How do weather satellites work? 

While supercomputers, radar and ground-based observations all play crucial roles, it is satellites that have truly transformed our ability to monitor the atmosphere on a global scale.  

But how do they work? In this article, we’ll take a look at how these satellites observe the atmosphere, the technology behind them, and why they have become essential tools in modern weather forecasting. 

From the first images to global coverage 

Before satellites existed, forecasters relied on surface reports, sparse upper-air observations and the limited view offered by ships and aircraft. The launch of the first dedicated weather satellites in the 1960s marked a profound shift in our ability to observe, analyse and predict the weather.  

The modern era of satellite meteorology began on 1 April 1960, when NASA launched TIROS1, the world’s first weather satellite equipped with television cameras. For the first time, meteorologists could see cloud patterns from space, gaining insights that had never been possible with ground-based observations alone. Although TIROS1 operated for just 78 days, it proved that satellites could observe the atmosphere effectively, paving the way for an entire fleet of more sophisticated missions.  

Throughout the 1960s and 1970s, the TIROS series expanded, followed by ESSA and Nimbus satellites, which introduced infrared imaging. This innovation meant that forecasters could “see” weather systems at night by measuring cloudtop temperatures, an essential capability that transformed storm tracking and monitoring. For the first time, hurricanes could be watched continuously from orbit, helping forecasters better understand their development and behaviour.  

Europe also entered the scene with the Meteosat programme, beginning in 1977. Since then, successive generations have added increasingly sophisticated sensors. Launches of the latest generation of Meteosat satellites have taken place over the past few years, and we are now beginning to realise the benefits as their instruments enter operational service. These new satellites provide exceptionally high-resolution imagery and carry a range of advanced sensors, including lightning detectors, instruments that measure three-dimensional profiles of temperature and humidity, and sensors capable of detecting tiny airborne particles that influence both health and air quality. 

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How satellites observe the atmosphere? 

Today’s weather satellites carry a suite of specialist instruments designed to measure different aspects of the Earth system. These include: 

• Imagers (visible/infrared) – deliver multispectral, high-frequency observations of reflected and emitted radiation, supporting detailed analysis of cloud structures, convection, and surface features. 

• Sounders (infrared/microwave) – retrieve vertical profiles of temperature, humidity, and atmospheric gases, supporting numerical weather prediction, identifying atmospheric stability and convection potential, and other key applications in atmospheric analysis.  

• Specialised sensors – including lightning mappers, scatterometers (winds), atmospheric-composition sensors (aerosols/trace gases), and GNSS Radio Occultation (GNSSRO) instruments for precise atmospheric profiling. 

Together, these sensors track storms, monitor sea-surface temperatures, measure wind speeds and detect volcanic ash, lightning and even smoke from wildfires. The data is then transmitted to ground stations around the world, where it is processed by powerful computers for numerous applications. Some of the data is used in numerical weather prediction models. These models underpin the forecasts and severe weather warnings issued by meteorological agencies, including the Met Office.  

In essence, satellites act as our “eyes in the sky,” giving meteorologists continuous, rea-ltime insight into atmospheric changes. 

Polar orbiters and geostationary sentinels 

Weather satellites generally fall into two categories: polar-orbiting and geostationary, each offering different advantages.  

Polar-orbiting satellites travel from pole to pole, scanning the entire Earth as the planet rotates beneath them. They provide high-resolution imagery and detailed temperature and humidity profiles, making them invaluable for climate studies and long-range forecasting. Because they fly relatively close to Earth, they capture finer detail, but they cannot continuously observe the same region. 

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Geostationary satellites, on the other hand, orbit at the same speed that the Earth rotates, allowing them to remain fixed over one location. This positioning is essential for monitoring rapidly developing weather systems such as thunderstorms, tropical cyclones and frontal systems. The launch of the first geostationary weather satellite, SMS1, in 1974 marked another major leap forward. Europe’s Meteosat satellites and the US GOES series remain central to real-time weather observation today.  

By combining the strengths of both types, meteorologists gain a complete picture: global coverage from polar orbiters and continuous regional monitoring from geostationary platforms. 

Engineering marvels built for space 

Behind every satellite is remarkable engineering. Modern instruments must survive launch vibrations, extreme temperatures and the vacuum of space. One example is the Advanced Microwave Sounding Unit – B (AMSU-B), an instrument procured and tested by the Met Office in the 1990s before being first flown on a NOAA satellite in 1998, and then on two subsequent missions. These instruments measured microwave emissions related to atmospheric water vapour, data essential for understanding moisture distribution in the atmosphere and improving forecasts. Due to the high quality of the instrument and testing, the three AMSU-B instruments all surpassed their design lifetime of five years. AMSU-B data was in use until 2014, providing vital input to weather forecasting models across the globe. 

AMSU-B paved the way for subsequent instrument programmes including the Microwave Sounder MWS launched on EUMETSAT's Metop Second Generation (Metop-SG) just this year. Today, missions are built for even greater durability, with advanced thermal protection and more efficient electronics.  

Supporting forecasting, safety and climate science 

Modern weather satellites are far more than cloud-spotting tools. They provide critical data for: 

• Numerical weather prediction, significantly improving forecast accuracy. 

• Disaster response, such as tracking tropical cyclones or monitoring volcanic ash clouds. 

• Air-quality assessments, by observing pollutants and smoke plumes. 

• Climate monitoring, including long-term changes in temperature, humidity and atmospheric composition. 

These satellites support meteorologists, climatologists and emergency services worldwide. Their data helps save lives, protect property and inform decisions in aviation, agriculture and public safety.  

The future of weather satellites is set to be even more innovative. New generations will likely be smaller, more agile and equipped with faster-updating sensors. Artificial intelligence will play an increasing role in analysing satellite data, helping meteorologists extract useful insights more quickly and accurately. Despite these technological advances, the goal remains the same: to understand the atmosphere better and to provide reliable, timely information that keeps people safe.  

From the early images captured by TIROS1 over 60 years ago to the sophisticated systems orbiting Earth today, weather satellites have reshaped meteorology. Next time you check the forecast, spare a thought for the silent sentinels high above us, watching, measuring and helping us understand our everchanging planet. 

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