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Weather

Watching weather from space

The weather is the state of the atmosphere at a particular place and time, whether it is raining, dry, windy or snowing.

The complex patterns of the Earth’s weather are basically due to the uneven heating of the planet by the Sun. This causes temperature differences which set the atmosphere in motion as weather systems carry heat from the lower latitudes towards higher latitudes.

High and low pressure areas, winds, clouds and rain or snow are all caused directly or indirectly by this uneven heating of the Earth by the Sun.

Weather Forecasts

The weather has a big impact on our lives, so reliable weather forecasts are essential, especially when there is a chance of extreme weather such as storms, heat waves or tropical cyclones.

Weather forecasts are also crucial for the day-to-day operations of business and industry: pilots, farmers, fishermen and sailors, and the retail, energy, tourism and construction industries all rely on accurate weather forecasts to be able to operate.

Today’s weather forecasts rely on the might of powerful supercomputers, which process hundreds of thousands of observations of current weather conditions through mathematical models of the oceans and atmosphere, to forecast future weather.


The Earth from 36 000 km as seen by EUMETSAT’s Meteosat-10 satellite
Click here to see this view in real-time

This is known as numerical weather prediction and is the basis of modern weather forecasting.

A weather forecast is only as good as the data it is based on and so accurate knowledge of the current state of the atmosphere and Earth's surface is critical for numerical weather prediction. 

Meteorologists therefore rely on data from a global network of weather stations, radar, radiosondes, ocean monitoring buoys  etc. And to get the big picture of what is going on in the atmosphere they rely on weather satellites.

Watching the weather from space

Europe’s weather satellites are operated by EUMETSAT, and there are two main types: the geostationary Meteosat and the polar-orbiting Metop satellites.

The new supercomputer in use with the German Weather Service (Deutscher Wetterdienst) has the capacity of more than 30,000 PCs

Meteosat

The Meteosat satellites are in geostationary orbit 36 000 km above the Earth. As they travel at the same speed as the Earth, they stay over the same spot above the Equator and are able to deliver the full view from their vantage point every fifteen minutes, or a smaller view of Europe every five minutes.

These satellites are particularly useful for detecting the development of weather such as storms or fog and predicting their behaviour over the next few hours. Data is also used for longer range weather forecasting and climate monitoring.

The main instrument on-board the Meteosat Second Generation satellites is the SEVIRI instrument which observes rapidly changing weather patterns and provides detailed images 24 hours a day.

The SEVIRI instrument’s 12 spectral channels are able to provide information on storms, clouds, winds, fog, rain, snow, incoming solar radiation, volcanic ash, dust, land and sea surface temperature and even fires.

 

This movie shows the development of thunderstorms over Europe on 18-19 June 2013, as seen by the Meteosat-10 satellite in orbit 36,000 km above the Earth. Imagery from Meteosat allows continuous monitoring of all stages of storm development.

Meteosat Second Generation

The current Meteosat system, built around Meteosat Second Generation (MSG) satellites and their main instrument SEVIRI, is capable of scanning a full disc image of the Earth in 15 minutes or Europe within 5 minutes, when used in Rapid Scanning Service (RSS) mode. EUMETSAT simultaneously exploits two Meteosat Second Generation satellites to deliver both the full disc imagery and the rapid scan service over Europe.

Fog From Space

Meteosat imagery allows 24-hour monitoring of the distribution and behaviour of fog. It is used, in combination with other techniques, to help detect and monitor fog formation and forecast when it is likely to dissolve. This information is particularly important around airports, major road networks, and shipping routes and ports.

Metop

The Metop satellites circle the globe, roughly from pole-to-pole. Because they are closer to the Earth – at an altitude of 817 km – they can provide a much closer, more detailed global view of the atmosphere, ocean and land.

Each Metop satellite carries eight main instruments for taking measurements of the atmosphere, including temperature and humidity profiles, cloud properties, and greenhouse and trace gases such as ozone, nitrogen dioxide, and sulphur dioxide.

Metop instruments also observe the ocean and continental surfaces, providing measurements of wind at the ocean surface, ice, snow and soil moisture.

 

Data from Metop’s instruments, such as temperature and humidity and winds are used for weather forecasts up to 10 days ahead. The satellites also play a key role in climate and environmental monitoring.

Follow Metop Live

A year of weather across the globe – from space

This visualisation was created using imagery from the geostationary satellites of EUMETSAT, NOAA and the JMA. It shows an entire year of weather across the globe during 2015 as seen by satellites 36 000 km above the Earth. The commentary is by Mark Higgins, Training Officer at EUMETSAT.

 

Back in time - the first weather satellite

The world’s first weather satellite, TIROS-1, was launched on April 1, 1960, from Cape Canaveral, Florida. TIROS (Television Infrared Observation Satellite) was a polar-orbiting satellite that carried two cameras and two video recorders.
 
It was the first satellite that gave scientists a view of the Earth from space and heralded a new era of satellite meteorology.

Useful Links

WMO - Weather and climate  education website

Met Office Factsheets - A series of factsheets providing an insight into various aspects of the weather

Météo-France - The Météo-France education website (in French)

MetLink web siteResources for teaching weather and climate in schools

Key Facts

  • The complex patterns of the Earth’s weather are due to the uneven heating of the planet by the Sun.
  • Weather forecasts are crucial to protect lives and property and for the day-to-day operations of business and industry.
  • A weather forecast is only as good as the data it is based on, so meteorologists rely on a global network of weather stations, radar, radiosondes, ocean monitoring buoys etc. and weather satellites.
  • Europe’s weather satellites are operated by EUMETSAT, and there are two main types: the geostationary Meteosat and the polar-orbiting Metop satellites.
  • The main role of the Meteosat satellites is to help detect and forecast rapidly developing high impact weather, such as thunderstorms or fog, up to six hours ahead.
  • Metop satellites, which are closer to the Earth, provide a more detailed global view and their data is used for weather forecasting up to 10 days ahead and climate and environmental monitoring

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