Join Date: Feb 2000
Location: Annapolis, Md
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Re: ambient wind vs true wind
'Ambient Wind', 'Gust', and 'Apparent Wind' are three separate terms. Ambient wind and gusts are both true winds in that they are measured from a stationary position. They are solely meteorological. Ambient wind is the average steady wind measured at a stationary point such as a weather station like Thomas Point. As NOAA defines the term 'Ambient', it means, "Of the surrounding area or environment." Gusts are a sudden and short lived increase in wind speed above the ambient wind speed. NOAA defines gust as "A rapid fluctuation of wind speed with variations of 10 knots or more between peaks and lulls." but we all know it as that sudden increase in wind.
If this was a college entrance exam, 'Apparent wind' would the one term which one does not match the other two of the three. Apparent wind is the wind measured from a moving object, such as a boat under way. It is the wind that results from combining the velocity (speed and direction) of the true wind with the boat's velocity relative to that true wind velocity.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay