WeatherQuestions.com - Concise and interesting answers to the most-often asked questions about the weather, arranged in alphabetical order. National Severe Storms Laboratory - The National Severe Storms Laboratory is one of NOAA's internationally known Environmental Research Laboratories, leading the way in investigations of all aspects of severe weather. Headquartered in Norman OK with staff in Colorado, Nevada, Washington, Utah, and Wisconsin. Top Weather, Water, and Climate Events of the Twentieth Century - Background information on the top weather events around the world. Compiled by NOAA. Bew - Incredible Weather - Image galleries of weather phenomena in Canada as well as tools for chasing tornadoes on the internet. Site in both English and French. About.com - Arizona Monsoon Thunderstorms - Get details and safety tips about Arizona's monsoon season, which begins in July and lasts several weeks. Australian Weather Photographs - Pictures and descriptions of Australian hailstorms, tornadoes and severe weather. Contrail Science - Investigation of the science and history behind "chemtrails", showing that they are really contrails. Includes many historical photos and accounts. National Geographic - Forces of Nature - Learn more about earthquakes, volcanoes, tornadoes, and hurricanes through maps, photos, and 3D animations.