Smithsonian Magazine has an interesting theory by historian Tim Maltin to explain the Titanic disaster’s mysteries including why it didn’t see an iceberg (yes it was dark, but still), and why the Californian didn’t see it.
Atmospheric conditions in the area that night were ripe for super refraction, Maltin found. This extraordinary bending of light causes miraging, which, he discovered, was recorded by several ships in the area. He says it also prevented the Titanic’s lookouts from seeing the iceberg in time and the freighter Californian from identifying the ocean liner and communicating with it. A 1992 British government investigation suggested that super refraction may have played a role in the disaster, but that possibility went unexplored until Maltin mined weather records, survivors’ testimony and long-forgotten ships’ logs.
Essentially they think thermal inversion may be the culprit.