Om me ao \ 1 * eet FOREWORD a A large volume of official information has been issued concerning Nevada nuclear testing since Nevada Test Site was activated in January 1951. The information made “public has been contained in official publications and reports of the Atomic Energy Commission, the Department of Defense, the Federal Civil Defense Administration, other Federal organizations, and the joint Nevada Test Organization. Prior to the Spring 1952 series, the Test tion received many requests from newsmen, from officials, and from representatives of Federal for a compilation of officially-approved basic tion to be used as a source book. AS a result Organizapublic agencies informathe first compilation of Background Information was issued during the 1952 series. In order to meet similar requests, the information Summary has been brought up-to-date for each subsequent Nevada Series, incorporating data released officially in the interim period. . The present Background Information is such a compilation. It does not attempt to be all-inclusive. Many supplementary details are available elsewhere, for instance in the 1957 revision of "Atomic Tests in Nevada," the various semiannual reports of the AEC to Congress, and the Government publication "The Effects of Atomic Weapons." Such publications are usually available in public libraries. . -¢ All material summarized here has been officia’ly released previously, following security and classification reviewby the Federal agency with primary responsibility for the subject matter. «f= CLOUD FOLLOVING NUCLEAR DETONATION IN NEVADA