Ocean Tides — Sun and Moon at Right Angles When the Sun and Moon are at right angles relative to Earth, causing their tidal forces to partially cancel, the resulting tide is called:

Introduction / Context:
Tidal ranges vary systematically with the relative positions of the Earth, Moon, and Sun. Recognizing neap versus spring tides helps explain fortnightly cycles seen in tide tables and coastal navigation practice.

Given Data / Assumptions:

• Sun and Moon are at right angles as viewed from Earth (quadrature).
• We look for the named tide associated with reduced tidal range.
• Basic tidal terminology is assumed.

Concept / Approach:

At quadrature (first and third quarter lunar phases), solar and lunar tidal bulges are offset by 90°, leading to partial cancellation of their gravitational effects. This produces neap tides, characterized by smaller differences between high and low water. In contrast, at syzygy (full and new moon), forces align, producing spring tides with the greatest range. “Diurnal tide” describes a daily pattern, not magnitude; “ebb tide” is the falling phase of a tide, not a range category.

Step-by-Step Solution:

Identify geometry: 90° Sun–Earth–Moon alignment → quadrature.Associate with reduced range → neap tide.Eliminate other terms that refer to different concepts.

Verification / Alternative check:

Tide charts show lower ranges near first/third quarter and higher ranges near new/full moon, matching neap and spring designations respectively.

Why Other Options Are Wrong:

Spring tide: Occurs at alignment, not right angles.Diurnal/ebb: Describe timing or phase, not the reduced-range event at quadrature.

Common Pitfalls:

Associating “spring” with the spring season; the term comes from “springing forth,” not the time of year.

Final Answer:

neap tide