Especially apocalyptic given that they had never knew such things possible.

Later it became routine.

https://youtu.be/YtCTzbh4mNQ?t=62 (narrator saying - "the mushroom cloud reached 65km altitude" ) Our high school military preparedness classes teacher was a retired "Captain of 2nd rank" (subcolonel equivalent in USSR Navy) who had served at that "Novaja Zemlja" islands nuclear testing range. He was describing that regular nukes they would just watch from 20km. While large hydrogen bombs they were watching from like 200km, and it still was awe-fear-inspiring.

"Nuclear Tourism: When Atomic Tests Were a Tourist Attraction in Las Vegas, 1950s"

https://rarehistoricalphotos.com/atomic-tourism-las-vegas/ (cool sight https://1.bp.blogspot.com/-o6mAaNEPm8g/X212lrhyZPI/AAAAAAAD4... :)