all images and text copyright © 2001 Mark Smith : not for commercial use

Notes:

These pictures were taken with a Nikon Coolpix 990 digital camera at a resolution of 1024x768.
Some have been passed through a sharpness filter, and a couple have had the brightness increased.
Image 20 was cropped and rotated to more-or-less match image 1. No other changes were made.

Some people have remarked on the lack of smoke in image 20. I'm not sure why it isn't visible.
The roofline across the street corresponds to a height of a few hundred feet in lower Manhattan;
my best guess is that the wind was carrying the smoke northwest and it didn't reach that height
until outside the frame of the picture on the right.

My thanks to the many people who have shared their thoughts after viewing these pictures.