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Volume 43 · number 9 April 11, 2017 · $4.25 Practical production tips for the prairie farmer www.grainews.ca
By Lisa Guenther
I
f you’re planning to spray, beware air temperature inversions on calm, cloudless days. That was the message from Andrew Thostenson during the Canola Council of Canada’s Cano LAB at Vermilion’s Lakeland College this winter. Thostenson is an exten sion pesticide specialist with North Dakota University. Avoiding pesticide damage dur ing an inversion comes down to understanding how inversions work and recognizing the environmental conditions that cause them, Thost enson explained to the gathered agronomists and farmers.
How inversions work To understand air temperature inversions, a person needs to know a little about thermodynamics. While “thermodynamics isn’t for every body, this is pretty easy,” says Thostenson. During the day, short-wave radi ation from the sun warms the earth, along with any other objects it hits. At night, those objects emit longwave, or infrared, radiation, revers ing the process. As the objects lose heat, the ground may cool the surrounding air. The warmest air will be highest, and the coldest air closest to the ground, creating an inversion. “If there’s enough moisture, fog walls will form. And if you have a fog situation that is an inversion situa tion,” says Thostenson. Fog might appear to form a layer close to the ground, but it’s not really a layer, he says. It’s just the point where the air temperature is cool enough to con dense moisture.
Crop protection
Understanding temperature inversions photo: thinkstock
Those calm, cloudless days may not be the perfect days to get out the sprayer
See temperature on Page 5
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Rethink Your Operation
Learn how the latest track technology can bring a higher level of efficiency to your farm year-round.
IN THIS ISSUE SEE PAGES 10 & 11