  A simple method to get all main characteristics of nucleation process is
proposed. The advantage of this method is an applicability to situations with
non-linear behavior in time of effective external source of vapor. It is
important because already existed objects of a new phase comsume vapor in
non-linear manner and form an effective non-linear behavior of external
conditions. To describe kinetics in this situatrion one can use a method
proposed here. As the result some exact expressions for all main
characteristics of nucleation kinetics are obtained.
