H-HOUR AT ELUGELAB

THE cloud itself was kind of rough," wrote a sailor, "yet it looked smooth -- something like a cauliflower." Poets were not invited to Operation Ivy to witness the dawn of the hydrogen age, so it was as a cauliflower that the H-bomb's first cloud was trademarked last week -- a realistic if nonpoetic progression in vegetables from the A-bomb's first mushroom.

Ivy's explosion broke the stillness of a mid-Pacific morning on Nov. 1, 1952; at 7:15 a.m., observers on ships and planes 50 miles away watched an enormous deep-orange fireball blaze up in the distance. Then it rose to the stratosphere, trailed by a churning grey-brown pillar of water and the pulverized remains of the little sandspit of Elugelab. As the cloud cooled, it began to billow outward.

Its colors lost their infernal intensity, paled to harmless-looking but deadly pastels. Then, slowly the 100-mile-wide cauliflower drifted away and disappeared.

For more than a year, the public heard only rumors and skimpy statistics about Operation Ivy, the first full-dress thermonuclear explosion. Then, last winter, the U.S. Government decided to release the full story. President Eisen hower, speaking of atomic development, told the United Nations that "the peoples of the world . . . must be armed with the significant facts of today's existence." The shapes and colors of Operation Ivy are part of the story which the Government is gradually releasing. Three weeks ago, the press published some Statistics about the blast, along with black and white photographs. Some still Cuts from color motion pictures followed. On the next four pages, TIME publishes the first color pictures taken with a still camera of the explosion at Elugelab.

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