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.
I do not have real-time capabilities to provide sunrise and sunset times for specific dates. You can easily find this information by using online tools like timeanddate.com or specific weather apps that provide daily sunrise and sunset times.
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.
Night is the period of time between sunset and sunrise.
That it's dark and that it occurs between sunset and sunrise.
"daylight" (hours)
The hours between sunrise and sunset.
Sunrise = Alba, Sunset = tramonto
The period of darkness between sunset and sunrise
between sunset and sunrise