I'm looking for a word that means to circle outward from a center point, with each circle getting a little larger than the previous, as would be used by a search party, for example.
"The helicopter flew in ______ circles as we peered down toward the trees."
"Start there, and [walk (or any motion) in] ______ [circles] until you find a table with your name on it."
A single word for the whole thing would also be acceptable.
I found this word "circumnutation," but the main meaning of that word seems specific to plants, and the directly relevant version of the word is marked as not accepted and might not be standard. It's also specifically referring to ripples in water, which is not what I'm looking for. I also think the word I'm looking for is something I've encountered in the past, just can't remember at the moment.