Colour enhanced infrared satellite images are measurements of temperature thus only the differences in temperatures are visible. In an IR image darker is warmer and lighter is colder. Low clouds tend to be warmer than higher clouds. Water vapor images are useful for pointing out regions of moist and dry air. This provides information about the swirling troposphere's wind patterns and jet streams.
Darker colours indicate drier air while moisture in the air is seen as white.
The European Geostationary satellite currently transmitting to us is Meteosat 7. This satellite orbits the Earth at approximately 36,000 kilometres above the Earths surface and appears to be stationary over a specific point. The Meteosat satellite is at 0 longitude above the equator and sees the same view of the globe as this. From the point of working with satellite data, data from Geostationary satellites is superior in that it can be received according to a timetable where a new image is transmitted every 4 minutes. Every half an hour the globe is scanned and the data is split in to smaller blocks and sent down according to a dissemination schedule.