Dust Storm |
Dust Storm |
Oct 18 2005, 05:47 PM
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#1
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Junior Member Group: Members Posts: 71 Joined: 11-May 05 From: Colorado USA Member No.: 386 |
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Oct 31 2005, 03:30 PM
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#2
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Senior Member Group: Members Posts: 3009 Joined: 30-October 04 Member No.: 105 |
This didn't quite show what I'd hoped it would, but here it is for your FWIW file...
Here is a montage of four Forward Hazcam images from Sols 627, 626, 624 and 616 that semi-shows a build-up of dust in the atmosphere, but not conclusively. --Bill -------------------- |
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Oct 31 2005, 03:44 PM
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#3
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Member Group: Members Posts: 147 Joined: 30-June 05 From: Bristol, UK Member No.: 423 |
The latest hazcam pictures show the shadow as being sharp - as I would expect.
BUT the shadowed zone is lighter indicating that there is more "ambient" light. Think of the sky here on earth and compare the shadows on a cloudless day: 1) in a smoggy city (say LA) 2) in mountains. Both have crisp edges but the contrast in the mountains is much higher. The latest rear hazcam images definately show a reduced shadow contrast. Nick |
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Oct 31 2005, 03:46 PM
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#4
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Interplanetary Dumpster Diver Group: Admin Posts: 4405 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
I imaging the stretching of the "raws" wrecks havoc on our ability to determine how much the brightness of the seen is effected.
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Oct 31 2005, 04:32 PM
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#5
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
QUOTE (tedstryk @ Oct 31 2005, 04:46 PM) I imaging the stretching of the "raws" wrecks havoc on our ability to determine how much the brightness of the seen is effected. True but there are a couple of things to note that can give us something to work on. Tau=5. There will be no clear shadows at all, at noon the diffuse illumination will be about 2 orders of magnitude more intense than direct beam illumination and it's even more extreme when the solar elevation is low. Tau=2, There will be faint shadows, diffuse lighting at midday is about 5x the intensity of the direct beam, and once again that rises significantly further from noon. Tau=1, Clear shadows are visible but shaded areas are well illuminated. Diffuse light is about 20% higher than direct at noon. Overall daily diffuse insolation is about 80% more than direct beam. Tau=0.5, Crisp shadows and shaded areas are noticably dark. Direct beam is ~70% more than diffuse light at noon. Total daily beam insolation is abotu 20% more than direct beam. Tau=0.1, Extremely well defined shadows. Beam lighting is ~10x the intensity of diffuse at noon. Things get a bit fuzzy very early\late in the day when tau is above ~0.2 as direct beam falls off rapidly at low sun angles while diffuse light falls off pretty slowly. |
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