We want to communicate with eachother, which is what language is all about.
To do that effectively, we refer to it as steam because it is steam, it is accepted common usage, and various dictionaries include the popuar usage.
I’m just curious. On googling “Alumni Hall” and “New York City”, I find that it’s a sort of stadium or arena, but when I read your OP I thought it was some sort of residential hotel or apartment house. Or is Alumni Hall also the name of a university dorm in the neighborhood?
Can you explain this, if you don’t mind?
I just want to point out that the steam billowing from manholes produces an interesting side effect: orange and white-striped street chimneys!