Marine Glossary

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quadrant

1. A 90° sector usually specified relative to a specific bearing or orientation. The northwest quadrant covers bearings or winds from west to north. A storm sector referred to as "within a radius of 300 miles in the east quadrant" would refer to that pie-shaped sector from the northeast to the southeast, extending out 300 miles from the center of the Low.

A semicircle is two adjacent quadrants. The "SE semicircle" implies the region spanning bearings of 045 to 225 centered about the location of the Low.

Samples of this use of these terms are presented under weather report.

2. Several meteorologists, and notably David Houghton in his several publications, who analyze sea breeze development, classify the pre-sea-breeze wind according to specially defined "quadrants" of the prevailing gradient wind. Facing the shore, offshore wind from the left is called quadrant 1, from the right is quadrant 2. Onshore flow from the left is quadrant 3, and front the right, quadrant 4. This classification leads to useful means of predicting sea breeze development, as discussed in ART-4 on sea breezes.

3. For completeness, we mention that quadrant is also used to describe an instrument used to measure the angular heights of celestial bodies, as described in the author's book Emergency Navigation. Analogous instruments are the octant and sextant.