The rocks that cause meteors orbit the sun in streams, along the path of the space body that they originated from (usually a comet or a shattered asteroid).
When Earth passes through this debris trail in space, a meteor shower is visible in the sky. An exceptionally intense shower is called a meteor storm. One meteor shower with the potential to become a storm is 2014’s Camelopardalids (kah-MEL-oh-PAR-dal-ids).
On the night of May 23-24, 2014, Earth passes through the debris trail of Comet 209P/LINEAR. Observers in North America will get a good view of the meteors.
The intensity of the meteor shower depends on how active the comet was centuries ago. Currently, the comet produces few meteors, but fragments that broke off the comet 100 to 300 years ago will be strewn along the path where the Earth crosses.
Source SPACE.com: All about our solar system, outer space and exploration