Bulldog wrote:Here's how it works:
There are three ways to raise the temperature in an agricultural setting: Burning stuff, which the AQMD frowns upon; Generating wind with a big wind machine, which keeps the air moving (and is really expensive and doesn't work if there's a wind chill); and irrigating the field.
Temperatures below 26 degrees destroy citrus fruit. Temperatures below 22 degrees for more than an hour or two can defoliate or even kill the tree entirely.
If you run enough water on the ground or through the air, it raises the air temperature. We were watering the field in that picture with overhead sprinklers, about 1000 gallons a minute over the 2 acres of trees. The water from our well is 65 degrees, which is much warmer than the 18 degrees the air was last night. As long as you keep the water moving, it keeps the temperature up.
Ice forms at 32 degrees (duh) and stays at 32 degrees, which is also warmer than 18. So the ice on the leaves insulates the plant from the colder air. Unfortunately, in this case we had to run the water for so long (12 hours on Saturday night) that the giant icicles ended up snapping many of the branches on the trees. Still, broken branches are better than dead trees.
Unfortunately, last night the pump running the sprinklers stopped working for several hours and I didn't get it running until after midnight, so the trees suffered a certain amount of freeze damage in the interim. They aren't dead, but they'll probably lose most of their leaves and get set back a year or so in their growth.
Does that answer most of your questions?
The ice will absorbe the heat of the new water to keep it at 31 degrees. If there is not a countinuous supply of water then the ice will continue to get colder. With grapes 30 degrees on green growth will ruin the crop (lucky they go dormant (sp?) during most of the cold season. The fans blow the inversion layer of air (20 to 40 feet high the air is warmer) to the ground.
I never get the opportunity to talk about it now that I don't work for a winery.
I'm such a blow hard.....
BTW- Paul come spring I need to hook-up with you and work out a veggie deal.
Kiters working with kiters I found is the way to go! You'll be able to afford new kites and I'll pick up your kites!!!