Problems. Electrical phenomena in nature

Clouds rub against one another and against layers of air and become strongly charged. A powerful electric spark jumps between two oppositely charged clouds, or between a cloud and the ground: this is lightning. The air along its path is heated and expands in an instant, and thunder rumbles. Light travels 300 000 km in 1 s, sound in air only about 340 m, so we see the flash first and hear the thunder later; multiplying the delay in seconds by 340 m gives the distance to the flash. When the charge of a cloud passes to the ground in a moment, it is called a lightning strike; it hits tall conducting objects first: towers, trees, poles. A lightning rod is a pointed conductor joined by a thick wire to a metal stake buried in the ground; it leads the charge to the ground without harming the building. During a thunderstorm stay indoors or in a closed building; do not shelter under a lone tree or a haystack, and do not go to high places.