Paperclip, where are the actual files stored?

This is how I configured my attachment:

has_attached_file :image, {styles: { small: "64x64", med: "100x100", large: "200x200" },
                  :url  => "/assets/images/users/:id/:style/:basename.:extension",
                  :path => ":rails_root/public/assets/images/users/:id/:style/:basename.:extension",
                  :default_url => "users/default/:style/missing.png"}

The output seems to be correct:

<img alt="Missing" src="/assets/images/users/3/small/missing.png?1426087812">

However, when I navigate to the path in my windows explorer I cannot see any files.

I am running in development mode. Is that the cause? How can I find the actual files?