Sunrise sunset the amount of time in between and the sun's angular position before rising are all factors that determine the halachic times and "hours" of the day.

(The hour has special meaning in Jewish law. When we say that a certain mitzvah may be performed three hours into the day this doesn’t mean at three in the morning or three clock-hours after sunrise. Rather an hour in halacha means 1/12th of the day. Thus if the sun rises at 5 am and sets at 7:30 pm one sha'ah zemanit or proportional hour will be 72.5 minutes and all calculations will use that number.)