Detailed

Weapon Effects v2.1 (21 December 1984) by Horizons Technology under contract to the Defense Nuclear Agency
LA8819 The yields of the Hiroshima and Nagasaki nuclear explosions. Malik, J. S.
Little Boy Unit L11 initiated at a height of 580 meters above the ground with a yield of 15 kilotons. Visibility at the time was 9,855 meters. Figure used in calculations was 10 km as that was the lower bound of the validated model limits in Weapon Effects.
1.5 PSI: 3,374 meters
2.5 PSI: 2,432 meters
3 PSI: 2,169 meters
5 PSI: 1576 meters
10 PSI: 988 meters
15 PSI: 552 meters
20 PSI 359 meters
25 PSI: 204 meters
28 PSI: 80 meters <Roughly the highest pressure obtained.
3 cal/cm^{2}: 3,100 meters
5 cal/cm^{2}: 2,500 meters ← Flash burns on wooden telephone poles.
8 cal/cm^{2}: 2,000 meters
8.5cal/cm^{2}: 1,920 meters ← Flash burned shadow of valve onto adjacent painted surface. (PHOTO)
14 cal/cm^{2}: 1,500 meters
25 cal/cm^{2}: 1,100 meters
34 cal/cm^{2}: 870 meters ← Lightondark shadows of railings on pavement at Yorozuyo Bridge, 880~m from hypocenter. (PHOTO)
50 cal/cm^{2}: 650 meters
97 cal/cm^{2}: 250 meters ← Human Shadow impressions on the steps of Sumito Bank, some 250~m from hypocenter. (PHOTO)
100 cal/cm^{2}: 225 meters
115 cal/cm^{2}: 36 meters ← Roughly the highest fluence obtained.
Measured as Total Dose (tissue)
100 rad (tis): 1,524 meters
250 rad (tis): 1,343 meters
500 rad (tis):: 1,212 meters
1000 rad(tis): 1,086 meters
5000 rad(tis): 805 meters
10,000 rad(tis): 684 meters
20,000 rad(tis): 561 meters
50,000 rad(tis): 381 meters
100,000 rad(tis): 197 meters
Fat Man Unit F31 initiated at a height of 469 meters above the ground with a yield of 21 kilotons.
1.5 PSI: 3,505 meters
2.5 PSI: 2,505 meters
3 PSI: 2,225 meters
5 PSI: 1,613 meters
10 PSI: 1,051 meters
15 PSI: 817 meters
20 PSI 682 meters
25 PSI: 592 meters
30 PSI: 516 meters
40 PSI: 293 meters
50 PSI: 200 meters
60 PSI: 101 meters
NOTE: Not calculated as I was unable to find a visibility for that day at Nagasaki.
Measured as Total Dose (tissue)
100 rad (tis): 1517
250 rad (tis): 1327
500 rad (tis):: 1190
1000 rad(tis): 1059
5000 rad(tis): 775
10,000 rad(tis): 657
20,000 rad(tis): 540
50,000 rad(tis): 377
100,000 rad(tis): 227m