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Wind and Turf

See also Pumping Capacity Calculator
and Straight answers on watering

  Hourly variation in wind speed in Davie, Florida
  Wind speed is often a predictable factor in turfgrass culture.  Values were measured 2 feet above the ground and averaged across dates, at U of F - Fort Lauderdale, located in Davie, Broward County, Florida.
  

Turfgrass maintenance activities are frequently confounded by the elements of weather.  As one example, spraying of pesticides such as herbicides can be messed up by the wind.  Spray drift by wind can damage neighboring desirable plants, or can even damage the turf, as the weed killing chemical is blown into concentrated areas on the lawn or golf course.  But if the homeowner or the golf course superintendent knows when to expect the wind, it's a lot easier to schedule spraying when there is reduced chance of wind drift.

To see up-to-the-last-15-minutes wind speed at many stations in Florida, you can visit:
       http://fawn.ifas.ufl.edu

Most people realize that the early hours of the morning are comparatively free of wind, and afternoons are breeziest.  This graph shows how extreme and how predictable the effect is in South Florida.  The same pattern would not be so consistent for other areas even within Florida, for example areas in northern Florida such as Gainesville are influenced by different prevailing wind patterns.

Normally, the applicator should spray pesticides when the wind is less than 5 miles per hour, depending on the spray droplet size and the elevation of the spray nozzles above the ground.

In the example from the FAWN automatic weather station University of Florida Fort Lauderdale Research and Education Center, during predawn hours, before about 0700 hours in the morning, wind averaged less than 4 miles per hour.  But after 0800 hours the graph shows that wind averaged more than 5 miles per hour.  (I was able to begin developing the graph by selecting just the cells from the FAWN weather chart, and copying and pasting them into an Excel spreadsheet.  But FAWN will also make some nice graphs for you.)

On any given day, higher or lower wind speeds were encountered, but knowing the average wind speed for a time of year is a good place to start for planning maintenance activities.  Wind, at least, is more predictable than rain.  The corrupting influence of wind can severely affect uniformity of irrigation, and is a major factor in determining the water used by plants, that is, evapotranspiration.  See also:
         http://c-11.org/landscape/wind.html

Reported wind speed is only relative, because it is much windier high above the ground.  Small droplets sprayed a few feet above the ground can drift entirely away from the intended target, even in a 5-mile-per-hour wind.  Large droplets sprayed less than a foot above the ground can sometimes be sprayed under conditions of stronger wind.

Fortunately, in some areas of the world, certain expressions of weather are predictable.  For example, in the parts of the globe influenced by the trade winds, such as South Florida, wind is a largely daytime event.  Although the main regional circulation pattern is from the northeast, it is influenced by local factors to make it from the east or east-by-southeast.

In 1686, four years after he saw the famous comet that bears his name, British astronomer Sir Edmund Halley explained the trade wind and other large-scale wind movements by differences in terrestrial heating.

 

Turfgrass.com is a community service of:

Phil Busey Agronomy Consulting Inc.
www.philbusey.com

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