Apple TV has three top-tier shows all airing right now, but the streamer is assembling a strong summer lineup too, anchored by the return of two of its all-time biggest hit series. #1: Silo, the dystopian sci-fi hit, is back this July Silo is one of Apple TV’s most popular sci-fi series. It may not have achieved Severance or Pluribus levels of reach, but its second season became one of the only Apple shows to ever hit the Nielsen top 10 chart. Almost exactly 18 months after its last episode aired, Silo returns this summer for a new season. Silo season 3 arrives Friday, July 3  with its premiere episode, then weekly releases through September 4. The dystopian series is based on  the book trilogy  by Hugh Howey. Apple has already confirmed that season 4 is coming too, and will conclude the story.…