objects and bodies of water.
Because the angle of a strike of Lightning can bring massive wind storms that cause a tornado.
Electricity travels fairly easily though water. Therefore, if lightning strike in or near a pool, any one in it has a good chance of being electrocuted.