Word of the Day
11 July 2026
vertical deflection
nounSurveying
A measure of how far the direction of the local gravity field has been shifted at a certain point on the Earth by local anomalies such as nearby mountains.
Why this one
Every instrument you level is trusting a plumb line, and a plumb line points at nearby mass as well as the Earth's centre. Big terrain pulls the local vertical off the ellipsoid normal, which is why geodetic work separates observed astronomic positions from computed ones.
In use
We are working right under the range here, so the astro fix will not tie to the grid until the vertical deflection is taken out.
Written by our editors to show how the term is used, not a recorded quotation.Sources
- Definition sourceWiktionary