How did the sun look when it came out after the rain stopped?

The sun looks marvelous to the children who have never seen it before. The narrator likens it to many things. It looks like "blazing bronze" against a sky that looks to the children like a blue tile. It feels like a warm iron on their faces. They compare it to the sunlamps they have known almost all their lives and think it is much better than those. They stare up at it, amazed at its yellowness.
Bradbury tries to capture and convey how children who never remember having seen the sun experience it. They have no context so can only compare it to the things they know from the tunnels they have lived in most of their lives: they compare it to items such as irons. They seemed to be primarily amazed by its vividly bright colors, as they have lived so long in a gray universe.