At Environment Canada, senior climatologist David Phillips' standard for a white Christmas calls for at least two centimeters of snow on the ground at 7 a.m. . . . In England, if a weather guy sees a snowflake, they call it a white Christmas..
a christmas day on which there is a ground covering of snow
الواصلة
a Christ·mas Day on which there I·s a ground co·ver·ing of snow