Satellite image of the month

Showcasing some of the Met Office's satellite imagery from around the world showing weather in action, new views of the world and extra commentary on how we collect and create the images from our Satellite Applications team.

 

February 2017: Green, swirling "eye".

20 February 2017 - Lake Maracaibo, Venezuela - duckweed outbreak

Looking like a great, green swirling eye from space, this is in fact an outbreak of duckweed on Venezuela’s Lake Maracaibo. The lake is brackish, connected to the Caribbean Sea by a narrow channel.  During heavy rains, mixing of the fresh rain water with the salty lake water can cause the duckweed, already present in the lake, to rapidly increase in amount giving the vibrant green colour. The influx of sea water through the channel causes currents in the lake giving the swirling appearance.

The Moderate-resolution Imaging Spectroradiometer (MODIS) on board NASA's Aqua satellite provides useful information on changes to the Earth's surface as well as information on atmospheric dynamics, water vapour, cloud and aerosols. This is a true-colour image, combining information from three visible channels on the instrument to give an image as it would appear to the human eye.

January 2017: Two images, one day apart, from NASA's Terra Satellite.

25 January 2017 - Rare snowfall over the Sahara Desert

December 2016 saw what was reported as the first snow in the Sahara desert for 37 years. The snowfall continued in January, completely covering some dunes and creating waist high drifts. This remarkable occurrence can be seen in this high resolution image, created using data from NASA’s Terra satellite, from over 700km above.

26 January 2017 - Chile wildfires

Drought conditions and high temperatures in Chile's central Maule region in January led to the rapid spread of wildfires, causing a state of emergency to be declared as the fires caused widespread destruction and deaths. The image above shows the extent of the fires and smoke on 26 January.

NASA's Terra satellite contains a Moderate-resolution Imaging Spectroradiometer (MODIS). This instrument measures incoming radiation from the Earth and it's atmosphere as it orbits 710 km above the surface of the Earth. Each orbit takes 99 minutes to complete. If we combine the measurements from three visible wavelengths, corresponding to red light, green light and blue light, we can create a 'true colour' image which looks like a photograph.