What is "accumulations"

Usage examples of "accumulations".

I think, explain this as readily as the slow and gradual accumulations of instincts which had never passed through the intelligent and self-conscious stage, but had always prompted action without any idea of a why or a wherefore on the part of the creature itself.

The idea is that a slight warming would enhance evaporation rates and increase cloud cover, leading in the higher latitudes to more persistent accumulations of snow.