Irregularity of the strength and direction of received radio waves of certain frequencies that is especially marked at night, owing to the reception of polarized waves reflected by the ionosphere; an instance of this.
Origin
Early 20th century.
Definition of night effect in US English:
night effect
noun
Irregularity of the strength and direction of received radio waves of certain frequencies that is especially marked at night, owing to the reception of polarized waves reflected by the ionosphere; an instance of this.