USA Today
Usa Today: Rising Air Creates Spring, Summer Ice
This article gives you basic information on hail. There are links at the bottom of the page to how hail forms, how updrafts breed hail and thunderstorms.
NASA
Nasa: Image Science Center: Ask the Space Scientist Earth
Site from NASA contains a collection of 91 questions pertaining to the Earth's atmosphere, magnetic field, ionosphere, rotation and origin of life.