That would vary from place to place, and from day to day. You can see the times of sunrise and sunset for an entire year on the U.S. Naval Observatory's Astronomical Data web page at the link below.
http://aa.usno.navy.mil/data/docs/RS_OneYear.php
Water-Skiing
All around white light must be displayed between sunset and sunrise.
At the north pole, there was no sunrise on that date. At the south pole, there was no sunset. Anywhere in between, the times of sunrise and sunset depended on the latitude of the location.
Night is the period of time between sunset and sunrise.
"daylight" (hours)
That it's dark and that it occurs between sunset and sunrise.
The hours between sunrise and sunset.
In the broadest sense, that interval is generally referred to as "night".
Sunrise to sunset. It is illegal to tow a skier or similar device between sunset and sunrise.
Sunrise = Alba, Sunset = tramonto
The period of darkness between sunset and sunrise
between sunset and sunrise