Wednesday 3 June 2009

A little convection

One small and lonely cloud remains near Mauna Kea's summit at sunset. It's quite usual to have plenty of clouds surrounding the summit in the late afternoon and those less experienced visitors might think this is no place to do astronomy. Almost invariably, however, when the sun starts to set and the temperatures drop, these clouds disappear as the convection driving their formation dies away. Sometimes the odd cloud hangs about, perhaps there's a small hotspot on the mountain, but this little fellow will soon be no longer. In the distance the summit of Hualalai Volcano protrudes through the inversion layer.

No green flash again, perhaps I'm colour blind? No matter, the sky exhibits some extraordinary colours after the sun has set, but for the astronomers at the summit there's little time to admire the view now. Their workday has just begun.

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