Red sky in the morning; shepherd's warning.
There is a little scientific validity behind this phrase which I'm sure you all learned as a child although some may know it with "sailor" rather than "shepherd". I won't bore you with the science, but last night on the summit of Mauna Kea we witnessed one of the most spectacular sunsets I've seen in a while, especially once the sun had actually set but unfortunately, in astronomy, a red sky at night is usually a warning. Last night it really should have been two warnings: the night would be bad (although it did clear up a bit later) and watch out you stupid astronomer, try not to trip and twist your knee!
Like us, the NASA IRTF opens the dome early to help cool the dome and although it's hard to observe at this time of day it helps with image quality at the start of the night; the local turbulence caused by warm air rising from the telescope optics, its structure and the dome itself is reduced. The IRTF actually cools the dome during the day so the effect is reduced, but it always helps to try and equalise temperatures as early as possible.
The sky was stunning in the south-west...
...but even more beautiful in the west. Here Subaru and one of the Kecks are silhouetted against the sky and the brilliant red clouds at a level, unfortunately, above the summit. We would fight these clouds all night. It was also about this time I managed to trip on something I didn't see (my eyesight still isn't back to what it should be after a problem a few weeks ago) and although I didn't make a spectacle of myself by sprawling all over the lava rocks, I think I twisted my knee. There was no pain at the time but a couple of hours later I could hardly move my left knee and I've been hobbling all day today! Duh!