"The lower air is full of positive electricity just as the surface of the earth is charged with negative electricity. As you know, boys, rain is formed by a lot of little drops of moisture combining to form one large drop, which, when it is heavy enough, falls to the ground. Now the surface of every drop of moisture is charged with electricity. When these drops come together to make one big drop, the surface of the big drop is proportionately much smaller than the combined surfaces of all the small drops. There isn't room enough on the surface of the big drop to hold all the electricity that existed on the surface of the larger number of smaller drops and, therefore, a great deal of electricity is set free.
Eiffel Tower Struck by Lightning.
Unusual example of attraction of electric discharge. This great structure in Paris is struck in almost every thunderstorm.
Lightning Flash Striking Building.
Single disruptive discharge of great intensity, at Greensboro, N.C. This non-branched form is rare.
Courtesy of Gen. Electric Co., Schenectady, N. Y.