Fireball of Castle Bravo, the largest nuclear device ever detonated by the United States of America. The picture was taken from about 40,000 feet, Bikini Atoll; ca. 1954

The photo was taken from a plane flying 75 nautical miles from ground zero, from an altitude of 12,500 feet. The fireball is over 4 miles wide.
A Japanese fishing boat, Daigo Fukuryu Maru, came in direct contact with the fallout. The fallout, fine white flaky dust of calcinated Bikini Island coral, had absorbed highly radioactive fission products, and fell on the ship for three hours. The fishermen scooped it into bags with their bare hands. The dust stuck to surfaces, bodies and hair; after the radiation sickness symptoms appeared, the fishermen called it shi no hai (死の灰?, death ash). The crew members, suffering from nausea, headaches, burns, pain in the eyes, bleeding from the gums, and other symptoms, were diagnosed with acute radiation syndrome and admitted to two Tokyo hospitals. Seven months after the test on September 23, chief radio operator Mr. Aikichi Kuboyama, 40, died — the first Japanese victim of a hydrogen bomb. He left these words: “I pray that I am the last victim of an atomic or hydrogen bomb.”
This resulted in an international uproar and reignited Japanese concerns about radiation, especially in regard that Japanese citizens were once more adversely affected by U.S. nuclear weapons.
The Japanese and U.S. governments quickly reached a political settlement and paid out US$2 million to the surviving victims, each receiving about ¥ 2 million each ($5,550 in 1954, $47,400 in 2013). It was also agreed that the victims would not be given Hibakusha status.
B-57B observing a nuclear test during Operation Redwing, Bikini Atoll; ca. July 12th 1958
Here is a video of the shot. It was the fifth largest nuclear shot by the US ever, at 9.3 megatons. It really does look like a sunrise/set (only at 1000x speed).
(I recently read Command and Control, would recommend it, covers a lot of the insanity regarding nuclear weapons. Apparently, up until the 80’s they were surprisingly easy to to set off, none of the PAL stuff you see in movies these days. Right after World War Twi they were still trying to figure out how to work nuclear war into scenario planning, it leads to a lot of crazy phrases like “limited nuclear war” or “progressive escalation” in terms of how to use the weapons not just against the soviets but also against weaker world powers. I think the USA did get a bit of a God complex for a bit, but once the cold war started it balanced it out to a more muted insanity and paranoia as they realized that just about any major power could drop a nuke and it might just set off the rest of the world, intentional or not…)
Crossroads Baker nuclear explosion of July 25, 1946, test fired at 27m underwater. Photo taken from a tower on Bikini Island, 3.5 mi (5.6 km) away.

There is controversy over the black splotch in the lower right corner of the blast whether it is the battleship Arkansas (which weighed 26,000 tons and was 562 feet long) or if its smoke from the detonation.
This is a picture from the 1946 detonation of a 23 kiloton nuclear bomb (same device design that was used to bomb Nagasaki) during operation Crossroads in Bikini Atoll in the Pacific. This tests was designated Baker denoting that it was the second in the series of 3 planned tests (but only two were carried out. The first being Able). It was the 3rd nuclear test ever conducted, and the 5th nuclear explosion in history.
The bomb was detonated 90 feet underwater amidst a fleet of decommissioned US and seized Japanese vessels. It was meant to simulate and document the effects of nuclear weapons in naval warfare.