Re: satellite photo showing nightfall

[Mike Smith <mike@COMET.UCAR.EDU>]

A meteorologist friend specializing in satellite imagery here at work
commented:

"They're composites generated by the company Living Earth Inc..  If you want
to generate your own, you can go to a neat Website that displays the same
day/night composite with controls for zooming in on different parts of the
globe.  And the composite is updated in real-time (that is the terminator is
updated)...watch the terminator as it moves east to west!
http://www.fourmilab.ch/cgi-bin/uncgi/Earth/action?opt=-p

"For inquiring minds, the image is a composite of essentially three separate
image products.  One is the infamous DMSP nighttime lights composite, formed
by compositing hundreds of individual cloud cleared orbits between October
1994 and March 1995 (there's a cool poster widely available).  Another is a
daytime cloud cleared image, itself a composite of many cloud cleared orbits
of normalized vegetation index from NOAA-AVHRR.  And the cool underlying
ocean topography pic is based on bathymetry data."

Cheers,

========================================
Mike Smith
Cooperative Program for Operational Meteorology, Education and Training
(COMET)
University Corporation for Atmospheric Research (UCAR)
Box 3000
Boulder CO 80307-3000
e-mail: mike@comet.ucar.edu
phone: 303/497-8346
fax: 303/497-8491
========================================



----- Original Message -----
From: "Stephen Murray" <murray8@LLNL.GOV>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, January 28, 2003 5:39 PM
Subject: Re: satellite photo showing nightfall


> I believe that it's an artificially-generated image, not an enhanced
> satellite image (though generated from satellite data).  There is
> absolutely no cloud cover anywhere, which I suppose is not
> impossible, but seems highly unlikely.  Features on the ocean floor,
> such as the mid-Atlantic ridge, are visible.  That would not be
> possible in an optical image.  I don't know what kind of dynamic
> range most satellite images possess, but generally city lights and
> gas flares in the Sahara would require a much deeper exposure than
> regions in daylight.
>
> > Please have a look at this photo of nightfall over central Europe
> > that was sent to a friend of mine by a former student who is now in
> > Navy satellite imagery.  Can anyone tell me if this is a single image
> > or one that was pieced together using a number of images and then
> > visually enhanced?
> >
> > http://www.siu.edu/~cafs/download/Sunset.jpg
>
>
> ================================
> Stephen D. Murray
> Physicist, A Division
> Lawrence Livermore National Laboratory
> Email:  sdmurray@llnl.gov
> Phone: (925) 423-9382
> FAX:    (925) 423-0925
> ================================