A weather satellite (or meteorological satellite) is a spacecraft that observes Earth's atmosphere, surface, and oceans from orbit. Weather satellites revolutionised meteorology when the first one — TIROS-1 — was launched in 1960. Today, a constellation of operational satellites provides continuous, global coverage that is essential for weather forecasting, tropical cyclone tracking, climate monitoring, and disaster response.
Two types of orbit are used. Geostationary satellites (GEO) orbit at 35,786 km above the equator, matching Earth's rotation — they remain fixed over one location, imaging the same hemisphere every 5–15 minutes. Europe's Meteosat Third Generation (MTG), the US GOES series, and Japan's Himawari provide this persistent view. Polar-orbiting satellites (LEO) fly at 800–850 km in sun-synchronous orbits, passing over each point twice daily and providing higher-resolution global data. Europe's MetOp and the US JPSS/NOAA series carry instruments that profile temperature, humidity, and composition through the atmosphere.
Modern weather satellites carry sophisticated instruments: visible and infrared imagers (detecting cloud type, height, and thickness), microwave sounders (profiling temperature and moisture through clouds), lightning mappers, and ocean surface wind scatterometers. The data are transmitted to national meteorological services worldwide via the WMO's Global Telecommunication System. Satellite imagery is arguably the most impactful tool in meteorology: it enabled the detection and tracking of tropical cyclones in ocean areas with no other observations, saving countless lives through earlier warnings.