Mariah Carey Doesn't Do Rain!

Mariah Carey gets the royal treatment ... especially in the rain. But her supposed new boy toy Bryan Tanaka -- not so much.

A 3 person crew made their best attempt to keep Mimi dry Tuesday night as she arrived at the Empire State Building for a lighting ceremony. Bryan had just 1 schmoe.

But he gets to cavort with Mariah ... so that explains the smirk.