Peak Wind vs Maximum Wind – What’s the Difference?

Posted by in Weather Events | November 28, 2012

Weather data example

Portion of a typical weather data sheet.

 

Weather records commonly show two different values for the measurement of wind speeds (see photograph above).  What are the two different measurements and why are there two different values?  The two values are commonly called the “maximum speed” and the “peak wind.”

The “maximum speed” wind is defined by the National Weather Service as, “The highest wind speed in mph averaged over a 2 minute period.”  This is a measurement of the sustained wind that one feels as over an extended period of time.

The “peak wind” is defined as, “The highest wind speed observed at the station” during a given 24-hour period of time.  This is a measurement of a burst or a gust of wind that one feels over a very short period of time.  In the case of the peak wind, the very short period of time is usually three seconds.

(Bonus: A third column of wind measurements is the “average wind” which is defined as the average speed of the wind over the full 24-hour period.  These measurements are useful in determining where to place wind powered generating equipment, such as windmills.)

These winds speeds are most often measured at open fields, such as an airport, at a height of 10 meters (33 feet) above ground

The design wind speed used for building codes is commonly based on the peak wind recurring at a 50 year interval.  This 50 year wind is modified with various factors for exposure, heights other than 33 feet, surface roughness, terrain, wind gust, directionality, etc.  This statement is an oversimplification for this short article, but provides some idea of the relationship between recorded wind speeds and design wind speeds.

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