The 2015 December solstice — Winter in the Northern Hemisphere, and Summer in the Southern Hemisphere — occurred at 0448 UTC on 22nd day of the month. Several hours prior to the solstice, the daylight/darkness “terminator” (tilted at 23.5º due to the inclination of the Earth’s axis) could be seen moving from east to west across North America on GOES-13 (GOES-East) Visible (0.63 µm, 1-km resolution) images (above).

The terminator was also seen on GOES-15 (GOES-West) Visible (0.63 µm, 1-km resolution) images (below), albeit a few hours later. Note that areas of northern Canada and northern Alaska remain dark during the entire day; for example, at Barrow (the northernmost city in Alaska), their polar night — the period with no sunlight — lasts about 65 days, from mid-November to late January.

For a global perspective, we can examine Himawari-8  true-color Red/Green/Blue (RGB) images (below), which cover the period before, during, and after the 0448 UTC solstice time — the animation pauses briefly on the 0450 UTC image, nearest the time of the solstice (also available as longer MP4 movie file). One feature that stands out quite prominently (due to a favorable forward scattering angle) is the dense haze covering much of the Indian subcontinent and the adjacent offshore waters. These images were generated using an update (version 2) of the Simple Hybrid Contrast Stretch (SHCS) method, which uses the AHI 0.86 µm band to “boost” the green of the 0.51 µm band, and stretches each of the 3 color components (R/G/B) on both the dark and light ends. Similar full-disk true-color images will be available every 5 minutes from the ABI instrument on GOES-R.

The Himawari-8 data was provided by JMA and acquired via NOAA/NESDIS/STAR; the SSEC Data Center served the AHI data via McIDAS ADDE, and McIDAS-X was used for the processing.