Friday, May 1, 2009
Thursday, April 23, 2009
Monday, April 20, 2009
Dusk...to dawn...to dusk
The picture above is labeled 'Dusk' by the photographer, but have you ever thought about all the official terms we have for the different times of day? I'm completely enthralled with the colors of the sky, regardless of the terms we use, but just for my future reference, if nothing else, here are some of those terms. Most information below was gleaned from a NOAA site.
[Astronomical dawn]
This is the time at which the sun is 18 degrees below the horizon in the morning. Astronomical dawn is that point in time at which the sun starts lightening the sky. Prior to this time, the sky is completely dark.
[Nautical dawn]
This is the time at which the sun is 12 degrees below the horizon in the morning. Nautical dawn is defined as that time at which there is just enough sunlight for objects to be distinguishable.
[Dawn or civil dawn]
This is the time at which the sun is 6 degrees below the horizon in the morning. Civil dawn is defined as that time at which there is enough light for objects to be distinguishable and that outdoor activities can commence.
[Twilight]
The time between civil dawn and sunrise.
[Sunrise]
The time at which the first part of the sun appears above the horizon in the morning.
[Solar noon]
This is the time at which the sun is the highest in the sky. This time varies through the year due to the change in speed of the earth's orbit around the sun.
[Sunset]
The time the last part of the sun disappears below the horizon in the evening.
[Twilight]
The time between sunset and civil dusk.
[Dusk or civil dusk]
This is the time at which the sun is 6 degrees below the horizon in the evening. At this time objects are distinguishable but there is no longer enough light to perform any outdoor activities.
[Nautical dusk]
This is the time at which the sun is 12 degrees below the horizon in the evening. At this time, objects are no longer distinguishable.
[Astronomical dusk]
This is the time at which the sun is 18 degrees below the horizon in the evening. At this time the sun no longer illuminates the sky.
Thursday, April 16, 2009
Monday, April 13, 2009
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Saturday, March 28, 2009
It's Otherworldly Out There
This afternoon was beautiful in Anchorage. The sun was out; it was warm; the skies were clear...well, mostly anyway. Just a little bit of grayish-looking cloud here and there. But those occasional gray clouds were sort of like nagging feelings that you shrug away. They probably weren't ash clouds, I thought. And then, What does an ash cloud look like anyway?
I had other things on my mind, so I drove on, thinking about maybe going cross-country skiing in the park a little later. The darn volcano has been ruining my skiing plans for days now. It was time to go ahead and just go for a quick few laps around the stadium. The skis are brand new, for heaven's sake. I've only used them once. Good plan. After my errand. Driving on...
I was at a friend's house a little later, looking at (coincidentally) some amazing pictures of Redoubt on The Anchorage Daily News' website (referenced above). The dogs wanted out, so I turned around, opened the sliding glass door and the first thing that caught my eye was the deck. Earlier it had been clear. Now it was dusted with snow...dirty snow...didn't look quite right. And I noticed an odd odor--maybe like sulphur or soot or something--not sure what. As my eyes lifted, I noticed the rest of the snow beyond the deck--the snow that was formerly white--was dusted with ash. Oh no! "Ash!" I called out, like I'd just sighted a plague of locusts.
My wife was, as usual, quicker to act, as she quickly retrieved the dogs. I then quickly shut the door after the dogs were in and set about doing what I do best: I stewed. We weren't home and I wanted to be home. That meant I had to drive the truck, but when there's ash about, you really don't want to drive your vehicles any more than you absolutely have to. So now my sweet truck was going to be covered in ash--that's bad enough--but I was going to have to drive the thing--that's another really bad thing to do with the ash. So in the end, we just hunkered down while waiting for one of two things to happen: either I would run out of patience and just go on home or the skies would dramatically clear and I would go home then.
As it happened, the former happened first (as former things are wont to do). The sun was setting and I was running out of patience, so I headed on home, driving slowly so as not to ingest any more ash than necessary through the air intake. I set the air conditioning system to recirculate the air, put on a dusty old air mask (time for a new one!) from my wood shop (smelled like poplar) and repeatedly reminded myself not to use the wipers lest I scratch the glass with the ash.
Driving home the skies looked like something out of a movie. It was surreal. I wish I had a fraction of Sue Grafton's gift for metaphor so I could paint a better picture. If you've ever seen the skies when massive terrible thunderstorms are all about, when you know tornadoes are about to plunge out of the sky any moment, that's sort of what it's like. There weren't discernible clouds, but the skies were obscured, with a mixture of light, haze, and various hues in the blue-gray-purple spectrum. It was weird. The sun was setting, but you couldn't really tell where it was.
I remember watching Alfred Hitchcock's The Birds when I was a kid. As I drove slowly home, dust mask in place, with the eerie skies overhead and other drivers nervously looking skyward, I couldn't help but think back to that movie. Something evil lurked in the sky. That movie creeped me out as a kid. Creeps me out to think of it now. All I needed was some really creepy mood music.
At any rate...the sky may not be falling, but the ash is.
Friday, March 27, 2009
Volcanic Activity ~ Alaska ~ March 209
2009-03-27 08:59:59
An eruption of Redoubt volcano occurred at approximately 08:40 AKDT (16:40 UTC). National Weather Service reports the cloud height to be approximately 50,000 ft above sea level based on radar.
Image above courtesy Alaska Volcano Observatory
Image below...
AVHRR (Advanced Very High Resolution Radiometer) false-color satellite image showing the eruption cloud from an explosion at Redoubt Volcano at 3:31am AKDT on March 23rd 2009. Image was captured at 5:30am and shows the ash cloud passing over other volcanoes and heading NE towards Anchorage.
Picture Date: March 23, 2009 14:30:29 UTC
Image Creator: Bailey, John; Image courtesy of the AVO/UAF-GI.
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