24 September 2012

Can You Tell The Date From Space? Yes!

Posted by Dan Satterfield

Meteosat 9 SEVERI Image from the European weather satellite. Taken at 18 GMT Saturday 22 Sept. The equinox was 14:49 GMT Saturday.

Notice the Shadow in this image taken Saturday. It is due North/South,and this happens only on the equinoxes. In other words it must be either late September or late March. You can actually tell it is late September instead of March, by looking at the incredible amount of sea ice around Antarctica. It is late winter there, and Antarctica nearly doubles in size (if you count the ice) during the winter.

The reason the clouds seem blue in this image is due to the different wavelengths of light sensed by the SEVERI sensor on the Meteosat. There are enough channels for an ALMOST true colour image. The blue tinge in the very high clouds is explained well by CIMMS here.