Inside the big dark thunderclouds on a stormy day are millions of tiny droplets of ice. These collide with each other all the time, creating 3.(a)… electric charge with a small amount of electricity. In no time, they could get filled up with charges.

Electric charges 4.(to be) … neither positive nor negative. When negative charges from the bottom of the cold and positive charges of the ground meat, a flash 5.(see)… . This flash is the path of the electrical charges. All this happens in a fraction of a second.

Lightning heats the air around 6.(pronoun)…  to temperatures up to 30,000 degrees Celsius. This is more than five times hotter than the surface of the Sun. When air 7.(heat)…  so quickly, it 8.(expand) …and contracts violently, much like a 9.(balloon) bursting. The explosion 10.(hear) as thunder. Lightning and thunder happen at the same time, but why do we always see lightning first and hear thunder later? This is because light travels almost a million times faster than sound.