The satellites used by meteorologists fall into two categories. Polar-orbiting satellites pass around the earth from pole to pole at a height of about 870 km. It takes approximately 1 hour 42 minutes for the satellite to complete its orbit, by which time the earth has rotated by about 25 degrees. Consequently, each pass provides information about a different strip of the atmosphere. The polar-orbiting satellites provide pictures of clouds, and information about the temperature through the atmosphere.
Geostationary satellites remain over the equator, stationary with respect to the earth.
This is achieved by having the satellite in orbit at a height of about 36,000 km. At this height it takes exactly 24 hours to complete one orbit, so it always views the same part of the globe. Meteosat, the European geostationary satellite, like its US, Japanese and Indian counterparts, gives time sequences of cloud images. From these, wind speeds and directions can be calculated by examining consecutive frames. Hurricane and storm tracks can also be monitored using this imagery.