How Weather Satellites Work — Eyes in the Sky

Two Types of Weather Satellites

Geostationary Satellites

Orbit at 35,786 km above the equator
Match Earth's rotation, so they hover over the same spot
Provide continuous monitoring of weather over one region
Update images every 5-15 minutes
Examples: GOES (US), Himawari (Japan), Meteosat (Europe)

Polar-Orbiting Satellites

Orbit at 850 km altitude, circling pole-to-pole
Cover the entire globe every 12 hours (overlapping orbits)
Pass over any point twice daily
Closer orbit means higher-resolution images
Examples: NOAA satellites, Suomi NPP, MetOp

What They Measure

Instrument	What It Detects
Visible imager	Cloud cover, fog, smoke (daytime only)
Infrared sensor	Cloud top temperatures, night-time storms
Water vapour channel	Moisture in the atmosphere
Microwave sounder	Temperature and humidity profiles through clouds
Lightning mapper	Lightning frequency and location

How Satellites Improve Forecasts

Satellites provide the initial conditions that weather models need to make predictions. Without satellite data, forecast accuracy would drop by about 2 days — today's 5-day forecast would only be as good as a 3-day forecast.

Satellite Images Explained

Visible: Shows clouds as white against dark ground — like a black-and-white photo from space
Infrared: Shows temperature — cold (high) clouds are bright, warm ground is dark. Works day and night.
Water vapour: Shows moisture in the middle atmosphere — useful for tracking jet stream patterns and dry air intrusion

See satellite-informed forecasts on Weather Tomorrow.