STILL UP IN THE AIR ABOUT THE TITLE.
The world starts to experience a strange new natural disaster where all of the sudden an entire cloud can instantly freeze and fall from the sky as one huge ice chunk, sometimes the size of whole cities, these occurences are totally random and have the potential to kill millions of people at a time if they land on the right spot.
This idea would be a look at how humanity begins to deal with this new threat.
(by the way, I came up with this idea long before I ever saw the movie "Interstellar")