NCEES Principles and Practice of Surveying Practice Exam

What characterizes a diurnal tide?

1. One high tide and one low tide each day

2. Two high tides and two low tides each day

3. Irregular tidal heights daily

4. Variable tidal timings

The correct answer is: One high tide and one low tide each day

A diurnal tide is characterized by having one high tide and one low tide each lunar day, which is approximately 24 hours and 50 minutes. This tidal pattern is typically observed in certain coastal locations where the gravitational pull of the moon causes a distinct rise and fall of sea levels. The singular occurrence of high and low tides in a 24-hour period differentiates diurnal tides from other tidal patterns where multiple high and low tides may occur. By understanding this characteristic, it becomes clear that locations with diurnal tides experience a simpler tidal system compared to mixed or semi-diurnal tides, where the timing and heights of the tides show more complexity. The option related to irregular tidal heights and variable timings pertains to different tidal phenomena or influences but do not define diurnal tides specifically.