[UPDATE: Some of these photos are now available again with a "personal non-commercial use" licence via Google.
The following images were all found on the Life Magazine web site. Originally they linked to the page on Life where the photo could be ordered, but Life has since re-organized the site, and many photos are no longer available. The small version of each photo is embedded directly from Life.com, and originally went to page where you could order the photo. It still works for some of the older photos (like the WWII photos with the Jeep).
1988 - A vapour trail crosses the sky above the Suleymaniye Mosque and the Yeni Cami or New Mosque in Istanbul
1970 - Vapour trails across the sky
1970 - Vapour trails across a pink sky at sunset
1956 - Trio of B-47 bombers in flight leave multiple vapor trails across the sky
1956 - A sky shot of the UN headquarters (Contrails over the Empire State Building).
1949 - Vapor trails from RAF planes in the skies over England recall the convolutions of British & German pilots fighting air duels throughout the summer of 1940 during the Battle of Britain.
1944 - Alerted GIs of M-51 Anti-aircraft Battery silhoutted against German sky streaked w. vapor trails from Allied & enemy planes engaged in Christmas Day dogfight
1944 - Allied aircraft vapor trails in skies above US soldier unloading a jeep outside (prob.) farmhouse in the Ardennes Forest during last days of the Battle of the Bulge, the final major German offensive of WWII.
1944 - Allied aircraft vapor trails in skies above (prob.) farmhouse in the Ardennes Forest during last days of the Battle of the Bulge, the final major German offensive of WWII.
1940 - 6th September 1940: Interwoven vapour trails over London during an early morning air raid in the Battle of Britain.
1940 - City workers were treated to thrill during a morning air raid when British fighter planes let out vapour trails during the morning's patrol.