Wednesday, April 27, 2011
You may have already heard the low, insistent hum treading stealthily into your early morning dreams. Perhaps you know from whence it comes - or perhaps, like so many non-farming residents, you are still wondering.
No, it's not the arrival of extraterrestrial invaders.
The sound you are beginning to hear, which is following the footsteps of a tricky Valley visitor, is the thrum of orchard fans working like foot patrolmen combating a silent killer - otherwise known as Jack Frost.
With more than 14,000 acres of tree fruit in the Valley and emergent buds in development, frost is one of the biggest threats orchardists are facing at this time of year.
"There are eight or nine different stages of fruit bud development," said Steve Castagnoli, OSU Extension horitculture agent for Hood River County. "Different fruit buds are affected by critical temperatures at different points."
Here's the bottom line: When frost forms on a bud, it can, to put it bluntly, kill it dead - leaving devastated crop harvests for the summer and fall, fewer fruits for our tables and significant local economic impacts.
Somehow that familiar hum now begins to take on a more complex tone, perhaps appealing to more ears than farmers' alone.
Frost fans work in a very effective manner - particularly on nights with clear skies, calm wind, freezing ground temperatures and warmer above-ground air. These conditions are known as radiation frosts with cold inversion.
Fans are turned on as orchardists receive alerts from the daily frost report - provided by a Seattle-based meteorologist whose services are contracted for by Columbia Gorge Fruit Growers.
When engaged, the fans push warmer air toward the ground, creating a mixture of warmer and freezing temperature air and preventing the formation of frost.
When there is no inversion (warm air above freezing air) orchardists must resort to the use of orchard heaters to interfere with frost formation.
According to Jean Godfrey, executive director of Columbia Gorge Fruit Growers, some of the first frost fans went on this year in Odell and the upper Valley on Monday, April 18. More fan nights are expected this week as well.
The length of run time for the fans depends entirely on weather conditions and the location of the orchard, with various micro-climates spread across the varying geography of the valley.
"Last year, we had to start fans a couple of times as early as midnight," said Godfrey, referring to a few treacherous nights during last year's growing season.
Fans will run until temperatures and conditions change enough to ensure a frost danger has passed.
"Most growers have alarms in their homes which go off when temperatures reach one degree above the danger zone," said Godfrey. "That's when they get to work protecting the buds."
On average, one fan can effectively serve between 8 and 10 acres of trees, according to Castagnoli, who estimates that about two-thirds of area orchardists use fans.
"There are areas on the East Side slopes and around Oak Grove that are without fans," noted Castagnoli.
Orchard heaters add a secondary line of defense against frost for orchardists. Newer models typically use propane fuel to burn for heat. Older versions still rely on diesel. Both models heat the air within the orchard, providing that critical frost-preventing mixture of warmth and cold.
"It is pretty uncommon here," said Castagnoli, "but there are also some farmers who use sprinklers to manage frost as well."
Any form of sprinkling (under tree or over tree) will work to prevent frost formation by utilizing the thermal energy (heat) of the water in combating lower air temperatures.
Unfrozen water, by definition, exists at a temperature above freezing. Think of sprinkler use on orchard soil or tree branches as a little like letting the water run through your pipes to prevent a freeze-up.
To simplify the concepts: Temperatures on buds will be prevented from dropping below 32 degrees while 33 degree or higher temperature water is warming colder air temperatures or while water is present and undergoing the process of turning into ice.
For the geeks out there, this second phenomenon is described under the scientific phrase known as the latent heat of freezing - wherein a small amount of heat is released as the water transitions between its liquid and solid states.
Orchardists use these phenomena by continually applying water in a sprinkling method to maintain above-freezing temperatures until conditions improve.
The science may be complex, but the application of the science is executed in simple hard work.
Skilled, vigilant farmers prepare for the battles in every season, understand their land and trees, learn their science and apply the interventions and manpower needed to bring in a successful harvest.
Tonight, your neighbor may be out there in the wee hours ready to ignite heaters or switch on the fans in time to beat the next dangerous single-digit drop of the mercury.
Most of the rest of us are lucky enough to lie in bed simply wondering where the humming comes from.
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Parkdale third graders sing "12 Disaster Days of Christmas"
Welcome to your sing-able Christmas gift list. What follows is an emergency rendition of “12 Days of Christmas” – for outfitting your home or car in case of snow storm, earthquake, flood or other emergency. Read it as a simple list, or sing it to the tune of “12 Days” – you know, as in “ … and a partridge in a pear tree…” Not to make light of it, but the song is a familiar framework for a set of gift ideas that you could consider gathering together, even if the recipient already owns items such as a bunch of coats, tire chains and flashlights. Stores throughout the Gorge are stocked up on all these items. Buying all 12 days might be prohibitive, but here are three ideas for checking any of the dozen off your list (notations follow, 1-12.) The gift items needed to stay warm, dry and safe are also coded to suggest items in your abode (A) in your car (C) or both (B). 12 Gallons of Water (A) 11 Family meals (B) 10 Cans of propane (A) 9 Hygiene bags (B) 8 Packs of batteries (A) 7 Spare coats (B) 6 Bright red flares (C) 5 Cozy blankets (B) 4 Tire chains (C) 3 Flashlights (B) 2 cell phone chargers (B) 1 And a crush-proof first aid kit (B) Price ranges? Here’s a few quotes for days Three, Two, Four and Nine: n A family gift of flashlights (three will run $15-30, Hood River Supply, Tum-A-Lum) n Cell phone chargers (two will run $30-60) n Tire chains (basic set, $30, Les Schwab, returnable if unused for the winter) n Family meals ($100 or so should cover the basics for three or four reasonably well-fed days) n The home kit should be kept in a handy place near an exit, and remember that water needs to be replenished every few months. If you have a solid first aid kit already, switch out the gift idea with “and-a-sto-o-u-t- tub-for it-all …” Otherwise, it’s a case of assembling your home or car kits and making sure all members of the family know what the resources are and how to use them (ie flares and propane). Emergency situations are at worst life-threatening, at best deeply uncomfortable if you and your family are left without power for an extended period, or traveling and find yourself in a situation where you need to wait out a storm, lengthy traffic delay, or other crisis. Notes on the 12 gift ideas: 12 – Gallons of water: that’s one per person in a four-member family to last for three days, the recommended minimum to be prepared for utility outages. 11 – Easy-open packaged goods, energy bars, dried food and nuts are good things to include for nutrition. Think of what your family of four needs for three days to stay fortified and hydrated (see number 12). Can-opener also recommended 10 – If you have a propane camping stove, keep extra fuel handy. 9 – Hygiene bags: put packaged moistened towelettes, toilet paper, and plastic ties in large garbage bags (for personal sanitation) Resource list courtesy of Hood River County Emergency Management, Barbara Ayers, manager/ 541-386-1213. The county also reminds residents to Get a Kit, Make A Plan to connect your family if separated, and Stay Informed. See www.co.hood-river.or.us to opt-in for citizen alerts. Enlarge