5 September 2010 The Green Flash

Speed 13 knots (kts) Course 249° Location Southern Canada Basin, 73.25° N, 149.98° W Depth 3773 meters

SPECIAL FEATURE DISCUSSION:

(see previous journal for the questions.)

The answer to yesterday's riddle (What grows like grass on our railings at night but gets mowed down by Arctic sunlight? ) is frost. We've had some spectacular overnight growths of hoarfrost crystals, sometimes well over an inch long. It grows best on windward side railings and lines when the night has been foggy and breezy.

TODAY'S JOURNAL:

I enjoyed Star Wars (episode 4) last night, my last hangar movie of the trip last night. It brought to mind the long line I waited in to see the movie when it first came out in 1977. But even better was the sunset underway as we came out of the hangar. By then we'd broken out of the ice pack, with only occasional drifting floes here and there as visual reminders of where we were. We've progressed far enough south and far enough on the calendar to start having sunsets again, but most of the recent ones had been fog-obscured. Last night, though, the Sun was slanting in through clear skies. Up here the Sun takes a long time to set because of its low angle approaching the horizon. It prolonged some nice moments as the bright disc seemed to be rolling along the edge of the Earth. The Sun dipped below the horizon, leaving an orange glow, but then a delightful phenomenon occurred. Right over the spot where the sun had disappeared a bright green light winked on at the horizon. It glowed like a green traffic light for a few seconds, long enough for me gawk and take a few pictures, before it winked back out. This was the legendary 'green flash' another optical phenomenon produced by atmospheric refraction. While green flashes can occur nearly anywhere on Earth, they usually only last a second or so. But in the Arctic & Antarctic, the low angle of the sunset or sunrise can prolong the effect. I'd estimate the one I saw last night lasted between 5 and 7 seconds. Though I'd heard of the green flash, this was the first time I'd seen one in my life. My simple understanding of this phenomenon is that the red, yellow, and orange end of the spectrum is refracted the most while the purple and blue end are scattered the most by our atmosphere. When conditions are right with a layer of different density air near the Earth's surface, those ends get winnowed out (the red end refracted away and the blue end scattered away), leaving the middle of the spectrum (the green part) visible to the observer as it refracts over the horizon.

We're blasting along now through open water towards Barrow, but the ocean is still littered with ice here & there. A bit of a sea is developing but the ship's ride is comfortable as we are going nearly with the swell. Overnight there were some very loud bangs and vigorous shaking as we nailed ice floes in the dark going 15 knots or so. Today we have to get totally packed and cleaned up. This evening we weigh ourselves and all of our luggage in preparation for helicopter flights off the Healy to Barrow. We also have to get checked out of our cabins, settle our accounts at the ship's store, etc. Helo opps begin at 07:00 tomorrow so I've got to pretty much be set to get up and go early. I'll do my best to check in tomorrow but if I don't it is because the travel day got to be too busy for me.

That's all for now! Best- Bill