With temperatures below freezing and saturated air (high relative humidity) aircraft descending to land can cause snow. It’s a very localized event, not widespread snow, but snow can form and then fall as a result of planes descending under the right conditions.
This requires “supercooled atmosphere interacting with exhaust” and “water vapor [that is] below freezing but [that] couldn’t entirely transition into ice crystals because of a lack of particulates upon which to freeze.” Then the plane descending through the atmosphere causes snow to form.