A weather satellite is a satellite which is used by meteorologists to gather information about the weather.
Weather satellites give meteorologists a view of weather patterns over a very large area. This enables meteorologists to track large weather patterns and make more accurate predictions of future weather behavior.
In addition to visual monitoring, weather satellites may also use thermal imaging, X-ray sensors, high-energy proton detectors, alpha detectors, and energetic particle sensors.
Weather satellites in geostationary orbits provide views of the same portion of the earths surface 24 hours a day. Weather satellites in polar orbits move across the surface of the earth and are able to provide a view of the entire planet over the course of a 12 hour orbit.
NASA makes weather satellite images from their Geostationary Operational Environmental Satellite (GOES) systems available on the web at the Global Hydrology and Climate Center.