On December 19, 1968, U.S. Patent No. 3,415,512 issued on Apparatus Causing Artificial Snowfall:

The principal object of the invention is “to provide apparatus that assures a continuous movement of snow particles, repeatedly blowing them upwardly to a point where they are dispersed and will fall downwardly and thence return to a predetermined point without manual or mechanical assistance, for an indefinite period of time.”

Somewhat surprisingly, there is some prior art: U.S. Patent No. 3,147,175 issued September 1. 1964:

Inventors continued to refine the technology into the 1970’s, see U.S. Patent No. 4,028,830:

However, it was not until 1975 when someone thought to enclose the whole system, as shown in U.S. Patent No. 3,905,140.

U.S. Patent No. 4076234 continued the development of this important decorating technology:

Interest in turning the living room into a snowglobe continued into the ’90’s, as evidenced by U.S. Patent No. 4,962,922

and U.S. Patent No. 5,098,084: