The slow, deformation and densification of snow under the influence of gravity. Not to be confused with collasping
Settlement and Sintering:
A newborn, snowflake that falls out of the sky doesn't stay that way for long. As soon as it lands on the snow surface it begins a rapid process of change. Just like people, as a snowflake ages, its beautiful, angular shape becomes progressively more rounded through time and it forms bonds with its neighbors. In people, it's called growing up; in the snowpack it's called "sintering"--forming bonds with neighboring crystals to create the fabric of the snowpack.
As sintering progresses, the snow becomes denser and stronger, which we call "settlement." Sometimes you will hear people incorrectly use the term settlement to describe the catastrophic collapse of a snowpack that often makes a giant "whoomph" sound, as in, "Hey, did you hear that settlement? Maybe we should get out of here." Instead, we call these collapses or "whoomphing", which, believe it or not, is actually the technical term for a collapsing snowpack. It sounds funny but it's a great description. Settlement is the SLOW deformation of the snow as it densifies and sags under the influence of gravity.
New, fluffy snow settles relatively quickly, within minutes to hours and it settles much more quickly at warm temperatures than in cold temperatures. We often think of settlement within the new snow as a sign of stability (at least within the new snow) because it means that the new snow is rapidly becoming stronger. When new snow settles, it forms "settlement cones" around trees and bushes where the snow bonds to the bush which props up the snow, like a circus tent.