VIRTUAL HEIGHT (KM) 600--— soor— T | I. |! | MIKE (IVY) MIKE (IVY) 400r— ~ 300r— 200t—- CRITICAL FREQUENCY (MC) to. — NORMAL CRITICAL FREQUENCY (MC) ~ MIKE (IVY) NORMAL i 2 3 4. 5 ELAPSED TIME AFTER DETONATION (HRS) Fige 3.9 = F2-Layer Virtual Height and Critical Frequency at Rongerik Following Shots 1 and 2 and at Bikini Following Mike Shot (Operation IVY), Compared with Normal Values 34 SECRET 6