There are two images in this sequence. These match frames 1 and 3 of the six frame shot. They are taken from the opposite direction of where the six frame shot was taken.
Both photos are centered on the second tower. Behind and to the left the first tower may be seen belching thick black smoke. The smoke is being blown towards the camera, over the second tower, and to the right of the frame. Where it first leaves the building it is very dense and dark, but once it has passed over the second tower the underside of the cloud is thin and light in colour. The second tower is causing some air turbulance which can be seen in the bulges of the grey cloud.
In the bottom right of the frame is a tall brown building. It is close to where the photographer is standing. The photographer is perhaps 800 metres from the Twin Towers, or is using a telephoto lense.
In this first image the airplane is seconds from crashing into the second tower. The plane is dwarved by the building. Although on an angle, its width is only 60 percent of the width of the building.
The plane, which is flying away from the photographer, towards the tower, is on an angle. The wings point out the times of 7 past 8 on an analogue clock.
Two bright orange balls of flames are visible in this picture. One is on the face fo the tower closest to the photographer covering where the plane first entered the structure. This is the smaller of the fireballs. From it a cloud of debris and rubble is falling, appearing like a straggly facial hair from a giant puffy orange chin.
The other fireball, here seen side on, is similiar although much larger. It reaches nearly to the top of the building, some thirty stories perhaps from where the plane crashed. The fireball is yellow with orange detail surrounding the flames. At the extremeties gray smoke can be seen. At the base of the ball is a small black cloud poking out like an afterthought.
Again the goatee of debris flied down into the street below. It is being scattered as far from the building as the width of the building itself. The debris appears like a rain of confetti: uncountable small but discrete items falling downwards out of a white cloud.
Source: unknown