|
meteoptic-l [ät] ursa.fi
message archive
This is meteoptic-l [ät] ursa.fi message archive.
Note, your can reply the messages on this page only if your
are already subscribed the list.
» To the end of the list/message
Hi,
This was not a light pillar, which appears above the sun, or above any
bright light source, typically near or below the horizon. (One very cold
morning I saw a flashing light pillar from the turn-signal of a car beyond
the top of a hill!) Given the time of night, direction, and duration, this
does not seem possible.
Given your description, the two most likely events are, IMHO:
- A man-made bright-light source from Cloverdale, such as a searchlight
turned on and then off again. Could also be, for example, an upward-turned
floodlight intended to light a billboard or building, temporarily
badly-aimed while being replaced or repaired.
- An aurora of brief duration. The shape you describe is certainly
unusual,
but perhaps not unprecedented?
Given the exceptionally brief duration, I suspect the former. Any other
ideas?
Keith Pickering
> I was hoping some of the experienced people on this list could help me
> understand whether something I saw was a light pillar or what.
>
> I grew up around 30 degrees latitude so I've never seen an aurora. On
> Oct 29, when the CME from the Oct 28 solar event had hit earth (it had
> hit about 14 hours earlier), I hoped to see something so I travelled to
> a dark area north of San Francisco to see if I could spot anything. I
> had picked an area that had little light pollution.
>
> I was on the south side of Lake Sonoma (a large reservoir). The Milky
> Way was clear and bright and I was able to easily walk around from the
> light of the sky (no moon). My location was 38.7N, 123W at about 800'
> elevation. (I was on a hill above the lake, not at the shore).
>
> A high pressure area ("cold front" by California standards) moved in
> that day. The temperature was about 50 degrees Fahrenheit (10 C) (per
> the thermometer on my car while I drove and while parked). The wind was
> quite brisk, enough to push me around a bit. I'd estimate the wind to
> be 20-30 miles per hour. The entire time, there were no clouds
> anywhere to be seen.
>
> I was at the location from about 11:30PM to 2AM (standard time). When
> I didn't see any signs of aurora, I took advantage of the dark skies and
> was just touring the skies with a small telescope.
>
> Approximately 12:35AM, I looked up from the telescope and saw, without
> my glasses (-4 diopters), what appeared to be a spotlight shining up,
> directly below the North Star. I fumbled around to put on my glasses
> and saw the same thing. The telescope was completely inappropriate for
> this, so I went to dig out some binoculars. Unfortunately by the time I
> got the binoculars out, the light had disappeared. I could find no
> trace of it.
>
> At the time, I thought I was seeing some sort of light that was
> associated with an aurora, so I was thinking its source was above it and
> didn't associate it with the ground.
>
> I took note at the time that the light appeared to go up more or less
> from the ground to about 60% of the way to the North Star (ie, 22
> degrees). The light appeared white, but was not brilliantly white. As
> I said, my initial reaction was that it looked like a spotlight. (But
> of course there were no spotlights in use that night.) I didn't try to
> measure the width of the column of light but it was neither broad (as in
> an aurora) nor pencil-like.
>
> The air was exceptionally clear so I would discount its being, say, a
> police car's light that was shone straight up as there was little in the
> air to show its path. It also would have been at least 2 miles distant
> (to the other side of the lake). The light didn't move while I saw
> it. Unfortunately, I saw neither its start nor its end.
>
> When I got home, I tried to find a description of what I had seen. I
> quickly found references to pillars. Although I had thought of this
> beam as being below the North Star, it turned out it was also above the
> lights of a town 10 miles (16km) north. I was directly south of
> Cloverdale, a city with a population of about 5,000. Its lights were
> obvious but their glow went up less than 5 degrees. About 10 degrees to
> the west were the lights of a city of 16,000 that was 30 miles away. A
> star was visible just barely above the horizon in between the two.
>
> One description I read indicated that pillars often went to 20 degrees
> above the horizon which corresponded to what I had seen. I felt sure
> that this is what I had seen.
>
> My question about it being a pillar is that the air temperature (50F/10C
> at 800') seemed well above what I've seen for most other descriptions of
> pillars. Also, I wonder about the fact that the wind was brisk. I
> don't know if that would allow for an alignment of ice crystals that
> would allow for this to be seen for about 30 seconds to a minute. I'm
> sure at higher altitudes the air was colder but also the wind would
> likely be stronger. (The location is maybe 50 miles inland from the
> Pacific Ocean with the wind blowing from the NW.)
>
> If the pillar's light source was the town and the ice crystals were
> directly above it, the top of the pillar would be 4 miles in altitude.
> I expect though that the ice crystals would be half way between the
> light source and me, so the top would be 2 miles up. I also am pretty
> sure that the pillar went most of the way to the ground so that I'd
> expect that if this were a pillar, I would have seen reflections off ice
> crystals that were no more than a half mile (1km) in altitude. While I
> could believe it was freezing at a half-mile in altitude, I'm not sure
> that there would be the necessary conditions to get these ice crystals.
>
>
> Another possibility is that the light source for this pillar was much
> further north and that I was seeing something that was a reflection of
> that light. Then the ice crystals would be much higher in the
> atmosphere at a much colder temperature. There are no significant
> cities north of my location for about 350 miles. (But, for all I know,
> it could be reflecting an aurora that I couldn't see.)
>
>
> I was hoping that those more familiar with pillars and auroras could
> clarify what it was that I saw.
>
> Thanks!
|